Solar panel maintenance is very costly?
Welcome to the forum
The panels themselves are extremely low maintenance, it's the other components, especially batteries, depending on chemistry which demand maintenance. Rule of thumb panels 25 years, occasional cleaning, electronics ~10 years +/-, batteries 5-10 years or less depending on how they're treated and what is chosen, or if they're needed in the first place.
The average cost of an annual inspection for a household rooftop solar PV system is approximately $150.00. The average cost of having your panels cleaned by a reputable solar installation company ranges from $10.00 – $20.00 per panel.
Cleaning a panel is like washing a window though safety issues may present. The panels are the easy part. Heavy rains will also clean them - enough - most of the time - in theory. I've never really cleaned my panels other than brushing off snow.
Part of the key to solar is proper installation. I did things right the first time and that is pretty free of problems. I experimented and stuff the second time - that system has occasional issues. It was mostly for fun anyway.