Solar Roof

Cleaning your Solar roof

With all the ash here in California, it was time to clean our solar roof. This was trickier than I expected and I went through 5 different processes to figure it all out. I wrote it all up here with photos:

Now I wish there was a Roomba to clean the roof!


  • Get studded tires for your Roomba. :-)
  • Just my two cents...I would highly recommend NOT using a pressure washer directly on any PV panel of any type.
  • Based on 13 years of owning solar and cleaning my own panels - there is no substitute for friction to clean panels. Water source is just for rinsing. Getting on the roof has always been a challenge (doesn't matter what type of roof - a slip and fall can be deadly or at least highly injurious.). Long extension pole with a soft brush (I use a 24 inch soft broom head on a 23 foot extension pole).
    For a single story home - everything is done from the ground or a ladder. The weight of the pole and the broom head is enough for cleaning...just drag it back and forth.
  • @greg - I would agree on a typical solar panel - it would be easy to blow through the seals around the edges and contaminate the panel. For the solar roof, it's construction is quite different, where it's just a sheet of glass. Still, I'd only use the lowest setting, suitable to wash a car, not strip paint from cement.
  • @jones - For panels, the pole system works fairly well. I used it myself when I had individual panels. The difficulty with a solar roof is the size. My 11 solar panels only had 190 sq feet total to clean. It was a chore but was doable from the ground. I'd spend about an hour doing the cleaning, usually split into two 30 minute sessions before I got tired of lifting the long pole.

    The solar roof is an entirely different game. My solar roof is 3600 sq feet. A massive difference. To be fair, only about 1/2 of that are actual cell panels, but from the ground (or ladder) you can't tell which are cells and which are just glass. It would also look bad to just clean specific tiles.

    There are some spots where my 24 ft long pole will not reach as well. I did one section with the pole method, and I'd guess it took about 5-10 times longer than other methods. So it would take maybe 20 hours to do my roof with a pole and still leave some areas untouched. That's a lot of back-breaking work - all done on a ladder that has its own risks! Other methods took about 2 hours.

    I do agree that falling off the roof is bad. I think copying the roofers would be best. You'd rope yourself to a pipe or other item so that if you did slip, the harness would prevent you from falling. There is a lot to be said for hiring a pro, although I don't know if any are set up for cleaning solar roofs yet.
  • @TeslaTap - The whole bit of safety puts a real spin on this. You obviously have the experience and skill to make a good choice. Esthetics is important on your glass roof - no doubt. It's like window cleaning - you don't clean just one and you remove the screens to clean the window behind. I would probably be pretty obsessive if I had that roof.
    Have you considered a permanent anchor point that you could use for a harness ?
  • @Jones - Yep, I thought about the anchor points that they used (but removed) during the roof installation. I don't quite know where they are and it may require pulling up some of the ridge tiles. I do have several vent pipes that are very strong and may use them with some kind of attachment.
  • Around here, vent pipes are made of ABS, with galvanized steel flashing at the base. No way in he|| I'd trust my life to one of those.
  • Here's an "oh no" moment for ya...
    I have a 3 kW segment of SunPower panels using microinverters. One of the inverters failed and in order to replace it - they ended having to replace all 10. Yep - pull up 10 panels, detach the microinverter and put them back...all under warranty. They sent a crew of FOUR (I have a low slope asphalt shingle roof). I walk up there all of the time with no issues (I'm 67). One of the guys on the crew was a safety officer. When they arrived - I was already on the roof because I like to document things - pics - notes - I like the tech stuff. Safety officer said they were not going to start until I came down (and stayed down) even though there is bleacher seating on the east slope roof away from them. Unfriendly discussion ensued, but I wanted the inverters fixed, so I came down. Set up a directors chair not he ground in the shade to watch. They proceeded to put three holes in my roof for anchors for their gear. Then they put on their gear with a shackle on each lead about half the distance of each rope from the edge. Each time they moved...the shackle bounced across the face of at one or two panels. You guessed the time they were done, they had shattered the face of one of the panels. Safety guy approached me to suggest the panel was broken when they arrived. That discussion was a bit more intense as I reminded him that I had been on the roof at the time of arrival and had time stamped pictures of the array in good condition. By the time we were done "discussing" - I had a date for a replacement. The replacement session (for ONE panel) had a team of 7...3 supervisors, a safety guy, crew chief and 2 lucky souls with all eyes on them as they peeled up one panel to replace it.
    Basically - the point is to be careful about shackles and carabiners if you decide to go that way. Also about good climbing rope that does not get caught on edges or chafe under use. And lastly as Greg suggested...the vents are likely ABS (mine are as well) - not good anchors.

    Are you not entertained ?
  • @jones- Smart taking pictures before the start!

    Every house is different. I didn't realize some houses use plastic vent pipes and I agree that would be a very poor attachment point!

    My vents are all galvanized steel and stick up about 10". They are very strong and well secured in my house. On one vent, I used to have a 15-foot high mast with a rotor and the largest FM/VHF/UHF antenna I could buy (it was a monster). Zero problems or leaks, even in large wind storms. I didn't need it anymore and removed it before the solar roof install.

    On the Microinverters, the utilities changed some requirements, and while old inverters are grandfathered in, you can't install the old versions today. I suspect that's why if they replaced one, they had to replace them all to maintain compatibility and meet utility requirements (at least in CA).
  • During the day after Solar City was done installing and testing my 5kW array (19 of 265W panels) in 2015, I went up into my attic, turned the lights off, and gazed upward. (It's a good way to see if there are any *obvious* holes in your roof.) I saw two holes. They were at each of the harness tie-down attachment points. The lag bolts they use for those things are huge, and probably represent the biggest liability they have for roof holes.

    I called Solar City (I got right through), and they had a local roofing contractor out to my house *the next day*. He fixed it right up, and I wrote a check to Solar City for the final payment.
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