[oil pan 4]

An electric pressure washer would be nice but not realistic. My electric pressure washer with a triplex clone pump and 56c frame is only good for about 2.2gpm at 1,500psI with a typical spray nozzle. That's tiny.
By comparison my much more powerful gasoline pressure washer has a 7hp motor and makes 2.5gpm at up to 2,500 psi, that's ok for solar panel cleaning but still slow.
Clearing solar panels with a pressure washer is kind of like cleaning a parking lot. You want to put down as much raw water power out of that nozzle as possible.
So I got a new 4gpm up to 4,000 psi triplex pump for my honda gx390 for $250 shipped out the door. I'll likey run it about 4gpm at 3,000psi depending in the nozzle because the honda gx390 is only going to make about 12hp here in this thin air. And 4@4,000 would take around 15hp. A 16hp V-twin would handle it.
I think a 390cc engine pushing 4gpm at over 3,000psi should be sufficient to clean some solar panels.

Why now? Because no one is thinking about pressure washers during the winter. So I figured I would get on ebay and make am offer.