I'd be all for hosing them down . . .. From the ground.
As for cost/benefit, my power bill averages $40-45/month, so I would need to get at least 20+ years out of a system just to cover the install cost. No way in hell I would deal with any of those leasing companies who camp out at Coscto/Lowes/Home Depot and their sketchy contracts. IMO the tech still has a ways to go, but if PGE starts regularly shutting down power where I live, that would certainly push me in that direction.
We did some math on putting solar on our SF roof top a number of years ago.
Rough numbers are based on that.
1 Might as well put new roof up while putting on solar - $15,000
2 Cost for average set of panels, wiring, permitting - $25,000
3 Cost for good battery storage (optional but useful?) - $20,000
4 Average power and gas during 6 summer months - $300
5 Average power and gas during 6 winter months - $600
6 Still have to pay PGE line fees monthly - so $100 a year
Therefore power and gas is approximately $1000 a year, so it would take 40 yrs to recover cost at the low end.
Barely had the $ to buy the place in the '90s, so couldn't afford the upgrade then. I could put it in now, but unless I stay put and live another 40 years here, could recover cost (but I could put it in and sell the place, and add it to the sale price, but it would be an amortized gain, so....) Then I just rebuilt my stairs, etc., and blew up my savings, so now I definitely can't afford it now.
I think new roofs haven't gotten cheaper, but maybe solar installs have(?), so the above figuring is possibly invalid, but a reasonable starting point for a single family home in SF.