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> 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.
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.
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 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.
Actually in some places panels devalue a house because some people consider them an eyesore
Also you don't need anything fancy when washing them, their surface is just glass.
A patchwork of eg new paint is a good signal they're covering something up too
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.
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.
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.
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.
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...
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?
> 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!
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.
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.
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.
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. :)
> 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.
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.
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.
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!
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.
I have worked in the solar industry, and "soiling" is highly dependent on soil, weather, proximity to roads, etc.
And I've seen cases where it made a 30% impact. In other locations, it is a non-issue, but vegetation was a hassle.
Dust can reduce capacity by 40% in the desert.
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.
It depends.
In my mom's part of SoCal, it's extremely dusty. Without bi-annual cleaning a solar panel's output will drop by over 25%.
On the other hand, where my brother lives up in Norcal, an annual cleaning is overkill.
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.
Last summer, I washed the single 220W module on the top of my campervan. It definitely improved the yield, but I suspect a vehicle can pick up a lot more dirt than a stationary install.
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.
Are people really not aware that you have to wash your solar panels every few months? Your installer should have told you that much.
I know that dust on the panels is one of the reasons that one of the Mars rovers eventually croaked.
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.
I imagine rain will clean them. In most places it rains every so often.
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 lose about 25% if I do not clean during bushfire season
it's simply common sense. of course cleaning them would make a difference....duh
Talk about "overthinking"...nerds!
Should we include this is the cost?
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