I would generalise this a little: The problem with buying a complex item is information inequality. The seller knows more about it than the potential buyer. When inspecting the item, the buyer therefore looks for signs of hidden defects or for evidence that the item is in good condition overall. In this way, cleanliness becomes a proxy for the general condition of the object. Similar mechanisms are at work elsewhere too. Take job applications, for example. A sloppy application is a red flag, even if the applicant’s references are excellent.
"Information inequality" is known as "risk". Risk is inherent in any transaction. That factors into the price: one is willing to pay less the more risk there is, and will pay more for less risk.
Most "risks" have an upside and a downside. In this case, for example, the solar PV system may be working better or worse than the (potential) buyer initially comes to understand.
We have huge industries based on selling "risk, but with a huge potential upside" to people willing to pay for access to the potential upside. Many of those customers are not interested in low risk in that context.
So "more risk, pay less" is not a hard and fast rule, but depends on what is being purchased, the circumstances of the buyer, and more.
OT: a friend of mine recently bought a house. They were surprised to learn at closing that the seller had financed their solar panels and that wasn’t apart of the home purchase.
So they had to negotiate who was going to pay off the solar panel, and this all had to be completed before home sale.
The "before closing" does a lot of work here. It sounds like the seller made the disclosure when they were legally required to. This is pretty common in large purchases. First the buyer and seller agree in principle, then they perform their due diligence. Sometimes sales fall through at that last step.
If, hypothetically, the seller never disclosed the financing, then that would be an issue between the seller and the financer. At most, the buyer would need to allow the financer access to retrieve their property. The financer could then sue the seller for the buy-out cost and/or breach of contract.
As an aside, at least around here (USA), if you see a house with solar panels, it is a good assumption that they are financed.
> At most, the buyer would need to allow the financer access to retrieve their property. The financer could then sue the seller for the buy-out cost and/or breach of contract.
Nope, at least not typically.
Typically in the US houses are sold as-is unless it's noted in the closing docs. Everything in or on the house when you close is yours. The seller would be the one fighting with the financing company, as (again unless noted in closing docs) they would be considered fixtures and considered part of the real estate sale.
In the US, Real Estate Agent is a sink-or-swim job. There are a lot of barely competent real estate agents who go through the motions, but otherwise only superficially understand how to do the job.
For example, I run an HOA, and agents routinely forget, until the last minute, to come to me for the HOA's paperwork. The state even requires 10 days notice. I've switched to an attitude where I proactively reach out to the seller (not agent) early in the process.
Exactly the same reason you should probably clean the rest of the house when you're selling it.
Theoretically, the price of the house before cleaning should be equal to the value if the house after cleaning, minus whatever the cleaning costs. In reality, you'll get much less for your house without cleaning it, because human emotions.
We had a contractor doing repairs before we sold our house. Without being asked he took an orbital sander to the wooden hand railings along the stairs to the front door and said "people really notice this".
A family came for the tour and before walking in the father put his hand on the rail, looked up at the house, and said "this place seems well maintained". Then they bought the house after a small pleasant (for us) bidding war.
The contractor earned his high rate and then some.
A real estate agent told me that a customer decides to buy/not buy a house as soon as they put their hand on the front door knob. If he decides to buy, he'll look at the rest of the house looking for a reason not to.
I.e. putting in an expensive door knob is a good plan!
If I tour a house with pet urine stains all over the carpet, it's only logical to conclude that the owner is likely not maintaining the rest of the house to a very high standard.
It’s not just emotions, it’s a sign that, when presented with something annoying that you should do but not strictly required, it shows that you pushed through and did it anyway.
It doesn’t prove that you’ve been generally on top of things for the lifetime of the house but the inverse situation where you couldn’t clean one time for guests sure doesn’t.
There are other reasonable interpretations of such things. More precisely, one may simply care in different ratios about various things than is typical. For example, one may be fastidious with replacing furnace filters and water heater anode rods while not caring about their lawn beyond city or hoa mandates.
Having recently bought a house, I love thinking about things that increase perceived value relative to cost (more so because they're nice to have, not because we plan to sell any time soon).
A few things we changed right away:
- new mailbox (replacing a rusted 30+ year old one)
- lots of landscaping work (the majority of which I can do myself)
- installed a wine fridge (I always felt it gave the sense that the kitchen was upgraded when we were touring places)
- replaced old door knobs with modern matte black levers; ~$50 each
The house was built in 1968, so it's been interesting to think about all of the small things that make it feel dated that can be changed for not much money.
To add a few more: it's similarly easy to swap cabinet handles, vent covers, outlet wall plates. Fresh caulk is nice too, even if it's a bit sloppy, still beats stained or cracked caulk.
Those are things I've noticed when I've shopped for homes.
Mostly, I notice that they look like efforts that were motivated by trying to get a high price, but are limited to being fast and cheap.
So while I do note them, my perception of them is not generally positive at all.
I'd rather the outlet covers be original and clean than the new, usually oversized covers (with a slight color mismatch) I often find.
If I'm seeing caulk anywhere, that's problematic for me. When used properly-sparingly to seal things, it doesn't draw the eye at all. When it's used to hide sins, it's awful.
When I see sloppy caulk I first think of the time I'll need to spend to dig it all out. And then, I think about the time it will take to actually-fix whatever things it was hiding that nobody has ever bothered with actually getting right.
When I see new doorknobs on old doors, I'm mostly attracted to the outline that was left by the original hardware. And then I wonder: The old knobs were probably made from materials like steel, cast iron, and brass; stuff that can last for centuries with some maintenance. Why were they replaced?
Were the old knobs non-functional somehow, or were the owners too cheap and lazy to bother with taking things apart for a bit of TLC and preservative paint?
What other parts of the house were done fast, cheap, and/or lazy like a landlord who doesn't give a fuck? What haven't I found yet that they "fixed"?
It’s the faucets and sink fixtures that can jump out at me. I… question some of the Amazon-grade ODDALLCAPS fixtures’ ability to not spring a leak in the long term. Showerheads are more whatever.
And the rest of the plumbing. I'm not saying that homeowners can't plumb properly (many do excellent work), but: Too many times, it's just ugly.
Sometimes it's easy to find: The "soft" parts under the sink are a mess. Flexible pressure lines that are a mile too long, bendy pipes on the drain (this should never happen), traps in series with one another, bizarro-world TPCLALL-branded Amazon-sourced parts that simply do not match regulated norms at all and which haven't seen a UPC® logo ever... but that's simple to rip out and replace.
Sometimes it's harder to find. Drains that go uphill. A sea of CPVC pipes running in every direction, with dead ends, all buried in the basement ceiling. No trap for the bath tub upstairs. Mixed metals. Mixed plastics: PVC is fine, and ABS is fine, but mixing them together is bad (and shows that a trip to the parts store to get The Right Fucking Thing was just too much work, since it wasn't done). Bad or nonexistent venting.
The problems of today are caused by the lazy, quick fixes of yesterday.
Also make sure your screws in your outlet wall plates are vertical. I've found it's a key tell between mediocre electricians & handymen, and the real pros, and it gives me confidence (perhaps unfounded) that the electrical systems are in good shape.
That's funny - I always align the screws in the wall plates when I (re)install them, but imagined that to be an idiosyncratic bit of fastidiousness. I've never noticed anyone else having done it.
I hate when sellers do this. Replace all the finishes and hardware with the cheapest possible hardware from the store just because it is new. You end up paying for a top dollar house (because now you can argue its worth more than comps that didn't get this treatment) with bottom dollar components.
What would be better is not doing anything and letting the new owner install what makes sense to them, instead of having them pay markup essentially for these placeholder finishes, but obviously we can't have any altruism on this capitalist earth.
What is funny is it is kind of going full circle now with the home decor. All the 70s-80s era finishes boomers are currently gutting and replacing with builders special grey modern blegh are actually becoming popular again among millennials and gen z buyers.
i find it extremely hard to imagine that Donald Trump would have ever been personally involved in the sale of a vehicle at the level that he'd be making decisions about whether or not it was detailed, but I guess it's sensible generic advice
> In reality, you'll get much less for your house without cleaning it, because human emotions.
It's trust, because if the previous owners can't even bother cleaning it up, what else might their neglect have done to the house? Maybe I'll need to change the house wiring, verify if any new paint job is hiding mold or infiltration... All that is the cost of uncertainty and uncertainty grows with distrust.
It's not just emotions, it's also a matter of time and uncertainty.
I was in a buying situation where my old lease was expiring soon, I had a second kid on the way, and the last thing I'd have wanted is to buy a place where I'd have contractors milling around for weeks or months to make various repairs. I was willing to pay a hefty premium for a place that's in a move-in condition.
I don't think this extends to "you'll get $10k less if you don't vacuum", but it's a common courtesy on a million-dollar transaction to maybe not leave a mess.
Being rational about this (i.e., buying a dirty or otherwise manageably flawed house) is a great way to save or make money in markets where the majority of the cost is the building.
See also why houses are often painted when being staged for selling just so that the new purchaser can paint immediately after with their preferred colour. Wasteful but it works.
People always want to make a place their own with renovations, which means a new bathroom, a new kitchen, a complete lick of paint and the list goes on.
They would prefer to throw out an old suite rather than something that has just been fitted to 'sell the house'. The excuse is provided for them to make it their own.
What they don't want is filth. A spotlessly clean house is preferable to one that has been hastily tarted up with a quick lick of paint. It is respect for the buyer.
It's perfectly rational to assume someone who didn't bother to clean the house before selling probably didn't take good care of the house in other, less visible ways.
I spend €125 on an interior decorator and another €500 in furniture and decorations after to make my condo more cozy. And then another €300 for professional photos and drone shots.
The photos looked like those fancy interior magazines. I will never know if it is because of my effort and investment but I’m certain that it attracted a lot of attention. People really want a move-in ready home that looks like the magazines.
I agree. Doesn't matter what you sell, you will get a higher price if it is cleaned and tidy when presented to the market - because the kinds of people who pay higher prices are looking for clean and tidy things.
Exactly. "Is it clean and tidy right now" is a decent proxy for "Has this been properly taken care of in the past"
Obviously it's not infallible. But even if the owner only cleaned their stuff now that they are selling it that still tells you they are the type of person to take action where it's beneficial
I think it's more of a negative indicator. It's like turning up to a job interview wearing dirty clothes - unless you're a savant it's probably indicative that you don't give a shit or have some sort of other problems in life. But wearing clean clothes doesn't give you points because it's assumed to be the norm in that setting.
> "Is it clean and tidy right now" is a decent proxy for "Has this been properly taken care of in the past"
I don't think so, esp at selling time, I definitely expect that the owner has just made it look pristine. But the opposite is definitely true: if you can't even bother making it look clean and tidy when trying to sell, I'm pretty sure you've not taken care of it in the past!
Definitely. On the other side, if you can't even bother to clean it before you sell it, I have no reason to believe you've put any effort in maintaining it.
