Pressure washer for cleaning solar panels

[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.

[freebeard]

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

Dry-ice blasting is a form of carbon dioxide cleaning, where dry ice, the solid form of carbon dioxide, is accelerated in a pressurized air stream and directed at a surface in order to clean it.

Compared to other media blasting methods, dry-ice blasting does not create secondary waste or chemical residues as dry ice sublimates, or converts back to a gaseous state, when it hits the surface that is being cleaned. Dry-ice blasting does not require clean-up of a blasting medium.[2] The waste products, which includes just the dislodged media, can be swept up, vacuumed or washed away depending on the containment.

[oil pan 4]

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.

[oil pan 4]

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.

[redpoint5]

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.

[oil pan 4]

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%.

[oil pan 4]

Hot gx390 on a 4gpm pump. Just need to plum in the unloader valve.

[oil pan 4]

I love the smell of clean solar panels and nitrogen dioxide in the morning.


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

[oil pan 4]

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.

[oil pan 4]

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.