At the end of March I was seized by a sudden yearning to clean my solar panels. They were installed 10 years ago and have never been cleaned. The are on a garage roof, so quite accessible, and on the evening of 31st March I took my power washer and set to.

My west facing garage roof with 3kW Solar

Power washer at the ready

IMPORTANT WARNING: I was pretty cautious about power washer setting and used it on a low setting only. I didn’t want to cause issues with my solar system. Companies that offer panel cleaning generally only use low pressure systems, so we recommend you take advice from a professional cleaning company before doing this at home.

I have a couple of quite satisfying snaps showing the before and after. At least I think I got a better shine on the after shot.

Before cleaning

After Cleaning

The big question of course is “Did it make any difference?” This is a bit hard to assess. Generation varies daily based on weather conditions, and late March, the rate of change in day length every 24 hours is at a maximum.

That said, I am an engineer so of course I took a look at the data consisting of some historic weather data and my historic generation levels.

March and April Weather and Solar Generation Data

March data was before I cleaned the panels. April data was after the cleaning.

When I look at the data above, I think I can see some trends. For example 1st April was pretty sunny as was 29th March, and 1st April got a bit better generation. Not definitive, but until I can do some better testing, I think I shall be keeping my panels cleaner to get the maximum generation.