About 10 years ago, I worked with a fried installing solar panels. Mostly residential, but we did occasionally do larger. The information I'm sharing is probably a bit dated, but here are my thoughts:
One of the things I did was a comparison of the benefit to the homeowner of an outright purchase of the system to a lease or Power Purchase Agreement (PPA). I'm sure things may have changed a bit in the ensuing 10 years, but at the time, the leases and PPAs were just an abysmal deal for the homeowner. The first ones I did the comparison on, it was 9 to 10 times more financially beneficial to the homeowner to buy it outright than to do one of the alternative arrangements, even if it meant refinancing a mortgage or taking out a home equity loan to do so. By the end of my time in that business, the guys pushing the leases and PPAs had gotten a bit more competitive: buying outright was only 7 or 8 times better.
One of the things we found was that the people who were pushing the leased or PPA systems would quote someone a price for a purchased system, but they often did so at a greatly inflated price, so their lease or PPA looked better when compared. It can be very difficult to compare the net benefits of the various systems, if that sort of analysis is not something you have experience in. The lease/PPA companies don't do anything to make it easy either. The smart homeowners made a point to get quotes from more than one installer, and ideally at lest one from a supplier who was not pushing alternative financing arrangements.
The middlemen are in business to make money also. The only way I would ever consider one of these lease agreements would be if I did not have the credit rating to get a home equity loan or other financing at decent rates.
_____________
As to maintenance: there isn't much. If you live in a dusty area, hose them off once in a while. that's pretty much it.
We installed quality panels from "first tier" manufacturers (and regularly checked on the manufacturer's financial condition as a means of estimating whether they would still be around years down the road.) The warranty was 25 years on the panels we installed. If I recall correctly, the panel we used were warranted to still put out at least 80% of their rated power after 25 years. That may well have changed over the past decade since I was involved. Many of the panels installed 40 years ago are still running today, and the technology has improved (they do degrade over time, losing a bit of max output over the years, but still provide usable power.)
The Microinverters we installed (mini inverters which attached to each panel) had a 20 or 25 year warranty. They are a bit more work to replace if roof mounted, since you had to go up on the roof and most likely unmount the panel to get to them). The string inverters typically had a 10 year warranty (larger units where you tied a string of panels together and fed them into a big inverter mounted where access was easy). So they would not last as long, but they were very easy to replace: not much different than installing an appliance that was hardwired in. String inverter efficiency has improved to the point that when we installed my system, I used that rather than micro inverters. I figured the ease of replacement outweighed the possible need to remove things from the roof, and even if I factored in the need to replace the string inverter at 10 or 12 years, the cost was not all that different.
In all the time I was working with this business, we had only one microinverter fail, and it did so within a few weeks of installation. This happened on my own system, so we just submitted the warranty claim, got the replacement, and put it in.
