To maintain the highest performance of your solar panels the need to be kept clean. The biggest concern is moss growing and dirt gathering on them. If you or one of your neighbours have an active chimney then soot can gather on them as well. All this will significantly reduce the performance of your solar panels and make you loos energy and money. To avoid this you should get someone to professionally clean your solar panels for you without damaging them. The next important thing that might compromise your solar panels are birds nesting under them. Birds might not only be noisy but can also damage panel wiring. To avoid this you should install steel mesh all around them to prevent birds from going under them.
To avoid energy loss of your solar panels you should get someone to professionally clean your solar panels for you without damaging them or your roof tiles.
You should clean them at least once a year unless you have an active chimney or you notice a drop in performance of 5% or more.
If you don’t mind the noise of having birds nests over your roof. Also, keep in mind that birds can also potentially damage wires under your solar panels.