It makes sense - sitting out there in the rain and wind and weather, solar panels get dirty. Because the turn light into electrons, it would make sense that the cleaner they are, the better they perform.
nice clean, shiny panels
With SEGmeter in place, counting the output from my small solar system, the sun at it's Zenith - 12 midday, a clear sky, bucket of water, ladder, squeegee and camera I took to the tin. To clean my system.
After their first six months on the roof, I was surprised by how much gunk had built up on my panels. There were many splotches, patches of bird poo and much and general dirt and fustyness, surely this isn't helping electron output?
When cleaning your panels, use soap and water. In this case I picked my favorite dishwashing liquid. It's mild and gentle to the solar and won't leave you with the dispan hands. I used a 30cm window squeegee to wipe away the soapy water and make it all nice. The total time taken was about 10 minutes for my 6 panel array.
water on, water off.
So what's the rub? It's hard to tell from straight after the clean up. The panels are certainly clean, it it definitely appears there was a slight increase in output - plus one of the highest outputs this winter from the freshly cleaned panels. This higher output seemed to hold well through the day, until the clouds came.
after the rub, more electons!
So if you want to keep your solar system in tip top shape, get up and wash the cells. You may even get more electrons!
Interestingly, in Australia, solar installers aren't allowed to tell their customers about cleaning their panels, just in case the new owner ends up falling off the roof. Armed with this little bit of safety knowledge and you want to clean your panels, make sure you don't fall off your roof!