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Should you wash your solar panels?

incoherency.co.uk

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Re: Should you wash your solar panels?

#251

Post by dredmorbius »

Aurornis wrote: post #78

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…

Many years ago (and possibly still today) there were firms offering refrigerator-cleaning services. Brushing off the condenser (external) coils.

Yes, that may save you a bit of energy. No, not that much, and overall the financial savings are a small fraction of the service's charge.

A friend worked in energy conservation at the time and actually studied the impact of cleaning coils on refrigerators as part of a recycling programme (so: measuring pre- and post-cleaning power consumption on units which had been in use, most for quite some time). The net results, over hundreds (if not more) units: to little difference to detect statistically.

If you're doing the work yourself or don't have to pay for it: possibly worthwhile for peace of mind if nothing else. Paying someone else? No.

I suspect a similar situation for solar panels.

Re: Should you wash your solar panels?

#252

Post by john01dav »

benj111 wrote: post #239
john01dav wrote: post #103

Earlier quoted context omitted.

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.

For the same reason, get a car with dents, or light obviously bubbling.

I did exactly that! 2000 Toyota with dents, a little surface rust, and a good engine and transmission

Re: Should you wash your solar panels?

#253

Post by cestith »

kaelwd wrote: post #45
cestith wrote: post #21

Earlier quoted context omitted.

Tracking systems are also becoming more popular. You spend a little more up front but get a lot more usable power.

Panels are so cheap now you're better off just installing twice as many without tracking.

If you can do that within your space constraints you’re probably right.

Re: Should you wash your solar panels?

#254

Post by ssl-3 »

dlubarov wrote: post #247
ssl-3 wrote: post #136

Earlier quoted context omitted.

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 s…

I think it's safe to say you're in the minority. Empirically, "fast and cheap" cosmetic upgrades like repainting usually more than pay for themselves. > I'd rather the outlet covers be original and clean than the new, usually oversized covers (with a slight color mismatch) I often find. Any task can be screwed up if someone is careless enough, but this is extremely easy to get right. If a standard cover plate fit bef…

That's the problem: Any task can indeed be screwed up. It can be worse than it was before.

A new, not-oversize cover plate that actually-matches in color is fine. As you suggest, it is trivial to get that right.

But people screw it up anyway, and when they do so it represents a distinct lack of attention to detail. If I find that along the presence of other new electrical stuff, like outlets with USB jacks, smart home dimmer switches, and can lights with fixed LED elements, then... man. They obviously couldn't even get the outlet covers right. What else did they screw up, that I can't see?

Old caulk that was skillfully applied and remains in good shape isn't a problem; it is not broken and does not need fixing. New caulk that is well-done isn't necessarily an issue at all. Both communicate that a base level of positive care for the quality of the home was present.

But when it's sloppy, it's a clear indicator that they just didn't care much at all during the process. There's direct evidence that they were unwilling to put the effort into making a smooth bead of caulk instead of a messy one. They didn't care about that part of this small job, and by extension they probably didn't care about what they were covering up (whether it was good, bad, or indifferent).

Anyway, maybe the lazy fixes work for enough buyers that it does increase the sale price, and that's good for a seller.

It doesn't work for me, though. The presence of these kinds of things brings me more questions than it does answers.

---

The answer that maximizes the price by satisfying all potential buyers is to do careful and correct fixes. If the quick fix makes some money, then a good fix makes even more money. Take the time to get it right.

Re: Should you wash your solar panels?

#255

Post by trimethylpurine »

hgomersall wrote: post #74
trimethylpurine wrote: post #49

Earlier quoted context omitted.

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.

I'd just measure total output and don't bother looking at export output. More variables and conversions in the experiment will tend to reduce the accuracy of the results.

Re: Should you wash your solar panels?

#256

Post by manmal »

sgt wrote: post #238
manmal wrote: post #173

Earlier quoted context omitted.

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.

I've seen cheaper Chinese panels fail after less than 10 though.

Yes there was a generation with plastic back which fell apart. Everybody uses double sided glass now. Should be good.

Re: Should you wash your solar panels?

#257

Post by aetherspawn »

quickthrowman wrote: post #219
aetherspawn wrote: post #212

Earlier quoted context omitted.

I’m an electrical engineer. I just want to explain the hazard with panels. They are DC, and the voltage is usually very high, between 300V and 600V. At this voltage you will get a burn, like touching a hot kettle, but because it is DC you will be able to easily “untouch” it. Yes, the panel frames should all be grounded to each other, and also to Earth in one spot along the chain, as this makes it more difficult to be…

I was just pointing out that a solar installation with only an inverter and no transformer does not need a separate ground since it’s not a separately derived system. An auxiliary/supplementary ground rod is allowed by the NEC (250.54) but it is not required.

Well, this is US code which is fairly lax and has a ludicrously low voltage grid, but in virtually every other country it is required

Re: Should you wash your solar panels?

#258

Post by Breza »

lelanthran wrote: post #170
rcxdude wrote: post #28

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 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…

Growing up inMichigan in the nineties, solar water heaters were surprisingly common. Your comment makes me wonder how hard it would be to pipe water through the PV panels en route to the actual water heater.

Re: Should you wash your solar panels?

#259

Post by msdz »

1123581321 wrote: post #75
msdz wrote: post #11

Earlier quoted context omitted.

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 th…

Interesting; what was on the panels? What was the ROI on paying the guy?

Unfortunately I don’t recall anymore, since this took place at my father’s PV installation.

I’ll try to post an update when/if I get exact numbers, though!

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