Cleaning in general is also usually a core part of maintaining something. Dirt and grime lead to wear and tear.
Wikipedia is written by various people, but likely someone with interest in a given topic. One or more realtors probably wrote or edited this post.
Actually, the history of edits shows that this is contested territory where people regularly remove what they term as spam links. So, while a disinterested editor might remove a link to a listicle about how to stage your home, they might leave in the breathless tone as harmless. The drive by editors probably feel that they have no more time to rewrite it than we do, given that they watch over many articles, not just this one.
I have a 19 year-old, roof mounted, 6.3 kW nominal system in two arrays (east/west facing), 40 deg. north. I've never washed the panels outside of rain and occasional hail storm "scrubbing". Replaced a failed inverter two years ago.
My peak summer output is basically the same as when installed, making 36-38 kWh on a cloudless day. I'm actually impressed my panels haven't really degraded in performance over those 19 years.
That's really impressive and well built solar system, for it to last thta long. It shows how durable quality panels are. I have a 6 month old ~3.7kW system (6 panels in total), planning on installing another 6 very soon. My house is surrounded by trees so it's been a bit of a struggle in the winter.
Panels should do 30 years, easy. Inverters will usually fail after 15y, and with batteries it’s unknown what the current gen will do - 15y, maybe 20? Definitely get LFP.
My latitude plus east/west arrays are a struggle anyway. On the best (presumably cloudless) December day, I got 13.98 kWh. My 12/1/2025 through 1/31/2026 average per day was 10.32 kWh.
SolarWorld, 175 watt, polycrystalline. I don't recall any model number (paper work is filed away somewhere.) ISTR mine were made in Germany. I think at the time my system was installed, there where some 225 watt panels available, but the 175 ones were a better price point per watt.
Prices per watt of solar have fallen by so much over 20 years its absurd. You can probably buy the best and/or most costly residential panel on the market and still come well under whatever the median was 20 years ago. Probably well under a few standard deviations below the old median I'm guessing.
Re: the slightly strange shape of the curve. The drop at the beginning could be due to the matching between the panels getting worse. Solar panels in a bank don't like being in different conditions. As a rule of thumb they will all perform at about the same level as the worst in the bank but at the finer levels you could get less straightforward interactions.
The drop off after cleaning could well be because some of the initial boost could come from the water cooling off the panels: solar panels become less efficient at higher temperatures so the drop of after they're all cleaned could be them warming up again after the water has evaporated.
> The drop off after cleaning could well be because some of the initial boost could come from the water cooling off the panels: solar panels become less efficient at higher temperatures so the drop of after they're all cleaned could be them warming up again after the water has evaporated.
This was almost certainly the case. AIUI, that cooling still makes a large difference.
Makes me wonder if it is worth it having a small esp32 or similar control a sprinkler system for the panels. Keep them cool during high ambient temps by spraying a litre of water on each panel every 30m.
An idea I had a while back (when I was considering panels) was running my mains water through the back of each panel (before the mains got to the hose) in a sort of radiator pattern.
People make the same claims about cleaning their air conditioner. Yeah it’s blowing cooler inside: you’ve just chilled the condenser and left some residual evaporative cooling.
Yeah, came here to say this. There are a lot of things that will affect efficiency and how clean your panels are is only one of them. How dirty your panels get is also highly sensitive to both location and installation. All of this gets horribly confounded by string inverters (especially if they're clipping the peak, which they often are).
I easily see 5% increases in efficiency after cleaning (with micro inverters), but also see ~3% increase in output on a hot day from just spraying the panels with water to cool them off, which goes away in 15-20min.
If you're going to clean once a year, do it after the "last" rain of the year before summer peak solar output. If you live somewhere rural with summer thunderstorms, with high angle panels, and without a lot of pollen (or dust storms), you may not need to clean them much at all.
If you're going to climb on a roof, do it safely! A 10' fall can kill or maim you.
Was just watching a video about a guy who has a boat that runs on solar power that he drove all the way from Finland to the Mediterranean in Winter. Obviously in the winter he was charging his batteries using shore power. But since spring he's been running on solar power doing long journeys and maxing out at 5-8 knots. He just cleaned his panels. Lots of salt, dust and sea gull shit. Also a few kids dropped a rock on one of his panels. Cleaning them improved performance by about 10%. Not nothing. But they were really dirty.
It's a bit worrying the author is asking chatgpt about the tingle rather than making sure there's a grounding lug on all the panels and they're all bonded to a grounding rod.
The rudimentary nature of the setup makes me think there isn't something like a single conductor 12awg (or euro equivalent) copper wire that bonds to all panels and a basic $30 rod.
Eh, compared to what though? Compared to speaking to licensed electrician, definitely. But compared to doing a raw web search and trying to put the information in the right order for the application you’re currently working on, I think it’s at worst a wash.
There are many different ways to connect solar panels to the inverter. Usually the exposed metallic parts will be “grounded” (bonded to the ground / protective earth / equipment grounding conductor / whatever your jurisdiction calls it at the inverter).
But this is an array that looks a bit remote from any structure, and even if the electronics themselves are utterly, perfectly safe, the bonding wire will cause the panel frames to be at the potential of the inverter’s ground, and the soil will be at whatever its local potential is, and this may be different, resulting in a “touch potential”. You can mitigate this with a supplemental ground (or whatever your jurisdiction calls it) closer to the panels. There are fancy ways to do this particularly well to improve safety in the event of a fault.
If you are contacting the actual power wiring of the solar array, something is wrong. If you are feeling capacitive coupled current from the power wiring of the array, then I imagine this means your inverter has crappy filtering, and again the only way you would feel it is if the panel frame isn’t at the same potential as the local soil.
Oh, and if you live somewhere prone to lightning, you probably want to give a possible lightning strike to the panel a better route to a high quality ground than through the bonding wire to your house.
(In fact, in many parts of the world, including IIRC 48 US states, the power utilities may operate their distribution networks with a current carrying wire (combined neutral and ground) that is grounded at multiple points along its route, which will generate substantial leakage current through the ground. The exceptions are IIRC California and Wisconsin, and IIRC those states have their rules to help protect cattle from becoming part of an undesirable circuit while being milked. In CA at least, all the distribution transformers on the poles have at least two bushings on the primary side, and this is why. I believe this is California General Order 95, rule 33 [0].)
You’re allowed to add auxiliary grounds per NEC 250.54, they don’t do anything but you can certainly add them
> Oh, and if you live somewhere prone to lightning, you probably want to give a possible lightning strike to the panel a better route to a high quality ground than through the bonding wire to your house.
That’s what a surge protective device installed in your service entrance is for.
Horses for courses. My system is off grid, so any extra power is just not used, and its designed in a way that a 2-5% change doesn't do anything. That might be a more meaningful change if I were selling power to other folks.
Kind of off topic, but I see a lot of folks proximate to me have built systems to turn panels so they face the sun more closely. I can see the use in that if you don't have much space or if you have a large commercial operation, but this area is very rural.
My array (4kw) which I built myself has 10 400W panels. The panels cost me $1200 because the minimum order is 12 and the supplier suggested buying extras; shipping large panels one at a time isn't cheap. In fact, the shipping for the entire system (about $5000 worth of equipment) was almost $1000.
But my feeling is that for the cost of a moving array that tracks the sun / time of year would have cost quite a lot more and have involved construction that I personally wasn't comfortable with. The conclusion I came to is that it would cost about the same to build a second array, angle it for "summer" (mine is angled to be most efficient in winter), and hook it to the other MPPT on my controller.
That would take up a lot of space, but a) I am 40 acres and b) then I could run a mig welder with impunity during the day...
A lot of these designs are an artifact of a time when the panels themselves would have been far and away the most expensive component in the system. The place I'm in originally had 10 125W panels that probably cost north of $8k when installed, and they were mounted on a rotating, tilt-adjustable post. Also the entire house was wired to run off DC as much as possible, with three different wiring schemes throughout and rare & expensive appliances. It reminded me strongly of RV power schemes, and maintenance was probably a huge headache.
I replaced it all with 9kW worth of panels (about $3k, shipped) on 4 simple 60° ground mounts, normal wiring and appliances. Angle is optimized for early spring / late fall - there's effectively no sun in winter, and the rest of the year I have excess power even with fixed, sub-optimal angles.
The diminished cost of panels alone over the past 20 years has transformed "off-grid" from a pastime for wealthy hippies into a reasonable solution for remote living.
It does no longer pay to be clever with solar panels; they're too cheap. Angle not quite right? Add a couple extra. Summer vs. Winter? Add a couple extra.
My 6.7kW system produces 2.5 what we need in the summer, and 0.5 of what we need in the winter (even though its output here in New Mexico is relatively constant). Adding a couple extra is going to accomplish nothing in the face of a winter heating system (even with high efficiency heat pumps).
You don't get "classed as an energy company", you just have to pay taxes on the money you make from selling the energy. This starts at 30 kWp (up to that size, the income is tax free), which is very likely more than what you could put on a private home.
well I mean okay, but it happened to me, and i had to pay a lot to an accountant to do this paperwork and i resent it utterly. I guess it’s unpopular here to be dissatisfied with the insane bullshit tax system in this country.
I didn’t make a profit, it’s not commercial — but apparently getting to almost break even on my energy bills is a “profit”.
Your post sounds like there is some strange rule regarding taxation of solar installations, but it is (or rather was) just treated as any other income from commercial operation.
- If you have any income from commercial operation (selling stuff) you are required to declare that, when doing your taxes.
- When selling electricity you're not so much classified as an energy company, but fall under similar taxation rules as a company. This also means you can get the VAT back, you paid when buying panels, inverters etc.
- Since 2023 solar installations smaller than 30 kWp are completely exempt from this taxation scheme. This means you're not paying any VAT, when buying equipment for your solar installations and don't have to declare the revenue.
- You can get around the 30 kWp limit under some circumstances by having multiple separate installations.
- Parent post is talking about an off-grid installation, which would be exempt anyway, because there is no revenue from selling electricity.
The tax exemption from 2023 was a very welcome move by SPD and the Green party to reduce bureaucracy regarding solar installations and I think the 30 kWp is pretty reasonable
Would be interesting to see, how other countries are handling this.
Washing solar panels is one of the current popular business ideas on social media. It’s an easy pivot for anyone who already has some experience with much harder home repair handiwork involving a ladder.
The reason it’s popular is because most people don’t understand the economics at all. Someone can go door-to-door in a neighborhood offering to clean solar panels and making huge claims about improving efficiency so much that you can’t afford not to do it.
Homeowners who invested $30K in solar panels think of a $300-600 charge as an easy choice to keep their investment producing money.
My parents had someone going around their neighborhood trying to charge $50/panel for cleaning. They didn’t even climb a ladder. They sprayed washing solution from the ground. Most neighbors declined, but you could see the guy spraying down a couple roofs.
