Solar shingles going mainstream?
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cygnus
Feeling the Heat
I've been reading about solar shingles for years. There may be a few products out there but obviously it hasn't been mainstream, mostly because of cost. I'm encouraged to see SolarCity going after this. I believe Musk can get this done the right way.
Dow just gave up the business for shingles and the past is littered with past folks who think they have gotten it right but didn't. Nanosolar was advocating a flat roofing system that would work on commercial and industrial buildings so the entire roof would be PV. Unfortunately their printable solar panels were cooked by UV so they had a limited life.
The multiple articles about the announcement all put a different spin on the same comment from Musk and there just aren't enough details. I don't think it will be a conventional shingle system as the labor related to wiring up the individual shingles is a nightmare. There was an attempt at integrating panels into standing seam roofs but that failed as they were basically a flexible solar panel adhered with glue to the standing seam's base metal. The far more logical approach is use conventional panel construction (tempered glass with cells adhered with EVA)that is proven to survive the harsh climate and come up with an attachment system that is waterproof and can deal with thermal movement. There also would need to be "blank" panels that don't contain PV cells that could be trimmed and custom fit to fill in the gaps.
I envision an approach that is used by some contractors on tile roofing systems. They strip the tile when the panels are going and inset the panels in the hole with tiles filling in the spaces around the edges.Unless NFPA changes their rules, there will have to be a strip along the sides of the panels as well as along the ridge pole that doesn't contain PV. There are also triangular valleys and roof penetrations to deal with. In my concept the panels would go up like sheathing over a waterproof membrane with some sort of air gap to the back of the panel. The panel seams would be sealed with closure strips that would account for expansion and contraction. On the edges and areas that there weren't cells would be blank panels coated to look similar to the PV panels that could be cut and formed in the field. The closure strips don't have to be totally watertight, the membrane underneath is the blackup. Many roofers in my area who do standing seam roofs requires a waterproof membrane under standing seam roofs due to leaks on the standing seam. Any water that gets underneath just runs down and drip out the soffits. Same system could be used for the panels.
The other issue out there is currently new panels come out every week and most panels are only available for a year or two before they are no longer available. I am not sure a lot of folks would want to bet on a 20 year roof that may not be able to be repaired due to lack of repairs materials a year or two out.
The multiple articles about the announcement all put a different spin on the same comment from Musk and there just aren't enough details. I don't think it will be a conventional shingle system as the labor related to wiring up the individual shingles is a nightmare. There was an attempt at integrating panels into standing seam roofs but that failed as they were basically a flexible solar panel adhered with glue to the standing seam's base metal. The far more logical approach is use conventional panel construction (tempered glass with cells adhered with EVA)that is proven to survive the harsh climate and come up with an attachment system that is waterproof and can deal with thermal movement. There also would need to be "blank" panels that don't contain PV cells that could be trimmed and custom fit to fill in the gaps.
I envision an approach that is used by some contractors on tile roofing systems. They strip the tile when the panels are going and inset the panels in the hole with tiles filling in the spaces around the edges.Unless NFPA changes their rules, there will have to be a strip along the sides of the panels as well as along the ridge pole that doesn't contain PV. There are also triangular valleys and roof penetrations to deal with. In my concept the panels would go up like sheathing over a waterproof membrane with some sort of air gap to the back of the panel. The panel seams would be sealed with closure strips that would account for expansion and contraction. On the edges and areas that there weren't cells would be blank panels coated to look similar to the PV panels that could be cut and formed in the field. The closure strips don't have to be totally watertight, the membrane underneath is the blackup. Many roofers in my area who do standing seam roofs requires a waterproof membrane under standing seam roofs due to leaks on the standing seam. Any water that gets underneath just runs down and drip out the soffits. Same system could be used for the panels.
The other issue out there is currently new panels come out every week and most panels are only available for a year or two before they are no longer available. I am not sure a lot of folks would want to bet on a 20 year roof that may not be able to be repaired due to lack of repairs materials a year or two out.
It sounds like they're not thinking about the product as a shingle, but as a larger panel. They're not clear exactly how it will interface with the rafters or trusses, seal, and (hopefully) permit walking on for any work that needs to be done on the roof (not necessarily on the panels) but a roofing panel with integrated solar cells seems like an approach less constrained against optimizing either as a roofing panel or as a solar module than a shingle.
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