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Solar roof tiles and snow
- Thread starter Zorg
- Start date
I'm also interested in this question. We live in the Tahoe area at 7800 feet where we get up to 500 inches of snow in heavy winters, with typical snow being in the 250 to 350-inch levels. Our storms are usually interrupted by periods of clear sunny weather, often warming into the 30s and 40s+ for days and sometimes weeks. Thus, I'm wondering how the v3 solar glass panels would do in terms of shedding snow (12:7 roof slope) and melting the snow that does accumulate during storms (which can be a couple feet). Any experiences to share on these questions?
The northern Virginia / DC / Maryland area is not snow country, but we do get occasional storms. This thread covers some challenges we saw with a storm last month:
Solar Glass Snow Avalanches
Solar Glass Snow Avalanches
Is your roof 12:7 (~60°) or 7:12 (~30°)? If the former (which would be essentially equivalent to 20:12, the current max pitch listed for Tesla solar roof installs) I would expect snow to slide off the roof fairly quickly, based on the bit of experience from the storm @trautmane2 referenced. Even his roof (which I recall he mentioned was about 45° in places) seemed to have snow sliding off more quickly than ours (at 34°). Obviously this is a bit different from what you might experience with some of the huge snows you get out there, but I would guess the glass roof would tend to shed the snow pretty quickly as long as you don't run out of room for it to pile up - we got good piles in a line a few feet from our house where all the snow slid off, which did end up being something of an annoying, icy mess to remove from our walkways.
To further combine these two threads, I received some samples from a company TESLA referred me to that sells "sno-guards." They adhere with an adhesive to the inactive tiles. Has to be done when temps up over 50 for proper curing, so I am waiting until spring. That gives an added advantage of the company will have its "wide" version out then, as well, which will help on roof surfaces where you are only able to apply the guards at the bottom of the roof because the remainder is active. The company maps out where you should put them, and each guard costs about $1.40. Supposedly Tesla is working on a similar product, as well. Still working through all the ins and outs of this one. Should help with the avalanche issues noted in that thread, however.
Thanks for your question and comments. It's a 7:12 roof (7" drop over 12" horizontal), thus ~30% pitch. And, yes, it's a 2-story building, so we have significant room for snow buildup; whereby that causes a challenge for the walkways.
That is shallower than our roof, so I could imagine that could build up more snow before dislodging. I do think it will slide off - either when it hits a critical mass (which is what ours did) or, as it melts, it will likely create a water layer that will cause it to slide. As @dhquigley posted, there may be a benefit to snow guards to hopefully break up some of those avalanches that might come crashing down. Not sure if you have gutters as I recall that to be less common in your area, but that might also influence the need for guards.
No gutters; they would never survive the snow. This is new construction, so I could have the snow guards installed and do see some houses in the area with them, but I believe their purpose on those houses without solar, is to prevent (and break up) shedding. I want shedding to occur and have designed the walkways to accommodate avalanches. I'll inquire with my architect on the subject of guards. My concern is that snow builds up, doesn't shed, and my solar production goes to zero for long periods. I definitely will not be going on the roof in the middle of an icy winter to try and remove snow.
The other thing I'm wondering about is the rest of my non-solar roof area. My current roof is metal, which works really well up here in the heavy snow, but I will be replacing the entire roof during construction of the new addition where I am going to add solar. Should the entire roof be of Tesla solar panels and their inactive panels, or can I combine the Tesla roof with a traditional metal roof for the non-solar areas?
The other thing I'm wondering about is the rest of my non-solar roof area. My current roof is metal, which works really well up here in the heavy snow, but I will be replacing the entire roof during construction of the new addition where I am going to add solar. Should the entire roof be of Tesla solar panels and their inactive panels, or can I combine the Tesla roof with a traditional metal roof for the non-solar areas?
It is an interesting issue, and I wonder if you could get somebody at Tesla who has thought about solar and snow guards. My understanding (having had something on our old roof) is that they are primarily intended to prevent the avalanches and do so by breaking up/slowing the snow as it slides down the roof and also retaining/catching some of it. So it likely would take longer (though how much, I don't know) for the snow to disappear from the roof. However, I would expect that to be mostly on the lower part of the roof. So, depending on your roof size and energy needs, it might be possible that the retained snow would collect on inactive tiles near the bottom of the roof, while the PV tiles are placed higher up and are clear. Of course, based on your description of your plans, it may just be acceptable to have those avalanches.
Given what I saw with how Tesla installed our solar roof, I would be surprised if they supported anything other than their shingles (whether active or inactive) on a given roof face - and I'm not even sure if they would be able to support something else on an adjoining face. If there are disconnected roof sections that are not going to have solar, those could certainly remain metal. But, I would not be surprised if the glass tiles shed in a similar way to the metal - it certainly seemed to shed more quickly than our old roof (though, as I note, the old, slate roof did have guards on parts of it as well.)
Did you end up installing the Tesla roof? We live in Truckee and are considering same. Would love to hear about your experience.
Apparently, there is no certified solar roof installer in Truckee, per Tesla website