With this year's monsoon, we are getting a TON of rain, so my panels have been nice and clean. Unlike earlier this year when I had to get on the roof and clean them.
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Cleaning Panels Difference
- Thread starter skepticcyclist
- Start date
The people I had clean my solar roof also just used a DI system and brushes. They came very clean where they could reach.
I've got a bit of an extreme situation this past month, as we have a couple of small backhoes and bulldozers working around our yard and driveway as we re-do our landscaping and hardscape. As a result, the half of my array on that side of the house has been coated daily with lots of airborne dirt/dust, while the other half of my array on the other end of the house away from the construction is still relatively clean. Both are the same south-facing orientation.
A year ago, each 250W panel was producing about 1 to 1.1 kwh over the day, slightly varying due to different morning and afternoon shading, and slight temp differences from the end panels to the interior panels. Yesterday, the most dusty panels closest to the work only produced about 0.75 kwh each; the clean panels on the other side were fairly unchanged from a year ago. So I've lost about 25-30% on the most dusty panels - but I'm actually somewhat impressed the dirty panels are still getting 70-75% production, being so visibly coated in brown dirt/dust.
Anyways, tempted to go up and blow a lot of the dust off, as I have to do on my deck nearby; but the work will all be done in another few weeks, and will give them a good washing after that....
A year ago, each 250W panel was producing about 1 to 1.1 kwh over the day, slightly varying due to different morning and afternoon shading, and slight temp differences from the end panels to the interior panels. Yesterday, the most dusty panels closest to the work only produced about 0.75 kwh each; the clean panels on the other side were fairly unchanged from a year ago. So I've lost about 25-30% on the most dusty panels - but I'm actually somewhat impressed the dirty panels are still getting 70-75% production, being so visibly coated in brown dirt/dust.
Anyways, tempted to go up and blow a lot of the dust off, as I have to do on my deck nearby; but the work will all be done in another few weeks, and will give them a good washing after that....
So, you didnt have the shut down your system when it's cool? What if there's a thunderstorm during the heat?
There is a slight risk, but with rain you usually get evaporative cooling first, and even in the heaviest rain there is as much water hitting the panels at one time as there is when you wash them.
So, I attempted to clean part of my panels last evening. I used the water fed extended cleaning brush pole with soft water. I didn't go on roof, just cleaned from ground and on the ladder. I noticed this morning that not all streaks, dust were removed.
I will have to go onto roof to do more brushing. May be use this cleaning solution will help?
I don't want to use harsh chemicals that might damage the coating.
I will have to go onto roof to do more brushing. May be use this cleaning solution will help?
I don't want to use harsh chemicals that might damage the coating.
I think I put this earlier in the thread, but I am fairly sure that any professional that cleans solar panels does not use cleaning solutions. They use deionized water. I personally wouldnt use anything but water, but I also am not going up there myself.
The people we used had a multi-cartridge filter that was connected to a hose which pushed the DI water to the roof. It was similar to this one. The unit was on the ground, and they used ladders to get even with the second story roof. At no time did they step on the roof.
Thanks jjrandorin,
I'll try DI water on my waiting stack of panels on the ground, they get even dirtier since they collect the dew and it has no where to drain.
Rinsed panels again last weekend, this time with hose connected to a tap water bib at front of house, got a lot more pressure up to the second story roof, (100ft 3/4in hose) alternated between the shower and flooding nozzles.
Similar to last year, production had dropped to 44-47KWh/day, rose back up to 55-59KWh/day after with almost similar conditions, mid 90s F. Compare with April with cool and clean panels generating over 65KWh/day.
Similar to last year, production had dropped to 44-47KWh/day, rose back up to 55-59KWh/day after with almost similar conditions, mid 90s F. Compare with April with cool and clean panels generating over 65KWh/day.
Nit, but you're not accounting for the expected drop in production between 8/17 and 8/23. I wouldn't be surprised if that adds a few more % difference -- based on PVWatts estimates for south-facing panels in LA, there's a
Edit: Sep also has 3% fewer days than Aug, statistics is fun.
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Matt-FL
Member
I've got a one-story rambler house with a low pitch roof. Easy enough to get up there and clean panels. I probably do it twice a year, if they look like they need it. Takes about an hour, 51 panels to clean. I was using two buckets and a long pole microfiber mop, but I've ordered a water-fed brush pole.
I only use water. Two buckets - one clean, one wash-dirty.
I only use water. Two buckets - one clean, one wash-dirty.
I live on a hill where it's breezy and the panels get a dust film pretty quickly from overnight dew deposition, but my improvement this year after the simple rinsing were nearly the same as last year. Wasn't really a chore since I only rinsed them. They still had that matte look afterwards but it was no longer that brown muddy color. After a bunch of rain, they were smooth again, and I could see the same for some of the panels for the houses down the hill.
What was also noticeable was that measurable production from my 4 panels that were on the side of the house facing the setting sun reached zero around 6pm when dirty, still producing 0.1 KW well after 7:30pm after rinsing.
What was also noticeable was that measurable production from my 4 panels that were on the side of the house facing the setting sun reached zero around 6pm when dirty, still producing 0.1 KW well after 7:30pm after rinsing.
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