Rain and cleaning solar panels


Well-known Member
We've had solar panels on our house which was fitted back in 2015. The panels are split 2KW SE and 2KW SW facing I have wondered about if we should clean the panels to see if improves the generation. Had an interesting observation today, after the heavyish rain we had this morning I noticed the generation was hitting 2.4KW, versus sub 2KW a few days ago at the same time in much better weather.

Tomorrow we'll have more sun so I can see if the rain really has improved the performance of the panels.

Any other forum members with more experience of if there is an actual need to clean solar PV panels, or just leave it to the rain?



Active Member
I have the same split system installed in 2013. After heavy rain generation is always better but this is not down to the panels having the surface dust washed off. Its to do with the UV being increased due to moisture in the air or something along those lines. The navitron forum is full of members who will explain better.
Clean panels do increase efficiency but unless you can get to your panels easy you would never recoupe the costs of having them cleaned by someone who is willing to climb on your roof


Well-known Member
I was wondering the same when we had 10 weeks with no rain. There was a slight drop in output which bounced back after some heavy rain. Ours have never been manually cleaned in 10 years.

But no way would increased output have covered the cost of a clean (@ 51p per kWH on a 4kW system).

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