Easy way to clear $1000+ per day for knocking on some doors and pointing a hose at a couple rooftops, at least until the public figures out the scam.
I asked a friend with a window cleaning business and they charge about $10 a panel. At that rate I'm tempted to try it but I'm not sure if it's even worth that.
Maybe the thing to do is to NOT upgrade existing working panels but rather set up a different/separate entity with completely different accounts and new panels?
And about the washing, I wonder if it would be worth it to automate the process with a spray of water periodically? You can still wash the panels but I suspect it won't be necessary if there isn't too much dust accumulation? Isn't rain supposed to wash away the dust? What am I missing here?
It may also be worth spraying them with water when they are too hot. As they get hotter the efficiency drops a little. It's only a few percent, and usually it happens at the time you need the efficiency the least because it's sunny, but if you can combine cleaning and cooling and get a few extra w out if it, why not.
Solar panels are increasingly being oriented east or west instead of south, as while it reduces overall yield, it maximises power when it's needed the most - during morning and evening peaks.
I don't have numbers, but I suspect it alleviates issues with dust buildup and temperature.
The most interesting trackers to me, for DIY install in my yard, is a 2-axis tracker. Especially in summer, sunrise and sunset are quite a bit north of east and west, meaning a true south facing fixed set of panels wouldn't even see the sun yet.
Sadly, my investigations a few years back indicated that a suitably strong and robust 2-axis tracker that would withstand our local winds and snow loads is significantly more expensive than just buying more panels and facing some of them east/south/west to accomplish the same thing. Doing this on an existing shed also avoids some local zoning rules vs a dedicated ground mounted system.
I get the impression they are getting less viable because the extra cost and maintenance outweighs just putting more panels down. There are some calculations that suggest even mounting them on angled frames might not be worth the cost, depending on how dirty they get when you just lie them flat on the ground.
(This assumes that you have enough space, but for grid-scale solar this is not the limiting factor. The costs are roughly in order from most to least: the cost of the inverters and grid connection, the cost of installing the panels, the cost of the panels themselves, then the cost of the land to put them on)
I can speak to this somewhat. My panels are on adjustable frames. Typically I switch from flat (summer) to tilted (winter).
As always ymmv and depends somewhat on your location. I'm around 30 degrees from the equator.
During summer, lying flat gets a lot more power. And more importantly the start and end of the generating period is longer. Ie the panels get more sun in the morning and evening thankfully they were tilted.
In winter the sun is more "from one direction" and obviously is lower on the horizon.
Storage is one way to move time of supply to match time of demand. Offsetting the time of supply directly is simpler, although it probably doesn't offer a complete solution.
The upcoming "balcony solar" legislations will allow up to a limit (iirc 1200W in Virginia) of solar to be directly be connected to the electricity outlets of a house to make our electricity costs lower without having to pay for a battery from what I understand.
Yes, I meant I can get on board with automatically (periodically or based on some trigger or sensor) spraying the panels with water but I was hoping it isn't necessary to use Windex® or even dish soap on the panels themselves.
> You can still wash the panels but I suspect it won't be necessary if there isn't too much dust accumulation? Isn't rain supposed to wash away the dust? What am I missing here?
In places where solar panels are used the most, like the Southwest US, there isn't much rain to speak of. Panels get a lot of dust accumulation from Feb-Nov typically, just when they're needed the most.
The author had ground level access. In that case, A microfiber covered sponge on a pole with a 5 gallon bucket of soapy water is probably the easiest thing. Especially if you do it annually, the dust wouldn’t be completely caked on requiring scraping and excessive elbow grease.
I do a similar procedure for my house windows. I use a squeegee on those but probably not necessary for panels.
In the southeast states in the US, we experience "the pollening" each Spring, which can leave 1/8" or more of thick crusted pollen on solar panels. I wash ours at least monthly March through May. They're at least 15-20% more efficient, if not more, without the pollen crusted on them.
I clean my solar panels, 7kwh, every monmth or two.
When I check on the VRM portal it makes a difference, and since I am so dependent on them all year round, I have no problem giving them some attention from time to time. Ten mins well spent.
I have 4kw of panels and 15kwh of storage. I only get down to about 80% most nights (I heat with wood and propane).
But my system will charge completely in about 2 hours of full sun. If it took 3 hours it wouldn't make a difference. So I generally don't clean them (well, the rain and snow do that work).
I do remove snow, because that has a very noticeable impact.
Is the difference that you are pushing back to a grid (I am not), so the power all gets used regardless of you being the one to use it?
I'm off grid, no mains power, and have 8x48v lithium Fogstar batteries in an external rack, since my cabin is small.
On December 21, due to trees, my panels get around 2 hours of full sun, if the universe smiles on me.
I use around 5-6kwh per day, if I use my computer, which I need for work.
This will be the first year with the fogstar batteries, previously had 1x48v generic lithium battery, but last year I used the generator most days from around end of november until March e.g. December
consumption was 153kwh, solar generated 62kWh, and generator made up the rest.
This year, thanks to having more storage, we'll be better able to take advantage of sunny days and capture more power. I also have a freezer and washing machine this year :-) Ask me in March how it went.
All of my panels are easy to access, none on a roof, so the effort is minimal and has non-zero power benefits in my experience.
I should add that I am surrounded by trees and the panels accumulate a green tinge quite quickly, plus bird shit.
> I also have a freezer and washing machine this year
You need a heat pipe between your freezer/fridge and outside. Then it will “function” when it’s colder outside than in your fridge and otherwise sit idle(ish). Sure you’re bringing “cold” into your big warm box (home), you have wood to overcome that. All theory, but it makes sense in my mind!
(Though in most places, it rarely gets colder outside than in your freezer)
Roof-mounted solar panels are a necessity in urban situations but they are a maintenance nightmare compared to a ground-mounted array. That has to be accepted as "the cost of doing solar" when there is no other alternative.
Our peak daily export energy jumped by about 35%-40% when we had our panels cleaned for the first time in 8 years. They _look_ much cleaner, and the measured export shows it.
If export energy is 10% of your total output, and it jumped 35% then you got a ~3.5 - 4% gain in total output, not far from the author's experience.
Of course, you can math that any way you like to make the numbers bigger or smaller, depending on whether you're representing the buyer or the seller of the system.
It's not 10%, it's much more than that. I'm obviously comparing the peak values, which tend to be days when we don't consume much, which might mean a background 100W vs a couple of kW peak generation. I can dig deeper into the per hour generation and it's similar.
> This is the yin and yang of market-distorting incentives. Today's incentive to install solar becomes tomorrow's disincentive to upgrading it.
Facing this as well. We've got our 5.2kW system in a pile in our yard as the house is being enlarged, new roof going on, etc. We're switching from a gas furnace to a heat pump system, and will also be installing a hot tub. I'm sure our annual power bill will double from say $1k to $2k, but it doesn't make sense to enlarge our system.
I'm 8 years into a 20 year net metering scheme (NEM2.0 in CA), and any changes I make will kick me off the plan. In theory I am allowed to add up to 10% or 1kW, but in practice my solar company keeps telling me it's not worthwhile. I think the paperwork and administrative burden of even adding the amount I'm "allowed" to add just means it's not cost-effective.
Whether or not the utility actually would notice that I'm mysteriously getting 1kW additional generation (if no paperwork was filed) is another story.
> If I increase the power output of the system then the additional capacity will not be eligible for the feed-in tariff and will revert to present-day prevailing tariff which is about 4x worse before you even consider that I currently get to use electricity and still get paid for generating it.
> This is the yin and yang of market-distorting incentives. Today's incentive to install solar becomes tomorrow's disincentive to upgrading it.
I am not sure what author is trying to hint. But solar does not need artificial subsidies, and can pay for itself!
There are no subsidies in UK! Homeowners get so much money, because of all that sunshine and wind energy, their house generates! UK goverment just run out of money, when energy got expensive!
UK goverment needs to step up, to replace gaz with renewables!
You can not expect homeowners to sell energy bellow market price!
> solar does not need artificial subsidies, and can pay for itself
That's true now, but wasn't true when those panels were installed. There were subsidies available to get the market kick-started.
They consist of an extra payment for every kwh you generate on top of the payment for delivering the power to the grid. The amount varied depending on when you signed up to the scheme, but at certain points it was as much as 50p/kwh (+ inflation, so more than that now).
> I am not sure what author is trying to hint. But solar does not need artificial subsidies, and can pay for itself!
At grid scale, yes.
For the house, not so much.
The feed in tariff was at one point 41 pence per kwhr which is probably £10 a day in summer.
but at 12p a kwhr it drops to £3.6
However, 10kwp of panels is ~£1800, but the micro inverters needed to drive them are >£3k (as its outside you can probably use two larger inverters.) Then mounting system is probably a good 800 quid too.
Solar gets lots of subsidies in the UK. Homeowners who installed it 10 years ago get a ridiculous payment for generating excess, even if the grid doesn't use it.
> I am not sure what author is trying to hint. But solar does not need artificial subsidies, and can pay for itself!
I think he is describing a subside that some governments gave years ago: you installed for example 5K, and get paid for whatever they generate at 300% market price, for a long time (25 years?). Today you find out that upgrading panels would made perfect financial sense, if you were selling at 100% and are going to sell electricity at 100% (you will be doubling the output for a tenth of the inversion 15 years ago), but as the subsides of 300% no longer exist, you will be actually losing money by upgrading.
That's not true. You can upgrade to the same capacity on the previous feed-in tariff and keep what you had. It makes sense to upgrade as you can then fill the extra space with additional panels (which will not be on the old tariff, but can be a separate system).
when it first started it was basically 450GBP/MWh (In 2010 GBP). and that was paid for every kWh generated (whether exported or not). And the PPA lasts for 20-25 years.
There’s this viral video on X of a guy at an Alex Hormozi talk saying he makes money cleaning solar panels… and it’ll probably turn into a whole market. If he’s getting 2% to 5% gains, I can already see marketing blowing that way out of proportion
Appreciate the attempts to quantify it. I haven't tried to quantify washing, but I do look at mine regularly. I doubt anything accumulates that rain doesn't handle well enough.
Messing around with ground panels is lower risk and safer than roof panels where tool extenders and ladders start to become involved. If you have roof panels, you are the biggest danger to your panels (and yourself.) Don't try to clean them, spray them, knock snow off of them. I was told this multiple times by my installer. :)
As another anecdata-point, when we did this for a now already fairly old roof installation of about 15kWp, it was more than “just about worthwhile”, since the panel area is contiguous: cost seemed to scale up less quickly than the wattage/theoretical maximum output, and the cleaning guy (solo company, IIRC) even told us it wasn’t necessary to do this every year (we hadn’t had it done even once the first decade+ of the installation’s lifetime).
In many countries it is actually illegal to use tall ladder etc. owners would have to erect a scaffolding to make access for work people to clean it safely.
