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  • Full roof coverage with real + imitation panels

    Hi all — Solar tile/shingle systems like Tesla's include both real and imitation tiles to complete the roof. The reason is that only part of the roof is needed to hit 8 or 10 kW of capacity, and that going over that and covering the entire roof in real tiles would cost a fortune. It would be potentially something like 18 or more kW, not to mention the cost of an inverter of that size.

    I'd like to flip it and explore doing something similar with normal solar panels, which are much cheaper than solar tile systems. Instead of trying to imitate traditional roofs with solar tiles, why not embrace solar panels and complete the roof? Call it solar chic... I think what's sorely missing from traditional solar installs is full roof coverage. I think solar panels actually look pretty good on their own, and that it's the jarring patchiness of partial roof coverage that makes them look less than good.

    Like the solar tile systems, this will require some imitation units to complete the roof – covering the entire roof in real panels would cost a fortune, yielding an oversized 20-ish kW system with a mother of an inverter.

    So... anyone done this? Thoughts? I've not heard of any imitation panels out there, so I assume I'd have to make them myself?

    Secondary idea: Solar panels are surprisingly tough and resilient. I guess it's the quality of the glass – it's incredibly tough stuff. I think there's no need for tiles or shingles underneath solar panels – make the panels your "tile", your roof. I think a roof that consisted of a full coverage panels, over underlayment/felt, over plywood or OSB decking, over rafters would be a very robust roof. In other words, just replace the tile or shingles with the panels, leaving the rest of the structure the same. Anyone done this?

    Thanks for your feedback.

    p.s. These SunPower panels would look great as an entire roof. Making good imitation panels might be a challenge though.

    SunPower.jpg

  • #2
    You will need to give some thought to what waterproof roofing material you want to put under that system. Most people don't realize that a tile roof is not the waterproof barrier. Historically it has been the tar paper and recently other membranes like bituthene or TPO. Your racking or fastening system needs to be able to be comparable with whatever underlayment you choose.
    Last edited by Ampster; 02-06-2020, 04:58 PM.

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    • #3
      One thing to consider is fire code in many areas requires a clear unrestricted access to the ridge line and access to a strip along the ridge line. I do not know how an integrated solar roof deal with it. As Ampster points out the tiles are not the waterproof barrier. If you could work around the fire code issue and you did come up with full coverage solar panels, they would act as a UV barrier for an underlying resilient water proof barrier., like high temp butyl ice and water shield My guess is PV panel glass is tempered for strength and therefore cannot be cut easily. Possibly you could build dummy panels using frame material.

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      • #4
        That would create a immense weight load on your roof. Does not seem practical to me.

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        • #5
          Originally posted by PugPower View Post
          That would create a immense weight load on your roof. Does not seem practical to me.
          It probably depends on the roof. Most recent roofs have a design load that usually accommodates solar panels.

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          • #6
            Originally posted by PugPower View Post
            That would create a immense weight load on your roof. Does not seem practical to me.
            It probably depends on the roof. Most recent roofs have a design load that usually accommodates solar panels.

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            • #7
              Originally posted by peakbagger View Post
              One thing to consider is fire code in many areas requires a clear unrestricted access to the ridge line and access to a strip along the ridge line. I do not know how an integrated solar roof deal with it. .
              Good point. I think the Tesla roof can be walked on. If not the solar part, I do think the glass faux panels can be walked on and trimmed to go around obstructions and to fit the edges.

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              • #8
                Aside from the need to address the fire code issue, which is probably the biggest issue, there is a recent thread that discussed walking on or adding weight to a solar panel and how it's not a good idea from a safety or warranty standpoint. Don't walk, sit or such stuff on a panel. The way they're currently constructed, it won't come to a good end.
                Also, what happens when you need to service a panel in the middle of an array or even get on/at the roof ? Also, good luck on chasing a leak.
                There was a also a thread a couple of yrs. ago about faux panels as a way around some HOA that was concerned about appearances. By the time the fakes got made, it became costly, particularly when it's realized that all the external loadings and so the supports probably need to be considered for the fakes in the same manner as for the real panels.

