We have had solar panels for a few years and they are all working fine. But could cleaning solar panels make them work better?
Doing some research on solar panel cleaning there seems to be 2 opposing views (as always).
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One view is that glass is ‘self-cleaning’. As rain water washes the panels regularly you might only be losing a few % of the yearly generation. They go onto say, if you do clean them, within a few days they will be dirty again anyway. The other side (mainly solar panel cleaning companies!) talk about losing between 5%-30% of the yearly generation from dirt. Even a thin film of grime on the panels reduces the amount of light which gets through to the panels. I saw one site comparing the solar panels to the windscreen in your car. You can’t go long without cleaning that and the rain doesn’t do much to clean it. I’m not too convinced by that argument, but I do know what state our windows get in if left unwashed.
Is it worth it?
Well 5% of my yearly FIT payments (i.e. the money we get for the electricity we generate) is about £100. Although people getting solar panels more recently will be getting much less. The savings could still be more than £700 over the 20 years (at today’s prices). So even a small increase in efficiency will be worth looking into.
All the solar cleaning websites I looked at talked about using ‘pure’ water instead of rainwater or tap water. Looking into this a bit more they say that pure water is H20. Whereas both rainwater and tap water have minerals, pollution, chlorine and all sorts of other things in it. If you have ever cleaned your windows with water and not wiped the water off afterwards what happens? It leaves streaks all down the window. Once the minerals are on the solar panels they attract more and that’s how they get so dirty. Cleaning with ‘pure’ water doesn’t leave any mineral deposits so they stay cleaner for longer (at least that’s the theory).
What are the options?
I asked a solar panel cleaning company to quote me to clean our panels. They wanted £75 for an annual clean or £120 for 2 cleans a year. One in spring and one in late summer.
I found a few home solar panel cleaning kits with everything you need to clean your solar panels. They were £300+.
Looking at whats contained in the solar panel cleaning kit they are normally made up of the following:
- Solar panel friendly brush
- Extending pole to reach all the way up to the roof from the ground
- Water purifier and pump. The pump can take in rainwater or connect to an outside tap. It filters and removes all the minerals and gives out ‘pure’ water.
It makes a lot of sense for window or solar cleaning companies to invest in all this. But what are the options for the frugal solar panel homeowner?
Well there is another option, a DIY approach.
You have to buy a few bits but they come in useful for other jobs as well.
You need the following:
- An extendable pole (with water tube inside). Check how tall the top of the solar panels are. Buy the appropriate pole and a solar brush. Make sure the brush fits the end of the pole and has attachments for the water tube. (Around £115)
- A Water Pump. *I bought a submersible pump. I can use it for this or to pump water from a water butt (around £60).
- Pure water. This is my best find so far. Instead of spending lots of money on a water filter go down to your local tropical fish shop. They can give you a barrel of 25L for less than £5.
With the above I had all the equipment I needed to clean my panels without climbing up onto the roof. It cost me around £180 for the lot, which was a significant saving on what I could have spent.
It was really quick to do. A few tips though;
- Make sure all the power is off on the panels and inverters before cleaning the panels.
- Do it in the evening after the sun has gone down. So the panels aren’t hot, but its still light enough to see.
- Make sure you adjust the angle of the brush so its easy to clean.
- Test the water through the brush before starting to clean the panels.
Have they made a difference? Well I haven’t really noticed much difference yet, I have seen bird poo on it since though. I’ll keep a close look at it and will clean them every couple of months now I have the kit.
Should you get your panels cleaned professionally, do it yourself or not bother? I certainly wouldn’t pay £75 a year to get them cleaned over 20 years. I’ll hold judgment on the whether is is best to do the DIY version or leave alone.