Last week I cleaned my 22 panels after almost a year on my roof. I've read that the power difference, if any would be negligible after cleaning under normal circumstances. Here in Northern California we had epic rainfall this spring, and I figured that would get me through to this winter. I noticed though that they were looking quite dusty. After getting on the roof and looking closer, they looked even worse, and I decided that they needed cleaning.
Went to Lowes and got the biggest professional window squeegee they sold, an 18 inch Ettore model and the corresponding 15 foot expandable pole. I also bought a cloth window washing scrubby tool. After dragging the hose up, the normal water pressure from the hose nozzle was plenty good to wash off the dirt. And there was a great deal of dirt. More than it even appeared just by looking at them. I have hardish water in my area, so as soon as I washed the panels down a few times, I squeegeed them to remove the water and dirt. I worked from the bottom, pulling the dirt and water towards me. The whole process only took about 15 minutes to clean the entire array. Each panel was basically three swipes with the squeegee. Never needed the cloth scrubbing tool, nothing was stuck on that didn't come off with the normal water flow.
This was all done last Wed, the 20th. Today I took a look and my readings and the increased power after cleaning is quite noticeable, as seen in the graph below. At least 4 KWh's more per day. Worth the time for sure. So I'm guessing I'm going to start doing quarterly cleanings. Lastly, I don't live near any construction or busy roads, just the normal suburbs.
Steve
ScreenHunter_615 Sep. 25 11.56.jpg
Went to Lowes and got the biggest professional window squeegee they sold, an 18 inch Ettore model and the corresponding 15 foot expandable pole. I also bought a cloth window washing scrubby tool. After dragging the hose up, the normal water pressure from the hose nozzle was plenty good to wash off the dirt. And there was a great deal of dirt. More than it even appeared just by looking at them. I have hardish water in my area, so as soon as I washed the panels down a few times, I squeegeed them to remove the water and dirt. I worked from the bottom, pulling the dirt and water towards me. The whole process only took about 15 minutes to clean the entire array. Each panel was basically three swipes with the squeegee. Never needed the cloth scrubbing tool, nothing was stuck on that didn't come off with the normal water flow.
This was all done last Wed, the 20th. Today I took a look and my readings and the increased power after cleaning is quite noticeable, as seen in the graph below. At least 4 KWh's more per day. Worth the time for sure. So I'm guessing I'm going to start doing quarterly cleanings. Lastly, I don't live near any construction or busy roads, just the normal suburbs.
Steve
ScreenHunter_615 Sep. 25 11.56.jpg
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