On military bases in Nevada just send the young airmen out once a month to clean the panels for peak efficiency. My gut still says it's a waste of money, but in some cases it might work out OK.
One problem solar has is competing with the plunging price of nat gas.
I’m getting nat gas bills here in Indiana that are lower than any in my recent memory.
I’ve changed stove, water heater, and clothes dryer from electric to nat gas and my electric bill is way down too.
I’m retired and don’t drive that many miles but if I was driving like the old days (20,000 mi plus / yr) I’d take a strong look at a nat gas car also.