There are definitely some wacky nanny state rules out there… but I’m a little skeptical of “In many countries it is actually illegal to use tall ladder”
Probably the GP meant to hire people and order them to use a tall ladder. I don't think there's any country where it's illegal for you to use one outside of some kind of contract.
Tradespeople are typically independent contractors. You hire them to do a task, and they use their own judgement on which tools to use. You don't order them to use a tall ladder...
So if it's a 2-5% increase, barely break even, it more than breaks even during an extended power failure if you live somewhere this is likely. There are a lot of things I choose to do to avoid future timelines where 'sus appliances break at the worst possible moment. This would be along the same lines to me. Your mindset may vary YMMV.
Nobody can answer this. It simple depends on each setup. Some panels will get incredibly dirty quick like those in the south west where there may be a lack of rain and lots of dust but in other regions you may never need to.
There are at least a couple of outfits claiming a nano coating or a nano glass surface for solar panels that are so smooth as to not collect dusts. Their other claim is greatly improved angular photon capture since the panel is just that flat. The two companies I've seen claim ~20% improvement - and less maintenance.
20% seems high enough that if it was really _that_ effective, the companies making the panels would be tripping over themselves to buy this coating to apply it to the panels right in their factories. (And charge a premium for it.)
My solar panels are leaning in stacks in my yard, as our house is currently being removed with a new roof, etc. I'm planning on cleaning them while they're "loose", but I wonder if it also makes sense to apply a(n automotve-style) ceramic coating to them.
Given the angle of a panel should match its latitude and average sun angle, the panels might generate noticeably more by being pitched steeper at over 30 degrees. Eyeballing this, it appears closer to 25 degrees right now which doesn't even make sense for the summer sun in the UK. I could be wrong as it also appears these are on a slope!
Of course washing them makes sense, physics-wise. As others have pointed out, you are almost certainly seeing a rise due to cooling off the panels (this would not make economic sense to do all of the time). Temperature has a pretty dramatic effect on solar panel output. Cooling a panel can boost production by 10% or more. Do not polish them. Solar panels are designed to be anti-reflective. You don't want a shiny surface.
But, the real factor in all of this is how valuable the time required to clean the panel is.
On Mars, the wind storms and dust devils are so fearsome that some of the robots there could rely on dust being blown clean off all the solar panels on a regular basis. Spirit and Opportunity benefited the most from these effects.
InSight was stationary and not so fortunate. But, the ground team got quite creative with its robotic arm to try and manipulate the sand that had accumulated on the solar panel, and gained a little bit more power.
I haven't noticed too much of a power increase in my backyard solar farm after cleaning, but I do notice a very significant increase by weeding the surrounding stuff. Even a pretty small amount of shade will very significantly reduce your yield, like seriously 20-30%.
Oh, also, I've noticed that at least with my panels, bird poop seems to be particularly bad. The dust that accrues doesn't seem to do much, but even a relatively small bit of bird poop will be almost as bad as weeds. Fortunately it's not terribly difficult to clean once it's dried.
Yeah, the one tree branch that hits my array until 10a prevents it from charging at all even though it only obscures 1/4 of one panel in the 10-panel set.
But I like the branch and have plenty of full sun, so I haven't cut it.
Rain usually just cakes the dirt. Unless it's a downpour, it doesn't move with enough velocity or volume to remove the dirt. So the dirt just gets damp, maybe moves a few cm with gravity, then dries as a mud cake.
See this all the time in Phoenix metro: A light rain just pulls down all the dust in the air and deposits it on the car. It has to be fairly sustained to wash away the initial dust collection, and even then you can still see dust on the paint.
However if you are using a string inverter you will want to wash all the ones on the same string in one go if you can, you don't really want them generating different voltage or you will miss out on a lot of power.
I'm surprised that the outcome was not much greater improvement. I'm glad though it removed one of my concerns about solar. I'm glad cleaning maintenance really is not really needed.
If you feel "a tingle" when touching solar panels, that means there's a ground fault, a wiring short, or a missing ground wire. This is incredibly dangerous as solar arrays carry hundreds of volts.
Question for people here: my local power company charges a fee if solar is attached to the grid and is high enough to make installing residential solar impractical.
I'm thinking the best thing to do would be put a large battery in between the grid and my home and selectively recharge the battery with the solar. I believe that setup circumvents the fee since the only thing using energy is the battery, as though it were an off grid setup. I might consider not putting the entire home behind the battery but just the largest energy hogs, like the HVAC or others.
Does this make sense, are there existing setups like this and what are thoughts about something like this?
Without trying to answer your "I believe the setup circumvents the fee" implied question, which you should find an actual answer to...
See reddit's r/solarDIY. There are a lot of setups like this, either for full house power or partial. I have a relatively big server in my basemeent that I power this way, for example, with a battery system that acts as both UPS and a "charge the battery from solar and run off inverter when possible". Something like an off-grid EG4 is popular among the reddit crew as a way to manage this; the device tries to run locally but accepts a shore power feed from the grid so if you need it you draw grid power. No grid tie involved.
> I believe that setup circumvents the fee since the only thing using energy is the battery, as though it were an off grid setup.
Entirely based on your jurisdiction, but that kind of zero-export requires the same permits and connection fee as a full net metering in mine. You can't end run the process by just being sneaky, electrical work needs permits and they'll either make you take it out (!!) or bring it into full compliance.
As an example, my utility is one of those ones that requires a separate manual disconnect, even though the vast majority of all-in-one inverters have a built in disconnect. It doesn't make any sense and it's at least two grand in permit + equipment, but that's the rule.
Having just put a battery into my existing system. For the power company I use the answer is no to your question. Many power companies charge that fee depending on the size of panels. Now if you do not hook to their system they do not care (off grid). But if you plug into it then they care and charge for the privilege.
Now you could pull particular items out of their grid. Just need the wires and panels to make sense. They would not care about that either. It is only if the panels are plugged into the grid they start to care. Downside is sometimes waiting for that battery to have enough juice to work. It goes faster than you think and some battery systems are decently expensive just by themselves, on top of the panels/inverters/controllers/install.
Because often the law cares about intent, not technicalities. Technically you could argue that this is a "whole home battery solar setups with a grid backup", but clearly the intent is as a workaround.
I'm not saying this is bad. I love a good workaround for onerous laws & fees, but random Internet commenters aren't the best at determining what workaround will or will not pass muster if a judge gets involved.
Like someone said in another recent thread: "U.S. law though is highly non-autistic and what you were trying to do is just as important as what you superficially did." https://news.ycombinator.com/item?id=49064242
That depends on what options are available to you for residential solar installation. Installing solar panels + micro-inverters is very cheap in cost of parts, but possibly expensive in labor. It will easily pay off your grid interconnect fee every month once you hit break-even from operating for a few years. Financing vs cash, cost of installation, tax credits, are the biggest factors in how quickly it becomes profitable. If you are extremely handy you can DIY most of it as a homeowner (depending on local/state laws) which cuts costs significantly.
You can do a whole home backup + solar panel input (aka ESS+PV) but it's much more expensive in parts and installation and is more complex. If you don't add grid interconnect it can be much cheaper as you can use "off-grid" parts (grid interconnect requires more expensive parts certified for certain standards).
But some jurisdictions may not allow cheaper "off-grid" parts/systems to be connected to the grid, even downstream. So an alternative would be to install a transfer switch, where you manually switch from the grid to off-grid. But then you literally have to choose whether you use the ESS+PV or the grid at any given time and manually throw a switch (you can't use grid to charge your system). And yes you can set this up for only specific circuits/appliances. Again it depends on your state and local laws.
AI can do most of the research for you. Keep a Git repo and add documentation and details to it over time, and you can build up an analysis of what works for you based on all available options, price comparisons, energy requirements, and local/state laws. It is unfortunately quite complicated because there are many options but not all will apply to your location. And before you do any of this, do a solar site survey to see if you can even reliably generate enough power from the sun!
> why would you clean them when you're about to sell the house?
So they look good and the potential buyer sees something that looks to be in good condition and working well.
I would generalise this a little: The problem with buying a complex item is information inequality. The seller knows more about it than the potential buyer. When inspecting the item, the buyer therefore looks for signs of hidden defects or for evidence that the item is in good condition overall. In this way, cleanliness becomes a proxy for the general condition of the object. Similar mechanisms are at work elsewhere too. Take job applications, for example. A sloppy application is a red flag, even if the applicant’s references are excellent.
Aka: a heuristic: https://en.wikipedia.org/wiki/Heuristic
"Information inequality" is known as "risk". Risk is inherent in any transaction. That factors into the price: one is willing to pay less the more risk there is, and will pay more for less risk.
Much too simple.
Most "risks" have an upside and a downside. In this case, for example, the solar PV system may be working better or worse than the (potential) buyer initially comes to understand.
We have huge industries based on selling "risk, but with a huge potential upside" to people willing to pay for access to the potential upside. Many of those customers are not interested in low risk in that context.
So "more risk, pay less" is not a hard and fast rule, but depends on what is being purchased, the circumstances of the buyer, and more.
OT: a friend of mine recently bought a house. They were surprised to learn at closing that the seller had financed their solar panels and that wasn’t apart of the home purchase.
So they had to negotiate who was going to pay off the solar panel, and this all had to be completed before home sale.
I'd expect solicitors to find liabilities like that. How did it end?
The "before closing" does a lot of work here. It sounds like the seller made the disclosure when they were legally required to. This is pretty common in large purchases. First the buyer and seller agree in principle, then they perform their due diligence. Sometimes sales fall through at that last step.
If, hypothetically, the seller never disclosed the financing, then that would be an issue between the seller and the financer. At most, the buyer would need to allow the financer access to retrieve their property. The financer could then sue the seller for the buy-out cost and/or breach of contract.
As an aside, at least around here (USA), if you see a house with solar panels, it is a good assumption that they are financed.
> At most, the buyer would need to allow the financer access to retrieve their property. The financer could then sue the seller for the buy-out cost and/or breach of contract.
Nope, at least not typically.
Typically in the US houses are sold as-is unless it's noted in the closing docs. Everything in or on the house when you close is yours. The seller would be the one fighting with the financing company, as (again unless noted in closing docs) they would be considered fixtures and considered part of the real estate sale.
I've heard it's pretty standard, their real estate agent should know that (and tell them about it on their first visit).
In the US, Real Estate Agent is a sink-or-swim job. There are a lot of barely competent real estate agents who go through the motions, but otherwise only superficially understand how to do the job.
For example, I run an HOA, and agents routinely forget, until the last minute, to come to me for the HOA's paperwork. The state even requires 10 days notice. I've switched to an attitude where I proactively reach out to the seller (not agent) early in the process.
Actually in some places panels devalue a house because some people consider them an eyesore
I believe this will pass as people get used to them as part of our modern world.
Exactly the same reason you should probably clean the rest of the house when you're selling it.
