DIY Solar Panel Cleaning

We have had solar panels for a few years now and they are all working fine. But are they working as well as they could? Doing some research on solar panel cleaning there seems to be 2 opposing views (as always). One saying that the glass is ‘self-cleaning’, the rain washes them regularly (at least in the UK) and even so you might only be losing a few % of the yearly generation. They go onto say that even 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 and that having even a thin film of dirt and grime on the panels will reduce the amount of light which gets through to the panels. I saw one site (here) comparing the solar panels to the windscreen in your car, you can’t go long without cleaning that and the rain doesn’t do too much to it either.  I’m not too convinced by that argument but I do know what state our windows get in if left unwashed for a while.

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 and 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.

What’s involved?

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 just H20 whereas both rainwater and tap water have lots of minerals and pollution and chlorine and all sorts of other things in it. If you have ever cleaned your windows with water and not gone over it afterwards to get rid of all the water 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 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 looked around and 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, which takes in rainwater or a connection to an outside tap and filters it 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:

  1. An extendable pole (with water tube inside) – Check how tall the top of the solar panels are and buy the appropriate pole and a solar Brush – that fits on the end of the pole and has attachments for the water tube (around £115)
  2. A Water Pump – I bought a submersible pump (this one here) so I can use it for this or to pump water from a water butt (around £60). 
  3. Water – and this is my best find so far, instead of spending lots of money on a filter and then have to spend money on the filter material etc you can go down to your local tropical fish shop and they can give you a barrel of 25l for less than £5.
So with the above I had all the equipment I needed to clean my panels without climbing up onto the roof and 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.

  1. Make sure all the power is off on the panels and inverters before cleaning the panels.
  2. Do it in the evening after the sun has gone from the panels (so they aren’t hot) but its still light enough to see.
  3. Make sure you adjust the angle of the brush so its easy to clean.
  4. 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. But I will keep a close look at it, I 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.

Watch out for my update on this next year and what else I use the water butt pump for.

This was a guest post from Mr ETL.

Disclaimer – an affiliate link was used in this post.

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