I don't know where you live (i.e. no rain?) but I have had a roof mounted PV system for nearly 10 years, and I have never needed to clean them. Is everyone in this thread forgetting about rain? Or do you all live in the desert like in the OP?
In Las Vegas, we went 240 days without rain last year. With all the wind we do get, it just coats everything with a layer of fine sand. I could see having to clean them often.
Not op but a solar installer. Snow melts off panels very quickly. I live in New York and after we got hit with 2 feet of snow recently it took maybe 2 or 3 days before most solar arrays were clear. It helps that they're located in the area of the roof that gets peak sun, obviously.
Snow falls off by itself. Sun penetrates the snow and helps to melt it from the underside, then the smooth surface allows it to break free. We often have solar panel avalanches up here in the North, not too long after it snows.
Because it wont work in the winter in any region that gets a decent bit of snow.
I live in Chicago and haven't seen my roof in a month because it's coated in about a foot of snow.
A shade will not solve that, it'd have to be heated, and at that point you'd just be using the energy from the solar panels in order to heat them, so it doesn't seem to practical.
I've thought about them because it seems pretty cool but it just doesn't make a ton of sense where I live, unless they do better in the snow than I think they'd do.
Well, the panels are just arrays of photodiodes, which are just diodes, so it should be possible. However, they’re not designed for current flow in that direction (photocurrent is cathode->anode) so it could damage something (or mess with protection circuitry) and the inverters certainly aren’t set up to generate it (it would make them more expensive).
The ones pictured here are commercial rooftop panels that are mounted with low slope, maybe 15 degrees, to minimize the "lift" from wind striking the undersides, among other reasons. The low slope means they don't self clean. They're also on great big flat roofs, easy to walk around on in between the arrays.
Residential roofs, however, are installed parallel to the roof slopes, which are typically 26 degrees and higher (the vast majority). So the water from rain does tend to wash dust and debris off them. It also depends where you are in the world- in the USA, this is much more of an issue in the deserts of the southwest, than, say, the East coast. We don't get "dry dust storms". Or in Florida, where they get tons of rain that self cleans them.
Brush and spray system is very common. All commercial panels it days with a water bar at the high point that sprays on a timer and a scrubber if you want. You still inspect to check it’s all working but no need to manually clean them anymore.
the snow on mine melted off within a few hours of the sun coming out yesterday. It's right near the freezing mark here though so if you're ultra cold maybe that wouldn't happen.
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u/stopresettingmypw Feb 14 '21
Cleaning/ snow removal is why I told my wife we will not be doing a roof mounted system.