You have to replace the inverter after 10-25 years depending on its modernity and warranty, etc. But this is more of a planned replacement than an ongoing maintenance thing. Also battery banks can be maintenance-heavy, depending on chemistry, if you're off-grid.

As for the panels themselves, ideally you would have per-panel monitoring and check every so often (once a month when the bill comes in?) to make sure they're all performing as expected, and that there are no damaged or obscured panels holding back an entire string. Micro-inverters or power optimizers, etc. can help mitigate these kinds of impacts.

As others have said, yeah, rinse them off periodically if it doesn't rain often.

Basically, they're not especially maintenance-heavy to begin with, but you want to be at least on top of it enough on a monthly basis to make sure nothing broke (rare but it happens)... you don't want to realize only at the end of a year that a panel's been broken the whole year and the entire string's output was held back because of it.