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                • #9
                  Originally posted by peakbagger View Post
                  One thing to consider is fire code in many areas requires a clear unrestricted access to the ridge line and access to a strip along the ridge line. I do not know how an integrated solar roof deal with it. As Ampster points out the tiles are not the waterproof barrier. If you could work around the fire code issue and you did come up with full coverage solar panels, they would act as a UV barrier for an underlying resilient water proof barrier., like high temp butyl ice and water shield My guess is PV panel glass is tempered for strength and therefore cannot be cut easily. Possibly you could build dummy panels using frame material.
                  There's always BIPV (Building Integrated PV), but those systems don't usually cover an entire roof section and they can usually cost a fair amount more than conventional PV.

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                  • #10
                    Originally posted by peakbagger View Post
                    One thing to consider is fire code in many areas requires a clear unrestricted access to the ridge line and access to a strip along the ridge line. I do not know how an integrated solar roof deal with it. As Ampster points out the tiles are not the waterproof barrier. If you could work around the fire code issue and you did come up with full coverage solar panels, they would act as a UV barrier for an underlying resilient water proof barrier., like high temp butyl ice and water shield My guess is PV panel glass is tempered for strength and therefore cannot be cut easily. Possibly you could build dummy panels using frame material.
                    Good point about fire codes. I wonder how the solar tiles deal with it. I assumed panels could be walked on, which may have been mistaken. I've been reading so much about how they withstand huge hail, hurricanes, etc. that I came away with the impression of indestructibility. And then Tesla's tiles are supposed to last forever or the life of the home, or "whichever comes first" according to Musk...

                    It sounds like this would have to be an engineered solution, something standardized and mass produced. In principle, it seems like we're ready to make the jump to full coverage roofs that replace tile and shingles, but the panels might need to be ruggedized further.

                    I assume that the panels would provide the same mechanical features of tile and shingles -- sunlight/UV shielding, impact resistance, shielding from gross water flow and impact. The waterproofing would be in the underlayment, felt, self adhesive membranes, or what have you.

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                    • #11
                      Originally posted by PugPower View Post
                      That would create a immense weight load on your roof. Does not seem practical to me.
                      This would be engineered for it, new build. We want a steel moment frame, and then a steel framed roof designed for whatever weight it needed to support.

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                      • #12
                        And the perfect roof would be a high strength fiberglass or carbon fiber composite monolithic structure, with solar panels contemplated from the design phase. That way they could be seamlessly integrated, perhaps with a novel attachment system. I mean the kind of roof a company like Holland Composites would design. Strangely, fiberglass is still very expensive after all these decades, and this kind of roof would cost a fortune for a house at the moment. We need this kind of technology to scale to high volume prefab.

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                        • #13
                          I'm not an expert on roofing, and I'm not discarding the idea of a universal roofing material, but I suspect we're many years away from having it, in high volume, with enough history to give consumers confidence in it. Tesla has a first pass, but there's a lot of compromises, starting with cost, and very little history.

                          We have a lot of engineering and history on various types of roofing, and have settled on a few as economical, effective, maintainable, safe for walking, and enduring for sloped residential roofing: predominantly asphalt, with some metal and tile. There are other materials, like EDP rubber, but these are mostly commercial.

                          Likewise, we have some history on the most economical and efficient solar panels: silicon cells with glass top protection, aluminum frames and other layers below and around to mitigate temperature change, handling, and moisture. We made a lot of compromises to get these panels: such as relatively fragile and thin glass so that it will transmit a lot of light and wear well in rain and blown sand. We also developed the infrastructure to manufacture, distribute, and mount these panels.

                          If we were to develop a roofing that was everything above rolled into one: economical, effective for roofing, maintainable, walkable, enduring, good at transmitting light, able to hold silicon wafers without thermal problems, able to protect the silicon and conductors from moisture, long life, etc, we would probably be facing an over-constrained system which does some things well, but sacrifices others.

                          Don't forget that everything we have today in high volume production had problems in the past when first produced, and sometimes again when a new formulation or material was tried. It took years for some of these issues to appear, and then more time for engineers to solve them and prove them.

                          Please work on this. I wish you great luck and speed. But I'm not holding my breath for a good solution in the first half of this decade.
                          7kW Roof PV, APsystems QS1 micros, Nissan Leaf EV

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                          • #14
                            Flisom have lightweight panels. I'm not sure how much they would charge though.

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                            • #15
                              Since when do roofs look "beautiful"? Most roofs have a bunch of ugly things like vents, flues, stacks, antennas, skylights etc sticking out of them. Everyone is used to those with no complaints, but Oh - put a solar panel on the roof and its a different story.
                              Solar panels are beautiful...
                              BSEE, R11, NABCEP, Chevy BoltEV, >2500kW installed

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