Theoretically, the price of the house before cleaning should be equal to the value if the house after cleaning, minus whatever the cleaning costs. In reality, you'll get much less for your house without cleaning it, because human emotions.
We had a contractor doing repairs before we sold our house. Without being asked he took an orbital sander to the wooden hand railings along the stairs to the front door and said "people really notice this".
A family came for the tour and before walking in the father put his hand on the rail, looked up at the house, and said "this place seems well maintained". Then they bought the house after a small pleasant (for us) bidding war.
The contractor earned his high rate and then some.
A real estate agent told me that a customer decides to buy/not buy a house as soon as they put their hand on the front door knob. If he decides to buy, he'll look at the rest of the house looking for a reason not to.
I.e. putting in an expensive door knob is a good plan!
There's a reason the three most important things in real estate are "Location, location, location"
None of those are "door knob, door knob, door knob!"
Also make sure the door operates smoothly and is well-aligned.
Certainly wasn't the case for any of the houses I've bought. All were compromises in various ways; none were houses we loved on first sight.
Have you ever driven by a prospective purchase and never bothered to get out of the car?
> All were compromises in various ways
That's true of just about everything.
No, we never saw anything we didn't at least look at. We had spent the time to go to the place, might as well look at it.
Did we rule out places based on photos/descriptions? Yes, certainly.
> because human emotions.
If I tour a house with pet urine stains all over the carpet, it's only logical to conclude that the owner is likely not maintaining the rest of the house to a very high standard.
OTOH, spotless carpets do not really tell you the opposite is true. Just means the realtor doesn't suck.
It’s not just emotions, it’s a sign that, when presented with something annoying that you should do but not strictly required, it shows that you pushed through and did it anyway.
It doesn’t prove that you’ve been generally on top of things for the lifetime of the house but the inverse situation where you couldn’t clean one time for guests sure doesn’t.
There are other reasonable interpretations of such things. More precisely, one may simply care in different ratios about various things than is typical. For example, one may be fastidious with replacing furnace filters and water heater anode rods while not caring about their lawn beyond city or hoa mandates.
Having recently bought a house, I love thinking about things that increase perceived value relative to cost (more so because they're nice to have, not because we plan to sell any time soon).
A few things we changed right away: - new mailbox (replacing a rusted 30+ year old one) - lots of landscaping work (the majority of which I can do myself) - installed a wine fridge (I always felt it gave the sense that the kitchen was upgraded when we were touring places) - replaced old door knobs with modern matte black levers; ~$50 each
The house was built in 1968, so it's been interesting to think about all of the small things that make it feel dated that can be changed for not much money.
To add a few more: it's similarly easy to swap cabinet handles, vent covers, outlet wall plates. Fresh caulk is nice too, even if it's a bit sloppy, still beats stained or cracked caulk.
Those are things I've noticed when I've shopped for homes.
Mostly, I notice that they look like efforts that were motivated by trying to get a high price, but are limited to being fast and cheap.
So while I do note them, my perception of them is not generally positive at all.
I'd rather the outlet covers be original and clean than the new, usually oversized covers (with a slight color mismatch) I often find.
If I'm seeing caulk anywhere, that's problematic for me. When used properly-sparingly to seal things, it doesn't draw the eye at all. When it's used to hide sins, it's awful.
When I see sloppy caulk I first think of the time I'll need to spend to dig it all out. And then, I think about the time it will take to actually-fix whatever things it was hiding that nobody has ever bothered with actually getting right.
When I see new doorknobs on old doors, I'm mostly attracted to the outline that was left by the original hardware. And then I wonder: The old knobs were probably made from materials like steel, cast iron, and brass; stuff that can last for centuries with some maintenance. Why were they replaced?
Were the old knobs non-functional somehow, or were the owners too cheap and lazy to bother with taking things apart for a bit of TLC and preservative paint?
What other parts of the house were done fast, cheap, and/or lazy like a landlord who doesn't give a fuck? What haven't I found yet that they "fixed"?
It’s the faucets and sink fixtures that can jump out at me. I… question some of the Amazon-grade ODDALLCAPS fixtures’ ability to not spring a leak in the long term. Showerheads are more whatever.
And the rest of the plumbing. I'm not saying that homeowners can't plumb properly (many do excellent work), but: Too many times, it's just ugly.
Sometimes it's easy to find: The "soft" parts under the sink are a mess. Flexible pressure lines that are a mile too long, bendy pipes on the drain (this should never happen), traps in series with one another, bizarro-world TPCLALL-branded Amazon-sourced parts that simply do not match regulated norms at all and which haven't seen a UPC® logo ever... but that's simple to rip out and replace.
Sometimes it's harder to find. Drains that go uphill. A sea of CPVC pipes running in every direction, with dead ends, all buried in the basement ceiling. No trap for the bath tub upstairs. Mixed metals. Mixed plastics: PVC is fine, and ABS is fine, but mixing them together is bad (and shows that a trip to the parts store to get The Right Fucking Thing was just too much work, since it wasn't done). Bad or nonexistent venting.
The problems of today are caused by the lazy, quick fixes of yesterday.
the little rubber gaskets in sink drains for garbage disposals are also a cheap upgrade the brings a place up a notch
outlet wall plates
Also make sure your screws in your outlet wall plates are vertical. I've found it's a key tell between mediocre electricians & handymen, and the real pros, and it gives me confidence (perhaps unfounded) that the electrical systems are in good shape.
That's funny - I always align the screws in the wall plates when I (re)install them, but imagined that to be an idiosyncratic bit of fastidiousness. I've never noticed anyone else having done it.
I hate when sellers do this. Replace all the finishes and hardware with the cheapest possible hardware from the store just because it is new. You end up paying for a top dollar house (because now you can argue its worth more than comps that didn't get this treatment) with bottom dollar components.
What would be better is not doing anything and letting the new owner install what makes sense to them, instead of having them pay markup essentially for these placeholder finishes, but obviously we can't have any altruism on this capitalist earth.
What is funny is it is kind of going full circle now with the home decor. All the 70s-80s era finishes boomers are currently gutting and replacing with builders special grey modern blegh are actually becoming popular again among millennials and gen z buyers.
Trump wrote in one of his books that a person selling their car that does not detail it beforehand is a fool.
i find it extremely hard to imagine that Donald Trump would have ever been personally involved in the sale of a vehicle at the level that he'd be making decisions about whether or not it was detailed, but I guess it's sensible generic advice
Or in the actual writing of a book, for that matter.
Visit a used car lot. The cars are all clean and detailed.
Did he also say you should cover everything the tackiest gaudiest faux-gold crap everywhere?
Anyone who takes business advice from Trump is a moron.
If there is one thing Grump does know, it's the value of fools.
> In reality, you'll get much less for your house without cleaning it, because human emotions.
It's trust, because if the previous owners can't even bother cleaning it up, what else might their neglect have done to the house? Maybe I'll need to change the house wiring, verify if any new paint job is hiding mold or infiltration... All that is the cost of uncertainty and uncertainty grows with distrust.
> you'll get much less for your house without cleaning it, because human emotions
It's not because of emotions. It's because it correlates with other neglect that may be less obvious.
A good real estate agent has a rolodex of various contractors that can fix up a house to ready it for sale.
Cleaning the house doesn't retroactively fix the neglect though. It just makes the house look cared for to the lizard brain.
It's not just emotions, it's also a matter of time and uncertainty.
I was in a buying situation where my old lease was expiring soon, I had a second kid on the way, and the last thing I'd have wanted is to buy a place where I'd have contractors milling around for weeks or months to make various repairs. I was willing to pay a hefty premium for a place that's in a move-in condition.
I don't think this extends to "you'll get $10k less if you don't vacuum", but it's a common courtesy on a million-dollar transaction to maybe not leave a mess.
Being rational about this (i.e., buying a dirty or otherwise manageably flawed house) is a great way to save or make money in markets where the majority of the cost is the building.
> because human emotions
A messy, shabby looking home also signals that the previous owners were likely not diligent in taking care of their property.
This simple procedure increases the selling price of everything. Just a fact.
See also why houses are often painted when being staged for selling just so that the new purchaser can paint immediately after with their preferred colour. Wasteful but it works.
People always want to make a place their own with renovations, which means a new bathroom, a new kitchen, a complete lick of paint and the list goes on.
They would prefer to throw out an old suite rather than something that has just been fitted to 'sell the house'. The excuse is provided for them to make it their own.
What they don't want is filth. A spotlessly clean house is preferable to one that has been hastily tarted up with a quick lick of paint. It is respect for the buyer.
People often confuse "irrational" with "rational on inference given incomplete information"
This is the latter.
See also: stereotype accuracy
It's perfectly rational to assume someone who didn't bother to clean the house before selling probably didn't take good care of the house in other, less visible ways.
I spend €125 on an interior decorator and another €500 in furniture and decorations after to make my condo more cozy. And then another €300 for professional photos and drone shots.
The photos looked like those fancy interior magazines. I will never know if it is because of my effort and investment but I’m certain that it attracted a lot of attention. People really want a move-in ready home that looks like the magazines.
> €500 in furniture
I feel like this is 3/4 of a coffee table?
A patchwork of eg new paint is a good signal they're covering something up too
Also you don't need anything fancy when washing them, their surface is just glass.
I agree. Doesn't matter what you sell, you will get a higher price if it is cleaned and tidy when presented to the market - because the kinds of people who pay higher prices are looking for clean and tidy things.
> because the kinds of people who pay higher prices are looking for clean and tidy things.
I'd say it's also "because the kind of people who clean and tidy things also maintain them"
Exactly. "Is it clean and tidy right now" is a decent proxy for "Has this been properly taken care of in the past"
Obviously it's not infallible. But even if the owner only cleaned their stuff now that they are selling it that still tells you they are the type of person to take action where it's beneficial
I think it's more of a negative indicator. It's like turning up to a job interview wearing dirty clothes - unless you're a savant it's probably indicative that you don't give a shit or have some sort of other problems in life. But wearing clean clothes doesn't give you points because it's assumed to be the norm in that setting.
Right. Clean house on the market means almost nothing.
Gross house means almost certainly not maintained.
> "Is it clean and tidy right now" is a decent proxy for "Has this been properly taken care of in the past"
I don't think so, esp at selling time, I definitely expect that the owner has just made it look pristine. But the opposite is definitely true: if you can't even bother making it look clean and tidy when trying to sell, I'm pretty sure you've not taken care of it in the past!
Definitely. On the other side, if you can't even bother to clean it before you sell it, I have no reason to believe you've put any effort in maintaining it.
Cleaning in general is also usually a core part of maintaining something. Dirt and grime lead to wear and tear.
See also "staging":
* https://en.wikipedia.org/wiki/Home_staging
Why is it written like that lmao
Wikipedia is written by various people, but likely someone with interest in a given topic. One or more realtors probably wrote or edited this post.
