Note: This is another entry in the 'Solar on a Strata' blog series.
When we installed the panels on Central Park, we expected to clean them annually at the same time as windows and skylights.
The panels have a type of glass designed to shed dust, and generally the rains have kept them pretty clean, with the exception of a few bird droppings.
In early March I took a good look and found a row of grit along the bottom edge of every panel (see right). So as a test I took the high-tech equipment in the photo above - a bucket, a small nylon broom, and a few drops of dish soap - to the roof. In total it took about 40 minutes to clean all 60 panels, including a couple of trips down the hatchway to refill the bucket. Next year, I'll use a 20 litre pail and do it in one trip.
This has been the sum total of annual maintenance so far.
I've also attached the latest electricity production graph to the end of March. So far we are about 7% over the estimate from pvwatts, the website I used to predict electricity output.