Dirty vs Clean Solar Panel – Power Output Comparison and HowTo



Why clean your panels every year?? Check out this video to see, how a simple 5 minute cleaning can significantly boost your power output!

These are also some of the highest quality 100W available panels available in the USA today. You can purchase them directly at:

We hooked up a dirty solar panel to a constant voltage DC electronic load. We set the voltage to 36V and found that our dirty panels were outputting about 4 Amps which is equivalent to about 145 Watts. Once we cleaned the panels, we saw in increase to 5.1 Amps (183 Watts), which is the full power you can expect in typical conditions.

The amperage data was linearly mapped to a visual power meter to show the decrease or increase in power in real time.

The dirty panels were outputting 26% less power than when fully clean.

30 comments

  1. This helped in more ways than one. I have a dj speaker that wouldn’t turn on. I have solar, and my panels were dirty and not letting me get more than 117 volts. After cleaning i got 118-119 and my speaker turned on. Thanks for your great video. I would have never figured this out.

  2. Nice to see clean panels again but the numbers are missleading unfortunatly as you didnt wait for them to heat up back to working temperature after washing. Thats why you see steady wattage decreasing in the end of the video. Average temperature coefficient of monocrystaline panels is around 0.5% per degree celsius, so assuming you cooled down the panel from 60° to 30° celsius by washing you gained 15% more output from temperature alone. You can check this by cooling dirty panels from backside with a hose or something, power output will increase even no grain of dirt gets removed. But still then you get realistic 5-10% more power from cleaning depending the amount of dirt on the panel whats still worth to do so 🙂

  3. I cleaned my panels 2 weekends ago. Some of my panels went up 30+ percent. They were coated in dust after 8 years. No bird poop. Makes me sick to think of the power I threw away. Going to clean every six months from now on.

  4. The bird poop is enough to shut down a section of the panel that’s why when cleaned there’s a big difference in the generation

  5. The pannels should have been allowed to heat up again for a more accurate comparison. A 25% increase is misleading it’s more like 2% anywhere on the internet.

  6. Very nice demonstration. Nice to have live output (green digits) in lower right corner monitoring electrical output. Keen eyes (at time stamp 3:15) will notice how the output tanked to 15 watts simply by having your arm & body shadow interfering with panels. Demonstrates that dirt & shadowing is one of the most detrimental cause of poor output. Simply by removing the poop (aka: shadow) immediately increased output (yea, I know, critics may contribute the output to the cooling effect of water. …. whatever). Well done. Additionally, you created an artificial MPPT effect by holding voltage constant. Nice way of reducing variables for a more accurate final measurement. My only constructive criticism to hush the negative critics would for (RPS Solar) to enter a final photograph of output after the panels had warmed up again after water evaporation and panels returned to a stable "hot" running temp due to sun exposure. You made note of this in comments/replies, but to satisfy the lazy viewers who don't scroll down to read…… Anyway, nice vid. I support your demonstration.

  7. Panels should be cleaned at least 1 time a month to maintain efficiency. Each year they get older, 20 year panels last 15 nowadays.

  8. Thanks for nice video clip. But it is not recommended to clean the panel during the daytime. It sometimes causes potential induced degradation (PID). Please clean them in the sunset or sunrise.

  9. 1:03 NO. Actually out of a 200 Watt panel on a clear sunny day, you SHOULD be producing 200 Watts, not 180 to 190 watts. Just more false advertising with the infamous words, "Up To" inserted in the performance claims. It would nice if manufacturers could state "A Minimum Of" in those inflated performance numbers.

  10. this video has been so revealing. Now I know what to expect. and when to wash, and when I can safely ignore dust.

  11. How does it work after the sun is down? Say, if I was using this for water supply for a home? does it use a UPS system as a backup power storage or what?

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