Actually, the history of edits shows that this is contested territory where people regularly remove what they term as spam links. So, while a disinterested editor might remove a link to a listicle about how to stage your home, they might leave in the breathless tone as harmless. The drive by editors probably feel that they have no more time to rewrite it than we do, given that they watch over many articles, not just this one.
Its been "staged"
I have a 19 year-old, roof mounted, 6.3 kW nominal system in two arrays (east/west facing), 40 deg. north. I've never washed the panels outside of rain and occasional hail storm "scrubbing". Replaced a failed inverter two years ago.
My peak summer output is basically the same as when installed, making 36-38 kWh on a cloudless day. I'm actually impressed my panels haven't really degraded in performance over those 19 years.
That's really impressive and well built solar system, for it to last thta long. It shows how durable quality panels are. I have a 6 month old ~3.7kW system (6 panels in total), planning on installing another 6 very soon. My house is surrounded by trees so it's been a bit of a struggle in the winter.
Panels should do 30 years, easy. Inverters will usually fail after 15y, and with batteries it’s unknown what the current gen will do - 15y, maybe 20? Definitely get LFP.
My latitude plus east/west arrays are a struggle anyway. On the best (presumably cloudless) December day, I got 13.98 kWh. My 12/1/2025 through 1/31/2026 average per day was 10.32 kWh.
What the panels' technology / manufacturer?
SolarWorld, 175 watt, polycrystalline. I don't recall any model number (paper work is filed away somewhere.) ISTR mine were made in Germany. I think at the time my system was installed, there where some 225 watt panels available, but the 175 ones were a better price point per watt.
[edit - added technology]
The SolarWorld company is no more :(
Which means your experience is irreplicable, other companies' solar panels may be crap.
Prices per watt of solar have fallen by so much over 20 years its absurd. You can probably buy the best and/or most costly residential panel on the market and still come well under whatever the median was 20 years ago. Probably well under a few standard deviations below the old median I'm guessing.
Re: the slightly strange shape of the curve. The drop at the beginning could be due to the matching between the panels getting worse. Solar panels in a bank don't like being in different conditions. As a rule of thumb they will all perform at about the same level as the worst in the bank but at the finer levels you could get less straightforward interactions.
The drop off after cleaning could well be because some of the initial boost could come from the water cooling off the panels: solar panels become less efficient at higher temperatures so the drop of after they're all cleaned could be them warming up again after the water has evaporated.
> The drop off after cleaning could well be because some of the initial boost could come from the water cooling off the panels: solar panels become less efficient at higher temperatures so the drop of after they're all cleaned could be them warming up again after the water has evaporated.
This was almost certainly the case. AIUI, that cooling still makes a large difference.
Makes me wonder if it is worth it having a small esp32 or similar control a sprinkler system for the panels. Keep them cool during high ambient temps by spraying a litre of water on each panel every 30m.
An idea I had a while back (when I was considering panels) was running my mains water through the back of each panel (before the mains got to the hose) in a sort of radiator pattern.
People make the same claims about cleaning their air conditioner. Yeah it’s blowing cooler inside: you’ve just chilled the condenser and left some residual evaporative cooling.
Yeah, came here to say this. There are a lot of things that will affect efficiency and how clean your panels are is only one of them. How dirty your panels get is also highly sensitive to both location and installation. All of this gets horribly confounded by string inverters (especially if they're clipping the peak, which they often are).
I easily see 5% increases in efficiency after cleaning (with micro inverters), but also see ~3% increase in output on a hot day from just spraying the panels with water to cool them off, which goes away in 15-20min.
If you're going to clean once a year, do it after the "last" rain of the year before summer peak solar output. If you live somewhere rural with summer thunderstorms, with high angle panels, and without a lot of pollen (or dust storms), you may not need to clean them much at all.
If you're going to climb on a roof, do it safely! A 10' fall can kill or maim you.
Was just watching a video about a guy who has a boat that runs on solar power that he drove all the way from Finland to the Mediterranean in Winter. Obviously in the winter he was charging his batteries using shore power. But since spring he's been running on solar power doing long journeys and maxing out at 5-8 knots. He just cleaned his panels. Lots of salt, dust and sea gull shit. Also a few kids dropped a rock on one of his panels. Cleaning them improved performance by about 10%. Not nothing. But they were really dirty.
https://www.youtube.com/watch?v=FhBBUFuTwR4
It's a bit worrying the author is asking chatgpt about the tingle rather than making sure there's a grounding lug on all the panels and they're all bonded to a grounding rod.
The rudimentary nature of the setup makes me think there isn't something like a single conductor 12awg (or euro equivalent) copper wire that bonds to all panels and a basic $30 rod.
Eh, compared to what though? Compared to speaking to licensed electrician, definitely. But compared to doing a raw web search and trying to put the information in the right order for the application you’re currently working on, I think it’s at worst a wash.
> a wash
Well done on this cleanly-executed pun.
Took four open weight models to land it. And you are giving me way more credit than I am due.
The system in question does not have a transformer so a grounding rod is not required as it is not a separately derived system.
The equipment grounds should be tied together to prevent any difference in potential though.
There are many different ways to connect solar panels to the inverter. Usually the exposed metallic parts will be “grounded” (bonded to the ground / protective earth / equipment grounding conductor / whatever your jurisdiction calls it at the inverter).
But this is an array that looks a bit remote from any structure, and even if the electronics themselves are utterly, perfectly safe, the bonding wire will cause the panel frames to be at the potential of the inverter’s ground, and the soil will be at whatever its local potential is, and this may be different, resulting in a “touch potential”. You can mitigate this with a supplemental ground (or whatever your jurisdiction calls it) closer to the panels. There are fancy ways to do this particularly well to improve safety in the event of a fault.
If you are contacting the actual power wiring of the solar array, something is wrong. If you are feeling capacitive coupled current from the power wiring of the array, then I imagine this means your inverter has crappy filtering, and again the only way you would feel it is if the panel frame isn’t at the same potential as the local soil.
Oh, and if you live somewhere prone to lightning, you probably want to give a possible lightning strike to the panel a better route to a high quality ground than through the bonding wire to your house.
(In fact, in many parts of the world, including IIRC 48 US states, the power utilities may operate their distribution networks with a current carrying wire (combined neutral and ground) that is grounded at multiple points along its route, which will generate substantial leakage current through the ground. The exceptions are IIRC California and Wisconsin, and IIRC those states have their rules to help protect cattle from becoming part of an undesirable circuit while being milked. In CA at least, all the distribution transformers on the poles have at least two bushings on the primary side, and this is why. I believe this is California General Order 95, rule 33 [0].)
[0] https://ia.cpuc.ca.gov/gos/go95/go_95_rule_33.html
You’re allowed to add auxiliary grounds per NEC 250.54, they don’t do anything but you can certainly add them
> Oh, and if you live somewhere prone to lightning, you probably want to give a possible lightning strike to the panel a better route to a high quality ground than through the bonding wire to your house.
That’s what a surge protective device installed in your service entrance is for.
Horses for courses. My system is off grid, so any extra power is just not used, and its designed in a way that a 2-5% change doesn't do anything. That might be a more meaningful change if I were selling power to other folks.
Kind of off topic, but I see a lot of folks proximate to me have built systems to turn panels so they face the sun more closely. I can see the use in that if you don't have much space or if you have a large commercial operation, but this area is very rural.
My array (4kw) which I built myself has 10 400W panels. The panels cost me $1200 because the minimum order is 12 and the supplier suggested buying extras; shipping large panels one at a time isn't cheap. In fact, the shipping for the entire system (about $5000 worth of equipment) was almost $1000.
But my feeling is that for the cost of a moving array that tracks the sun / time of year would have cost quite a lot more and have involved construction that I personally wasn't comfortable with. The conclusion I came to is that it would cost about the same to build a second array, angle it for "summer" (mine is angled to be most efficient in winter), and hook it to the other MPPT on my controller.
That would take up a lot of space, but a) I am 40 acres and b) then I could run a mig welder with impunity during the day...
A lot of these designs are an artifact of a time when the panels themselves would have been far and away the most expensive component in the system. The place I'm in originally had 10 125W panels that probably cost north of $8k when installed, and they were mounted on a rotating, tilt-adjustable post. Also the entire house was wired to run off DC as much as possible, with three different wiring schemes throughout and rare & expensive appliances. It reminded me strongly of RV power schemes, and maintenance was probably a huge headache.
I replaced it all with 9kW worth of panels (about $3k, shipped) on 4 simple 60° ground mounts, normal wiring and appliances. Angle is optimized for early spring / late fall - there's effectively no sun in winter, and the rest of the year I have excess power even with fixed, sub-optimal angles.
The diminished cost of panels alone over the past 20 years has transformed "off-grid" from a pastime for wealthy hippies into a reasonable solution for remote living.
Ah, that makes a lot of sense.
It does no longer pay to be clever with solar panels; they're too cheap. Angle not quite right? Add a couple extra. Summer vs. Winter? Add a couple extra.
> Summer vs winter, add a couple extra
My 6.7kW system produces 2.5 what we need in the summer, and 0.5 of what we need in the winter (even though its output here in New Mexico is relatively constant). Adding a couple extra is going to accomplish nothing in the face of a winter heating system (even with high efficiency heat pumps).
Except in germany where if you install too many you get classed as an energy company and have to pay extra tax. yay.
You don't get "classed as an energy company", you just have to pay taxes on the money you make from selling the energy. This starts at 30 kWp (up to that size, the income is tax free), which is very likely more than what you could put on a private home.
well I mean okay, but it happened to me, and i had to pay a lot to an accountant to do this paperwork and i resent it utterly. I guess it’s unpopular here to be dissatisfied with the insane bullshit tax system in this country.
I didn’t make a profit, it’s not commercial — but apparently getting to almost break even on my energy bills is a “profit”.
Your post sounds like there is some strange rule regarding taxation of solar installations, but it is (or rather was) just treated as any other income from commercial operation.
- If you have any income from commercial operation (selling stuff) you are required to declare that, when doing your taxes.
- When selling electricity you're not so much classified as an energy company, but fall under similar taxation rules as a company. This also means you can get the VAT back, you paid when buying panels, inverters etc.
- Since 2023 solar installations smaller than 30 kWp are completely exempt from this taxation scheme. This means you're not paying any VAT, when buying equipment for your solar installations and don't have to declare the revenue.
- You can get around the 30 kWp limit under some circumstances by having multiple separate installations.
- Parent post is talking about an off-grid installation, which would be exempt anyway, because there is no revenue from selling electricity.
The tax exemption from 2023 was a very welcome move by SPD and the Green party to reduce bureaucracy regarding solar installations and I think the 30 kWp is pretty reasonable
Would be interesting to see, how other countries are handling this.
even for the off grid system not connected to the grid?
Dust can reduce capacity by 40% in the desert.
https://link.springer.com/article/10.1186/s40807-017-0043-y
Washing solar panels is one of the current popular business ideas on social media. It’s an easy pivot for anyone who already has some experience with much harder home repair handiwork involving a ladder.
