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  • Prep for solar on new home

    I am building a new home with a custom builder who has no experience with solar. I also don't believe I can swing the cost of adding solar at this time. What makes sense to do now, while all options are open, to simplify installing solar in a few years? Thank you - David

  • #2
    Do you have TOU billing where your house is?
    Are there going to be shadows from other buildings or trees?

    You should make sure that the roof is well situated with as much clear unshadowed exposure as possible, and no obstructions on the solar potential part of the roof ( no vents etc). Use good long life shingles ( not builder grade).
    OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

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    • #3
      I would start with infrastructure. A lot depends on where you are located. The building code in my former hometown required conduit from the electrical panel to the roof for future solar systems and a 30 Amp 240v circuit in the garage for a future EV charging station. I would start with that as a minimum.
      Does your home have a flat roof or is it sloped with shingles or tile?

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      • #4
        Originally posted by ButchDeal View Post
        You should make sure that the roof is well situated with as much clear unshadowed exposure as possible, and no obstructions on the solar potential part of the roof ( no vents etc). Use good long life shingles ( not builder grade).
        Second those statements.

        Putting vents all to one or two stacks and on the north edge of the roof will help with shadows/ ease of adding panels. (Assuming it is northern hemisphere). And it's fewer roof penetrations, which is also good.

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        • #5
          If you design for low energy use with insulation, effective sealing techniques, efficient appliances, and then use sensible and appropriate passive solar techniques such as fenestration locations, overhangs for shading and other sensible and appropriate measures for passive heating and cooling, you can and probably will lower the HVAC loads by a significant amount. doing so will allow any PV system or other solar appliances to be smaller. That translates to lower initial costs for energy bills with or without active solar, lower costs for samler active solar when it is designed/added and an easier install. You'll have a good handle on HVAC loads before you build. That will make PV sizing a lot smaller as well as an easier task to make the design so that the PV location can be optimized if placed on a roof. BTW, ground mounts, while not alweays possible and a bit more expensive in terms of initial cost, provide a lot of benefits that may be worth it. No one ever said solar equipment MUST be on a roof.

          New builds are the best chance to get it right, but keep in mind the goal is appropriate and probably low energy use, not PV as an end in itself.

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          • #6
            Originally posted by J.P.M. View Post
            If you design for low energy use with insulation, effective sealing techniques, efficient appliances, and then use sensible and appropriate passive solar techniques such as fenestration locations, overhangs for shading and other sensible and appropriate measures for passive heating and cooling, you can and probably will lower the HVAC loads by a significant amount. doing so will allow any PV system or other solar appliances to be smaller. That translates to lower initial costs for energy bills with or without active solar, lower costs for samler active solar when it is designed/added and an easier install. .............
            New builds are the best chance to get it right, but keep in mind the goal is appropriate and probably low energy use, not PV as an end in itself.
            As long as we are on the topic of energy conservation I agree the best return is on energy conservation.

            If you are building in California, every new home is required to comply with Title 24, which deals with the energy efficiency of the design. You should familiarize yourself with that report or find out if your jurisdiction requires a similar analysis. If there is still time to make changes ask your architect or whomever prepared the report where there might be opportunities to enhance the energy envelope of the home. Those could involve additional insulation where possible and other enhancements suitable for your area. A lot depends on your location. Let us know where you are located and others may chime in with more specific ideas related to the weather in your location..

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            • #7
              A final step to optimize the house for solar, is make the roof angle, the preferred angle for maximum solar harvest, or as close as the design will allow. if you are able to align the house for best solar harvest (due south, or SSW) that is also a factor. Anything you do to make things simpler and faster for the solar install. Maybe install the solar conduit to the roof now.
              Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
              || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
              || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

              solar: http://tinyurl.com/LMR-Solar
              gen: http://tinyurl.com/LMR-Lister

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              • #8
                Originally posted by Mike90250 View Post
                A final step to optimize the house for solar, is make the roof angle, the preferred angle for maximum solar harvest, or as close as the design will allow. if you are able to align the house for best solar harvest (due south, or SSW) that is also a factor. Anything you do to make things simpler and faster for the solar install. Maybe install the solar conduit to the roof now.
                We all love solar here, but depending on where the OP is, both geographically and with respect to solar design sophistication, active solar such as PV may not be the most cost effective measure to take and so not the first consideration, or maybe not a consideration at all depending on budget if cost effectiveness is the primary design consideration (after safety).

                I've designed and modified designs for cold, cloudy climates in the NE U.S. and designed for hot desert SW U.S. In one area (SW desert), solar load tempering via building envelope design mods/measures appropriate to the area followed by PV can be a no brainer. That's a lot, but not all of what Title 24 is all about. I was going t become a Title 24 auditor when I did my desert solar magnum opus, but the design stopped after plan/design for reasons unrelated to design. In the other area - Buffalo, NY - active solar can amount to brainlessly throwing inappropriate technology at building and HVAC design, and high mass designs with very high insulation and envelope sealing measures are more appropriate and much more cost effective than active solar. I'd also suggest most areas are between those two climate types meaning some knowledge of area appropriate design is called for.

                Not that it means much, but my experience w/ architects is mostly that they fall into two categories: One category thinks solar design is useless but will gladly and equally ignorantly slap/bolt poorly designed PV systems on their designs if a client insists and pays enough $$. The other type tend to be solar dreamers who feed their ego with what look like design nightmares that amount to technological trashing. There are a few in the middle, but practical and workable design experience tends to be lacking from what I've encountered, more so now than in the past.

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                • #9
                  Thank you all for the advise. Sounds like installing the conduit is a good idea as well as checking with the local building codes. Lots of other things in the thread to consider - thank you - David

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                  • #10
                    Depending on how big of an array you may install in the future, lot to be said for putting in a line side tap or a main panel with a 250 amp bus rating with 200 amp main breaker.

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                    • #11
                      Try to figure out how many panels you might install later and where you will put them. Then make sure plumbing vent pipes aren't in that space and aren't casting shadows across the panels. The conduit and planning for a breaker in your panel are both great suggestions.
                      Sunny Boy 7.7
                      30 Hyundai 290RG

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                      • #12
                        Most builders build to meet local building code...not exceed it. They do this not because they are bad builders, but to keep costs down. Generally customers are not willing to spend the additional money to make a more efficient home. If you plan to be in the home for a long time and are willing to take the long view by adding solar at some point, take the long view and spend the extra money on building a more efficient home from the beginning. It may push back the date on when you can afford to add solar, but it will be worth it.

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                        • #13
                          Originally posted by BoloMKXXVIII View Post
                          Most builders build to meet local building code...not exceed it. They do this not because they are bad builders, but to keep costs down. ....
                          I understand there will be costs and I agree with your general statement, especially the part about energy efficiency. This is not a spec home but rather a custom home and the owner is the one that posed the question.
                          Some markets are different. I used to live in a small expensive beach town in California. Several builders I knew were putting solar standoffs on the flat roofs of their million dollar spec homes because it allowed them to offer solar as an upgrade. With flat roofs (horizontal in JPM terminology) mounting standoffs before putting down the roofing is more cost effective than retrofitting standoffs. In essence they gambled on the cost of standoffs in order to offer a more profitable upsell opportunity.
                          Last edited by Ampster; 07-24-2019, 12:30 PM.

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