Pressure washer for cleaning solar panels
 

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.

Why not a Rainbird with soap injection?

The nice thing about those higher pressure washers is that they can drive a sand blasting attachment. I would think that would keep the dust down. OTOH:

en.wikipedia.org/wiki/Dry-ice_blasting

I cleaned my solar panels again with the 7hp pressure washer. Finished off last year's chainsaw 2-stroke gas mix.
It's just slow.
My current 7hp pressure washer runs a sand blaster great, as long as it's above freezing.

The solar panel pressure washer has an engine now.
My old gx390 engine from the stump grinder. Upon close inspection it looks like it was running pretty rich. The predator 459cc I bought to put on the stump grinder came with extra carburetor jets. A 0-3,000ft jet installed a 3,000-6000 and a 6,000-9,000ft jet as spares. I installed the one labeled as 3,000-6,000ft in the 459cc.
I tore apart the gx390 carb and pulled the jet, noticed the gx390 was running the largest jet out of all 3 jets in my possession.
So I stuck the next smaller size jet I had back in the gx390.
I put a 1mm in there, it was running like a 1.1mm.

I'd be afraid to pressure wash the panels. That, and I can't reach more than about halfway down since I'm 3-high on my roof.

I used a soapy bucket, an extendable window washer, and a hose. Not sure it was good for more than about 5%, though they looked extremely dirty before and clean afterwards.

I let them go when they were new just to see how much dirt it would take before I could notice a 5% drop in peak output. They were extremely dirty. I would have guessed those panels were losing at least 10% as dirty as they were, nope only 4 or 5%.

Hot gx390 on a 4gpm pump. Just need to plum in the unloader valve.
https://ecomodder.com/forum/attachme...1&d=1688349765

I love the smell of clean solar panels and nitrogen dioxide in the morning.
https://ecomodder.com/forum/attachme...1&d=1688439772

I still need a tachometer.
The 4gpm pump with 2.5gpm nozzle seems like it's having trouble getting up to full speed. Restricting nozzle to make a makeshift dynamometer should work perfectly, just need to know engine RPM

With a load #95 was too lean, seemed fine at no load. The above pic was taken with a #98. Still a bit lean. Now it's got a #100 and doesn't seem overly rich.
I think the factory jet was a #104, but I don't have a jet gauge, they're like $75.
I can just about clean my 10kw clump of solar panels off while standing in one spot with a 3mm zero degree soap nozzle.

I ecomodded the pressure washer. I found a hack that allows the UT2 Honda digital ignition to give 4 to 6 degrees more timing. Simply back the coil all the way away from the flywheel. I got 4 degrees of timing at 3,800rpm. Also this gave me at least an additional half horsepower as the throttle was held wide open and the engine hovering at 3,800rpm. With the timing advanced in was able to hit 4,100rpm holding thethrottle wide open.
Next mod I'm going to install a 2 or 4 degree timing advance key. I'll probably do a 4 degree key and I can play with the UT2 coil to fine tune timing.
A "4 degree key" really gives 6 or 7 degrees plus 4 degrees of digital ignition should give me about 10 degrees of total advance. Might need to back that off a hair.
Stock timing is about 20 to 22 degrees. Moving the UT2 gave me a confirmed 4 degrees and the advance key has given about another 8 degrees.

Neat.

Next mod bigger "5gpm nozzles".
Usually more is more.
With a "2.5gpm nozzels" the 0 degree death nozzle is just making mist at 10 feet. The 3mm soap nozzel is more cohesive but only hits like 1,000psi. Maybe the 5gpm nozzel will split the difference a little better.

Gasoline electric hybrid pressure idea.
Not the first time I thought hey it would be cool if I could run the gasoline and the electric at the same time. Well the problems with that are the electric runs like 1,500psi and the small gas one ran 2,200psi and the big gas one runs nearly 3,000psi. So that wouldn't work.
Well recently I tried a 3mm soap nozzel, only makes like 1,000psi but it's got some reach.
Still there's the problem of the big pressure washers unloader valve makes like 3,000psi on the lowest setting. So that probably wouldn't work well on a machine that makes 2,000psi max. Well then I found a 1/4npt stainless steel check valve in my junk collection rated for 6,000psi.
Might be able to make something happen.
Get 5.5gpm at somewhere around 1,250psi out of that soap nozzel.

I bought an oil temperature gauge that goes in the dipstick hole, haven't had a reason to run the pressure washer for more than 10 minutes lately. Well I finally found a reason for an extended run. I ran the pressure washer at 4,000rpm for about 45 minutes wide open cleaning small child puke off our 6x12 foot rug.
My wife's rug looks better than new.
The pressure washer engine oil temperature gauge hit 260F on a mild 80f day. So on a 100f day it would probably hit 280F.
I will investigate adding an oil circulation pump and oil filter and recheck the temperature, then think about adding a cooler.
Just adding a filter and some metal lines appears to have cooled my predator engines oil by around 20F.

Added a pump and oil filter. Just adding the pump, lines and filter turning it on drops oil temperature and it levels off 20f cooler. I'm going to say it needs a cooler.
Also I was getting dirt settling on the engravings on the oil dipstick. After running for maybe 2 hours with a Royal purple oil filter the inside of the engine is as clean as a watch.

I'm thinking about going to a predator 459cc and a 5 or 5.5gpm pump and keep the 4gpm pump as a backup and turn the hot gx390 back into an air compressor.

Oh man this pressure washer saved the day. The septic tank inlet was clogged up with TP. The pressure washer blasted all the compacted TP down into the tank.
I had seen skeptic tank trucks with really long pressure washer guns on them, now I know why.
Luckily I already have a really long pressure washer gun and was able to stay out of the splash back zone.
Being able to clear my own clog saved at least several hundred dollars to a thousand.

Has it paid for itself with that one incident? Partially?

Yeah probably since septic tank service people here live life like a rap video.