The reason it’s popular is because most people don’t understand the economics at all. Someone can go door-to-door in a neighborhood offering to clean solar panels and making huge claims about improving efficiency so much that you can’t afford not to do it.
Homeowners who invested $30K in solar panels think of a $300-600 charge as an easy choice to keep their investment producing money.
My parents had someone going around their neighborhood trying to charge $50/panel for cleaning. They didn’t even climb a ladder. They sprayed washing solution from the ground. Most neighbors declined, but you could see the guy spraying down a couple roofs.
Easy way to clear $1000+ per day for knocking on some doors and pointing a hose at a couple rooftops, at least until the public figures out the scam.
I asked a friend with a window cleaning business and they charge about $10 a panel. At that rate I'm tempted to try it but I'm not sure if it's even worth that.
Its an easy value add for a pressure-wash / soft-wash business
Maybe the thing to do is to NOT upgrade existing working panels but rather set up a different/separate entity with completely different accounts and new panels?
And about the washing, I wonder if it would be worth it to automate the process with a spray of water periodically? You can still wash the panels but I suspect it won't be necessary if there isn't too much dust accumulation? Isn't rain supposed to wash away the dust? What am I missing here?
It may also be worth spraying them with water when they are too hot. As they get hotter the efficiency drops a little. It's only a few percent, and usually it happens at the time you need the efficiency the least because it's sunny, but if you can combine cleaning and cooling and get a few extra w out if it, why not.
Solar panels are increasingly being oriented east or west instead of south, as while it reduces overall yield, it maximises power when it's needed the most - during morning and evening peaks.
I don't have numbers, but I suspect it alleviates issues with dust buildup and temperature.
Tracking systems are also becoming more popular. You spend a little more up front but get a lot more usable power.
The most interesting trackers to me, for DIY install in my yard, is a 2-axis tracker. Especially in summer, sunrise and sunset are quite a bit north of east and west, meaning a true south facing fixed set of panels wouldn't even see the sun yet.
Sadly, my investigations a few years back indicated that a suitably strong and robust 2-axis tracker that would withstand our local winds and snow loads is significantly more expensive than just buying more panels and facing some of them east/south/west to accomplish the same thing. Doing this on an existing shed also avoids some local zoning rules vs a dedicated ground mounted system.
I get the impression they are getting less viable because the extra cost and maintenance outweighs just putting more panels down. There are some calculations that suggest even mounting them on angled frames might not be worth the cost, depending on how dirty they get when you just lie them flat on the ground.
(This assumes that you have enough space, but for grid-scale solar this is not the limiting factor. The costs are roughly in order from most to least: the cost of the inverters and grid connection, the cost of installing the panels, the cost of the panels themselves, then the cost of the land to put them on)
I can speak to this somewhat. My panels are on adjustable frames. Typically I switch from flat (summer) to tilted (winter).
As always ymmv and depends somewhat on your location. I'm around 30 degrees from the equator.
During summer, lying flat gets a lot more power. And more importantly the start and end of the generating period is longer. Ie the panels get more sun in the morning and evening thankfully they were tilted.
In winter the sun is more "from one direction" and obviously is lower on the horizon.
Panels are so cheap now you're better off just installing twice as many without tracking.
isn't that more of a storage issue, which a home battery would solve?
A battery would solve it, but it can be cheaper to have additional panels oriented east and west than to add the equivalent battery capacity
Storage is one way to move time of supply to match time of demand. Offsetting the time of supply directly is simpler, although it probably doesn't offer a complete solution.
The upcoming "balcony solar" legislations will allow up to a limit (iirc 1200W in Virginia) of solar to be directly be connected to the electricity outlets of a house to make our electricity costs lower without having to pay for a battery from what I understand.
Yes, I meant I can get on board with automatically (periodically or based on some trigger or sensor) spraying the panels with water but I was hoping it isn't necessary to use Windex® or even dish soap on the panels themselves.
> You can still wash the panels but I suspect it won't be necessary if there isn't too much dust accumulation? Isn't rain supposed to wash away the dust? What am I missing here?
In places where solar panels are used the most, like the Southwest US, there isn't much rain to speak of. Panels get a lot of dust accumulation from Feb-Nov typically, just when they're needed the most.
The author had ground level access. In that case, A microfiber covered sponge on a pole with a 5 gallon bucket of soapy water is probably the easiest thing. Especially if you do it annually, the dust wouldn’t be completely caked on requiring scraping and excessive elbow grease.
I do a similar procedure for my house windows. I use a squeegee on those but probably not necessary for panels.
Some places don't get much rain (and these are the places that tend to get even more dust - e.g. deserts).
Look at any outside surface in a rainy climate.
The dirt may not be piling up, but it's far from clean.
In the southeast states in the US, we experience "the pollening" each Spring, which can leave 1/8" or more of thick crusted pollen on solar panels. I wash ours at least monthly March through May. They're at least 15-20% more efficient, if not more, without the pollen crusted on them.
I clean my solar panels, 7kwh, every monmth or two.
When I check on the VRM portal it makes a difference, and since I am so dependent on them all year round, I have no problem giving them some attention from time to time. Ten mins well spent.
I am curious how much of a difference it makes.
I have 4kw of panels and 15kwh of storage. I only get down to about 80% most nights (I heat with wood and propane).
But my system will charge completely in about 2 hours of full sun. If it took 3 hours it wouldn't make a difference. So I generally don't clean them (well, the rain and snow do that work).
I do remove snow, because that has a very noticeable impact.
Is the difference that you are pushing back to a grid (I am not), so the power all gets used regardless of you being the one to use it?
I'm off grid, no mains power, and have 8x48v lithium Fogstar batteries in an external rack, since my cabin is small.
On December 21, due to trees, my panels get around 2 hours of full sun, if the universe smiles on me.
I use around 5-6kwh per day, if I use my computer, which I need for work.
This will be the first year with the fogstar batteries, previously had 1x48v generic lithium battery, but last year I used the generator most days from around end of november until March e.g. December consumption was 153kwh, solar generated 62kWh, and generator made up the rest.
This year, thanks to having more storage, we'll be better able to take advantage of sunny days and capture more power. I also have a freezer and washing machine this year :-) Ask me in March how it went.
All of my panels are easy to access, none on a roof, so the effort is minimal and has non-zero power benefits in my experience.
I should add that I am surrounded by trees and the panels accumulate a green tinge quite quickly, plus bird shit.
> I also have a freezer and washing machine this year
You need a heat pipe between your freezer/fridge and outside. Then it will “function” when it’s colder outside than in your fridge and otherwise sit idle(ish). Sure you’re bringing “cold” into your big warm box (home), you have wood to overcome that. All theory, but it makes sense in my mind!
(Though in most places, it rarely gets colder outside than in your freezer)
> I clean my solar panels, 7kwh, every monmth or two.
This honestly sounds like a non-trivial strike against installing solar panels, especially if they’re installed on tall roofs.
I definitely wouldn’t want to have to clean them that often, or pay to have them cleaned that often.
If you’re spending only 10 minutes on them, then maybe you don’t have that many, and they’re not up high.
Roof-mounted solar panels are a necessity in urban situations but they are a maintenance nightmare compared to a ground-mounted array. That has to be accepted as "the cost of doing solar" when there is no other alternative.
I never cleaned mine. Rain does enough. It's still plenty valuable without minmaxing them.
Mine are not on a roof.
On tall roofs there tends to not be much dust.
Our peak daily export energy jumped by about 35%-40% when we had our panels cleaned for the first time in 8 years. They _look_ much cleaner, and the measured export shows it.
If export energy is 10% of your total output, and it jumped 35% then you got a ~3.5 - 4% gain in total output, not far from the author's experience.
Of course, you can math that any way you like to make the numbers bigger or smaller, depending on whether you're representing the buyer or the seller of the system.
It's not 10%, it's much more than that. I'm obviously comparing the peak values, which tend to be days when we don't consume much, which might mean a background 100W vs a couple of kW peak generation. I can dig deeper into the per hour generation and it's similar.
> This is the yin and yang of market-distorting incentives. Today's incentive to install solar becomes tomorrow's disincentive to upgrading it.
Facing this as well. We've got our 5.2kW system in a pile in our yard as the house is being enlarged, new roof going on, etc. We're switching from a gas furnace to a heat pump system, and will also be installing a hot tub. I'm sure our annual power bill will double from say $1k to $2k, but it doesn't make sense to enlarge our system.
I'm 8 years into a 20 year net metering scheme (NEM2.0 in CA), and any changes I make will kick me off the plan. In theory I am allowed to add up to 10% or 1kW, but in practice my solar company keeps telling me it's not worthwhile. I think the paperwork and administrative burden of even adding the amount I'm "allowed" to add just means it's not cost-effective.
Whether or not the utility actually would notice that I'm mysteriously getting 1kW additional generation (if no paperwork was filed) is another story.
> If I increase the power output of the system then the additional capacity will not be eligible for the feed-in tariff and will revert to present-day prevailing tariff which is about 4x worse before you even consider that I currently get to use electricity and still get paid for generating it.
> This is the yin and yang of market-distorting incentives. Today's incentive to install solar becomes tomorrow's disincentive to upgrading it.
I am not sure what author is trying to hint. But solar does not need artificial subsidies, and can pay for itself!
There are no subsidies in UK! Homeowners get so much money, because of all that sunshine and wind energy, their house generates! UK goverment just run out of money, when energy got expensive!
UK goverment needs to step up, to replace gaz with renewables!
You can not expect homeowners to sell energy bellow market price!
> solar does not need artificial subsidies, and can pay for itself
That's true now, but wasn't true when those panels were installed. There were subsidies available to get the market kick-started.
They consist of an extra payment for every kwh you generate on top of the payment for delivering the power to the grid. The amount varied depending on when you signed up to the scheme, but at certain points it was as much as 50p/kwh (+ inflation, so more than that now).
> I am not sure what author is trying to hint. But solar does not need artificial subsidies, and can pay for itself!
At grid scale, yes.
For the house, not so much.
The feed in tariff was at one point 41 pence per kwhr which is probably £10 a day in summer.
but at 12p a kwhr it drops to £3.6
However, 10kwp of panels is ~£1800, but the micro inverters needed to drive them are >£3k (as its outside you can probably use two larger inverters.) Then mounting system is probably a good 800 quid too.
Solar gets lots of subsidies in the UK. Homeowners who installed it 10 years ago get a ridiculous payment for generating excess, even if the grid doesn't use it.
> I am not sure what author is trying to hint. But solar does not need artificial subsidies, and can pay for itself!
I think he is describing a subside that some governments gave years ago: you installed for example 5K, and get paid for whatever they generate at 300% market price, for a long time (25 years?). Today you find out that upgrading panels would made perfect financial sense, if you were selling at 100% and are going to sell electricity at 100% (you will be doubling the output for a tenth of the inversion 15 years ago), but as the subsides of 300% no longer exist, you will be actually losing money by upgrading.
