Should you wash your solar panels? • Hacker News Board

Re: Should you wash your solar panels?

#21

Post by cestith » Mon, Jul 27, 2026, 2:13 PM UTC

Tade0 wrote: post #16

rjmunro wrote: post #8

Earlier quoted context omitted.

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.

Re: Should you wash your solar panels?

#22

Post by z2 » Mon, Jul 27, 2026, 2:15 PM UTC

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!

Re: Should you wash your solar panels?

#23

Post by throw0101d » Mon, Jul 27, 2026, 2:16 PM UTC

engineer_22 wrote: post #20

wodenokoto wrote: post #6

> 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 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.

Re: Should you wash your solar panels?

#24

Post by ape4 » Mon, Jul 27, 2026, 2:17 PM UTC

I imagine rain will clean them. In most places it rains every so often.

Re: Should you wash your solar panels?

#25

Post by namdnay » Mon, Jul 27, 2026, 2:17 PM UTC

engineer_22 wrote: post #20

wodenokoto wrote: post #6

> 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 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"

Re: Should you wash your solar panels?

#26

Post by namdnay » Mon, Jul 27, 2026, 2:18 PM UTC

ape4 wrote: post #24

I imagine rain will clean them. In most places it rains every so often.

my experience is that unless you get some really torrential rain, it's not enough to clean the sand/dust/grime

Re: Should you wash your solar panels?

#27

Post by varispeed » Mon, Jul 27, 2026, 2:18 PM UTC

1123581321 wrote: post #3

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, s…

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.

Re: Should you wash your solar panels?

#28

Post by rcxdude » Mon, Jul 27, 2026, 2:19 PM UTC

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.

Re: Should you wash your solar panels?

#29

Post by collabs » Mon, Jul 27, 2026, 2:19 PM UTC

sluongng wrote: post #17

Tade0 wrote: post #16

Earlier quoted context omitted.

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.

isn't that more of a storage issue, which a home battery would solve?

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.

Re: Should you wash your solar panels?

#30

Post by bradfa » Mon, Jul 27, 2026, 2:20 PM UTC

cestith wrote: post #21

Tade0 wrote: post #16

Earlier quoted context omitted.

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.