So they look good and the potential buyer sees something that looks to be in good condition and working well.

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.

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.

https://www.youtube.com/watch?v=FhBBUFuTwR4

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.

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.

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...

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?

> 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!

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.

And I've seen cases where it made a 30% impact. In other locations, it is a non-issue, but vegetation was a hassle.

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. :)

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.

But if cash is tight, yeah, not so much.

But, the real factor in all of this is how valuable the time required to clean the panel is.

https://link.springer.com/article/10.1186/s40807-017-0043-y

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.

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.

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 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