That's not true. You can upgrade to the same capacity on the previous feed-in tariff and keep what you had. It makes sense to upgrade as you can then fill the extra space with additional panels (which will not be on the old tariff, but can be a separate system).
when it first started it was basically 450GBP/MWh (In 2010 GBP). and that was paid for every kWh generated (whether exported or not). And the PPA lasts for 20-25 years.
There’s this viral video on X of a guy at an Alex Hormozi talk saying he makes money cleaning solar panels… and it’ll probably turn into a whole market. If he’s getting 2% to 5% gains, I can already see marketing blowing that way out of proportion
Appreciate the attempts to quantify it. I haven't tried to quantify washing, but I do look at mine regularly. I doubt anything accumulates that rain doesn't handle well enough.
Messing around with ground panels is lower risk and safer than roof panels where tool extenders and ladders start to become involved. If you have roof panels, you are the biggest danger to your panels (and yourself.) Don't try to clean them, spray them, knock snow off of them. I was told this multiple times by my installer. :)
As another anecdata-point, when we did this for a now already fairly old roof installation of about 15kWp, it was more than “just about worthwhile”, since the panel area is contiguous: cost seemed to scale up less quickly than the wattage/theoretical maximum output, and the cleaning guy (solo company, IIRC) even told us it wasn’t necessary to do this every year (we hadn’t had it done even once the first decade+ of the installation’s lifetime).
So, at least in our case, definitely worth it.
Interesting; what was on the panels? What was the ROI on paying the guy?
Now I want solar panels merely so I have a reason to not have to clean my roof
Still the same leaves in the gutter, sadly, once they blow past the panels.
In many countries it is actually illegal to use tall ladder etc. owners would have to erect a scaffolding to make access for work people to clean it safely.
There are definitely some wacky nanny state rules out there… but I’m a little skeptical of “In many countries it is actually illegal to use tall ladder”
Probably the GP meant to hire people and order them to use a tall ladder. I don't think there's any country where it's illegal for you to use one outside of some kind of contract.
Tradespeople are typically independent contractors. You hire them to do a task, and they use their own judgement on which tools to use. You don't order them to use a tall ladder...
And hopefully these independent contractors are insured. It may well be insurance requirements that limit the use of ladders.
The regulations that tradespeople must obey and how they are contracted varies from one country to another.
It would not surprise me if this was a law in Germany, for example.
Stuff like this is why America continues to mog the rest of the world economically.
So if it's a 2-5% increase, barely break even, it more than breaks even during an extended power failure if you live somewhere this is likely. There are a lot of things I choose to do to avoid future timelines where 'sus appliances break at the worst possible moment. This would be along the same lines to me. Your mindset may vary YMMV.
But if cash is tight, yeah, not so much.
Nobody can answer this. It simple depends on each setup. Some panels will get incredibly dirty quick like those in the south west where there may be a lack of rain and lots of dust but in other regions you may never need to.
There are at least a couple of outfits claiming a nano coating or a nano glass surface for solar panels that are so smooth as to not collect dusts. Their other claim is greatly improved angular photon capture since the panel is just that flat. The two companies I've seen claim ~20% improvement - and less maintenance.
20% seems high enough that if it was really _that_ effective, the companies making the panels would be tripping over themselves to buy this coating to apply it to the panels right in their factories. (And charge a premium for it.)
My solar panels are leaning in stacks in my yard, as our house is currently being removed with a new roof, etc. I'm planning on cleaning them while they're "loose", but I wonder if it also makes sense to apply a(n automotve-style) ceramic coating to them.
Given the angle of a panel should match its latitude and average sun angle, the panels might generate noticeably more by being pitched steeper at over 30 degrees. Eyeballing this, it appears closer to 25 degrees right now which doesn't even make sense for the summer sun in the UK. I could be wrong as it also appears these are on a slope!
Of course washing them makes sense, physics-wise. As others have pointed out, you are almost certainly seeing a rise due to cooling off the panels (this would not make economic sense to do all of the time). Temperature has a pretty dramatic effect on solar panel output. Cooling a panel can boost production by 10% or more. Do not polish them. Solar panels are designed to be anti-reflective. You don't want a shiny surface.
But, the real factor in all of this is how valuable the time required to clean the panel is.
It totally depends on your area. In the PNW I get sap and conifer tree pollen all over my panels and have to wash them at least twice a year.
Should we include this is the cost?
I know that dust on the panels is one of the reasons that one of the Mars rovers eventually croaked.
On Mars, the wind storms and dust devils are so fearsome that some of the robots there could rely on dust being blown clean off all the solar panels on a regular basis. Spirit and Opportunity benefited the most from these effects.
InSight was stationary and not so fortunate. But, the ground team got quite creative with its robotic arm to try and manipulate the sand that had accumulated on the solar panel, and gained a little bit more power.
https://en.wikipedia.org/wiki/InSight#Surface_operations
https://en.wikipedia.org/wiki/Martian_regolith
I haven't noticed too much of a power increase in my backyard solar farm after cleaning, but I do notice a very significant increase by weeding the surrounding stuff. Even a pretty small amount of shade will very significantly reduce your yield, like seriously 20-30%.
Oh, also, I've noticed that at least with my panels, bird poop seems to be particularly bad. The dust that accrues doesn't seem to do much, but even a relatively small bit of bird poop will be almost as bad as weeds. Fortunately it's not terribly difficult to clean once it's dried.
Yeah, the one tree branch that hits my array until 10a prevents it from charging at all even though it only obscures 1/4 of one panel in the 10-panel set.
But I like the branch and have plenty of full sun, so I haven't cut it.
I imagine rain will clean them. In most places it rains every so often.
Rain usually just cakes the dirt. Unless it's a downpour, it doesn't move with enough velocity or volume to remove the dirt. So the dirt just gets damp, maybe moves a few cm with gravity, then dries as a mud cake.
See this all the time in Phoenix metro: A light rain just pulls down all the dust in the air and deposits it on the car. It has to be fairly sustained to wash away the initial dust collection, and even then you can still see dust on the paint.
my experience is that unless you get some really torrential rain, it's not enough to clean the sand/dust/grime
Can confirm, my car doesn’t get cleaner unless there’s a downpour
Definitely wash the panels.
However if you are using a string inverter you will want to wash all the ones on the same string in one go if you can, you don't really want them generating different voltage or you will miss out on a lot of power.
I'm surprised that the outcome was not much greater improvement. I'm glad though it removed one of my concerns about solar. I'm glad cleaning maintenance really is not really needed.
If you feel "a tingle" when touching solar panels, that means there's a ground fault, a wiring short, or a missing ground wire. This is incredibly dangerous as solar arrays carry hundreds of volts.
Question for people here: my local power company charges a fee if solar is attached to the grid and is high enough to make installing residential solar impractical.
I'm thinking the best thing to do would be put a large battery in between the grid and my home and selectively recharge the battery with the solar. I believe that setup circumvents the fee since the only thing using energy is the battery, as though it were an off grid setup. I might consider not putting the entire home behind the battery but just the largest energy hogs, like the HVAC or others.
Does this make sense, are there existing setups like this and what are thoughts about something like this?
Thanks
Without trying to answer your "I believe the setup circumvents the fee" implied question, which you should find an actual answer to...
See reddit's r/solarDIY. There are a lot of setups like this, either for full house power or partial. I have a relatively big server in my basemeent that I power this way, for example, with a battery system that acts as both UPS and a "charge the battery from solar and run off inverter when possible". Something like an off-grid EG4 is popular among the reddit crew as a way to manage this; the device tries to run locally but accepts a shore power feed from the grid so if you need it you draw grid power. No grid tie involved.
> I believe that setup circumvents the fee since the only thing using energy is the battery, as though it were an off grid setup.
Entirely based on your jurisdiction, but that kind of zero-export requires the same permits and connection fee as a full net metering in mine. You can't end run the process by just being sneaky, electrical work needs permits and they'll either make you take it out (!!) or bring it into full compliance.
As an example, my utility is one of those ones that requires a separate manual disconnect, even though the vast majority of all-in-one inverters have a built in disconnect. It doesn't make any sense and it's at least two grand in permit + equipment, but that's the rule.
Having just put a battery into my existing system. For the power company I use the answer is no to your question. Many power companies charge that fee depending on the size of panels. Now if you do not hook to their system they do not care (off grid). But if you plug into it then they care and charge for the privilege.
Now you could pull particular items out of their grid. Just need the wires and panels to make sense. They would not care about that either. It is only if the panels are plugged into the grid they start to care. Downside is sometimes waiting for that battery to have enough juice to work. It goes faster than you think and some battery systems are decently expensive just by themselves, on top of the panels/inverters/controllers/install.
Ask a lawyer about the law.
Why would I ask a lawyer for advice about whole home battery solar setups with a grid backup?
Because often the law cares about intent, not technicalities. Technically you could argue that this is a "whole home battery solar setups with a grid backup", but clearly the intent is as a workaround.
I'm not saying this is bad. I love a good workaround for onerous laws & fees, but random Internet commenters aren't the best at determining what workaround will or will not pass muster if a judge gets involved.
Like someone said in another recent thread: "U.S. law though is highly non-autistic and what you were trying to do is just as important as what you superficially did." https://news.ycombinator.com/item?id=49064242
Because you're asking legal question about what the law allows, not a technical question about how to exchange voltage and current.
That depends on what options are available to you for residential solar installation. Installing solar panels + micro-inverters is very cheap in cost of parts, but possibly expensive in labor. It will easily pay off your grid interconnect fee every month once you hit break-even from operating for a few years. Financing vs cash, cost of installation, tax credits, are the biggest factors in how quickly it becomes profitable. If you are extremely handy you can DIY most of it as a homeowner (depending on local/state laws) which cuts costs significantly.
You can do a whole home backup + solar panel input (aka ESS+PV) but it's much more expensive in parts and installation and is more complex. If you don't add grid interconnect it can be much cheaper as you can use "off-grid" parts (grid interconnect requires more expensive parts certified for certain standards).
But some jurisdictions may not allow cheaper "off-grid" parts/systems to be connected to the grid, even downstream. So an alternative would be to install a transfer switch, where you manually switch from the grid to off-grid. But then you literally have to choose whether you use the ESS+PV or the grid at any given time and manually throw a switch (you can't use grid to charge your system). And yes you can set this up for only specific circuits/appliances. Again it depends on your state and local laws.
AI can do most of the research for you. Keep a Git repo and add documentation and details to it over time, and you can build up an analysis of what works for you based on all available options, price comparisons, energy requirements, and local/state laws. It is unfortunately quite complicated because there are many options but not all will apply to your location. And before you do any of this, do a solar site survey to see if you can even reliably generate enough power from the sun!