Wow. I had heard rumors that some solar plants used more water than thermal plants. I can how that could be the case with daily washing.

Can you switch to washing based on how much dust has accumulated?

Maybe try to control the amount of dust that blows in. Fencing or trees can help reduce the dust load a bit.

You're in a (relatively) brand-new industry. Very few standards of any kind. But there are common-sense things you should be doing such as: 1) apply the liquid at as low a pressure as possible, 2) do not use soaps, etc., 3) ensure all your electrical connections are moisture proof (note: there ARE standards for this!). Instead of a "pressure" wash, which is probably what you're doing, try using a simple scrubber - like the one used for cleaning windows. Again, use only water - not soaps or cleaning agents.

Above all - figure out exactly where the fault is occurring. Is it in the panel, the wire run between "turning motor" and panel, between controller and "turning motor", or at the cable terminations at each location? Then address the specific issue - not just a symptom.

Converting energy to motion for more than half a century

I agree with Gr8blu's suggestions but would go much further.

You're literally torturing the panels and I'd expect them to all fail. If you're doing this during the day you have panels that will be almost too hot to touch that you're applying water to! Serious thermal shock that will open the seals. This shock would not normally happen. Rain doesn't generally show up in intense sunlight. It gets overcast dropping the panel temps before water starts landing.

You're blocking panels and killing output on any banks you're cleaning. This is costing efficiency, the whole reason you're washing them. If you clean them at night you nether thermally shock them or cause efficiency loss. The water will be evaporated by the time the sun gets part way up the sky and well before the panels get hot.

No pressure washer EVER. Use standard window washing techniques. Spritz with RO or distilled water and use a wide squeegee. It's way faster than any other method too. If you need cleaner find one with no surfactants. Sufactants cause water to wet better and that will transport it thru seals much faster.

Keith Cress
kcress - http://www.flaminsystems.com

I would add you are torturing your budget as well. I’ve never heard of daily cleaning for a solar field of that size. In dusty desert or agricultural regions, we may see 2-3 washings per year.

For a 1.25MW site, I wouldn’t even expect to see staff on site on a daily basis. Monitoring performance remotely and dispatch as needed.

JFPE

Thank you all for the responses. I have read somewhere that you can even plan the cleaning of panels with irradiation data. As soon as irradiation values fall below 200, you clean the panels.