Dirty vs Clean Solar Panels | Testing Power Output Loss 

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So many RU-vidrs and influencers give false and dangerous information but not you. Thank you for sharing responsibly and giving the consumer the best options to maximize energy by hiring a professional solar panel cleaner.

Very reflective substances like white flour will keep the dirty panel cooler, keeping the panel efficiency higher. It would be interesting to repeat the test with darker dust or dirt.

Good video! Here in the Arizona desert, a lot of people use 16% degradation as a worst-case loss, due to film, dust, and bird poop. We use a high number, because we get a few dust storms every year, plus dirt devils kick up a lot of dust too. When panels are dirty, they may not put out full voltage, so designing for a little extra voltage headroom helps startup.

I gain about 15 % more output when I clean my panels. I just wet the panels, use Dawn in a car wash soap sprayer and rinse.

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I'm astonished that the dirty panel produced that much power. I'm the type of guy who would simply by one extra panel for my array of 12 panels so I didn't have to clean it as often.

Where I am in Arizona - totally off grid - I see an almost negligible difference between clean and not fully clean panels. Granted, my panels are off the ground and there is no trees around them for pollen, but they certainly get that light layer of grime/dust. I’ve stopped cleaning them as I might see a 1-3% change at most.

I wonder if car detailing products such as wax or ceramic coating would benefit the surface of solar panels.

Thanks COOP ...

perfect job and explanation, Thank you.

Good info.

We live where it doesn’t rain for months and seeing dust, etc on my roof mount panels makes me crazy. But upon cleaning a few panels the panel monitor shows zero difference between the cleaned and dirty panels. No particular conclusion at this point other than visible contamination doesn’t necessarily translate to measurable performance degradation. Still makes me crazy though and might explain why the long established company I had do my design and installation doesn’t have a cleaning interval recommendation.

So I bought a Vtoman 1800 with extra battery, giving me 3000watt hour of power, in case of power outage. I bought a 100watt solar panel. Can I use it through my home window as I live in a cold climate ? Thanks

I have 2 200watt renogy solar suitcases and one all ways makes 1 or 2 ah more than the other. Need to hook up a meter and just clean the dirty one to really see the difference 😮

While PV panels generate energy through the absorption of visible light (mostly), the type of contaminants determine the losses. Because of that, the appearance is not necessarily an indicator of the amount of loss. However the cost of the lost energy must consider the (commercial) cost of cleaning the panels. Numerous tests have shown that cleaning the panels on a regular basis is not cost effective in this scenario, unless it's in an area of high fall out.

New Solar Panel owner here, but not turned on yet. I assume rain is enough to wash panels , so if you have enough days of rain, you should be good?? I live in VA and we do have enough rain, but every so often, like this Spring, we get many days with no rain and a good dusting of pollen. I wasn't thinking about having to wash my panels until this past Spring and seeing this video. Thanks.

OK, based upon your data I would say that washing panels once per month is OK..and that is why the big panel farms are not that worried about it, saying use biggest watt panels and do not worry

How about demonstrating that the panels are equal in output when both clean before demonstrating a delta due to dirt.

Wouldn't the MPPT working to maximize power cause fluctuations in watts incoming at any given moment? If so, measuring the watts at a point in time, risks being inaccurate compared to measuring the total power generated over a decent amount of time. What I mean is that if you measure at a time that just happens to be a short term dip on one panel/MPPT, and a moment later, measure a short term peak on the other panel/MPPT, then you're comparing apples with oranges.

Once when my panels were being installed one of them was propped up against a wall. When I walked by I hit just the right angle and was blinded by the sun reflecting off the panel. Later I got to thinking: that light in my eyes was sunlight that was not reaching the cells! So I wonder: is a nice pristine shiny panel really the best thing? You tests do show a degradation, but it isn't as much as I would have thought. Maybe it was partly offset by the diminished reflections off the glass? After all, the light does not have to be focussed, the dirt might just diffuse the light and that is all that is needed.

I find by running the garden sprinkler on my panels I can easily gain 10%

Looks like you are shadowing part of the dirty panel.

LMAO thats not the usual dirtiness a panel will experience on roof or mounted anywhere. I live in desert and the panels get dirty they get washed by rain they get dirty and washed by rain... I do not clean them at all now since i discovered the highest difference i ever got was 3% reduction.

6% loss every day is a big difference

I’m not buying this argument yet. Solar panels of same make and model have different outputs. No two are exactly alike. Until you know a clean panel’s baseline output, these results with the dirty panel are meaningless. So, side by side and both clean, what are the output differences? If by chance, they produce the same results or close to the same, then I believe your results with one of the panels dirty. If they don’t produce the same or near the same results, then more study is required. I’d recommend you rerun this experiment and let the results of two clean panels be your control. Then do the dirty part!