Do I need to clean my solar panels?

Generally you don't need to bother cleaning your solar panels. Unless you're up there spinning tyres and shooting exhaust particulates at them!

If you're in a dust-prone area, under fig trees, are regularly visited by pigeons or have horizontal panels, then you'd need to clean them more regularly.

Otherwise, it only makes about 5% difference to your production on average if you clean every day. Once a year is probably worth it if you enjoy doing it yourself. Not really worth paying someone for it though.