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Conflicting Solar Layouts from Vendors and Enphase vs SolarEdge

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  • Conflicting Solar Layouts from Vendors and Enphase vs SolarEdge

    Hi all,

    I've gotten a lot of quotes from recommended vendors and with my top 3 I'm getting conflicting advice on the layout along with Enphase vs SolarEdge.

    I asked the vendors to keep the solar panels off of the front of the front unit. Vendor A shows a very compact layout, Vendor B shows a Tetris layout, and Vendor C says they need to use the North (up in the pic) side of the back unit using tilt racks to get them all on . Why are they all so different? Who's doing a bad job? Vendor C says that there's no way to do the Tetris layout with SolarEdge which is what I was asking for originally. Is that true?

    I was asking to go with SolarEdge since the reading I've done online seemed to show that in tests side by side PV systems the SolarEdge out produced the Enphase. And I was hearing that SolarEdge is cheaper. Vendor C disputes this and says with 330W panels there will be no clipping so they will produce the same. Vendor C is also offering the Enphase at the same price he quoted me for SolarEdge. What are your guys thoughts?

    Thank you!

    Vendor A
    Vendor A Layout.JPG

    Vendor B (Tetris)
    Vendor B Layout.png

    Vendor C
    Vendor C Layout.JPG

  • #2
    north layouts, with wind sail racking, are not looked favorably by myself.

    do you have any shade , at any season, on your roof ??
    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

    Comment


    • #3
      My first question is, have these companies actually come out and measured your roof, or are they working off of satellite images? There's a big push to avoid taking measurements, but satellite imagery isn't all that accurate, and could lead to the differences in A and B.
      Vendor C doesn't know what they are doing, and I would avoid them. You don't want panels on the north side, and there is nothing stopping you from using SolarEdge on the Tetris layout. It's not ideal, but it can be done. Enphase would probably be easier.

      If A and B have not actually gotten on the roof, I would insist they do it and then provide an updated quote. Things aren't always as they seem when you get on the roof, and it could change their plans drastically.

      The other thing I notice between A and B is that B is observing the fire code requirement of a 3' setback from the ridge. A doesn't seem to be, which isn't surprising. Typically with a hip roof, most fire departments will grant a variance and allow you to mount panels up to the ridge on one side, as long as they have full access on the opposite side.

      Bottom line: The layout of A looks the best, but I would want them to confirm with hard measurements that the layout is possible.

      Comment


      • #4
        Vendor C is full of S*&t with most of their answers.

        Vendor A seems to have ignored the setbacks on the larger south facing roof

        Vendor B could likely do a better job of layout and I would highly suggest an effort to move a few of the obstructions on the south facing roof and main west facing roofs to allow a simpler layout.

        What were the rest of the equipment that vendor A and B offered?
        I would completely ignore Vendor C as incompetent. Not only is everything they told you BS, but that has got to be the dumbest layout I have ever seen, worthy of a wall of shame.
        OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

        Comment


        • #5
          Originally posted by emartin00 View Post

          The other thing I notice between A and B is that B is observing the fire code requirement of a 3' setback from the ridge. A doesn't seem to be, which isn't surprising. Typically with a hip roof, most fire departments will grant a variance and allow you to mount panels up to the ridge on one side, as long as they have full access on the opposite side.
          you can get a variance for one HIP not the ridge itself. You can only go up to one hip if there are no modules on the opposite hip adjacent face. technically it is not a variance though as it is allowed in the rules but you could request a variance for anything though many fire marshals are not willing to make many these days. Here is a good example of the most common rules showing the hip/valley exceptions: https://www.cityofamericancanyon.org...ument?id=15614

          I highly question A's layout on the south roof.

          As for remote images being inaccurate, that is not always the case. Often the design is done based on LiDAR which is very very accurate and just overlaid on the imagery for reference.

          All three seem to be done off hand though with exception of B might have gotten the roof edges automatically.

          Oddly C (which seems incompetent) is the only one to draw in trees but they are completely irrelevant trees shading only part of the front roof which is not to be used.
          Last edited by ButchDeal; 07-02-2019, 08:38 AM.
          OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

          Comment


          • #6
            Originally posted by Mike90250 View Post
            north layouts, with wind sail racking, are not looked favorably by myself.

            do you have any shade , at any season, on your roof ??
            No shade on the roof in any season that I know of. There are no trees around but next door on the south side is a two story vs my one story. Vendor A used some device to measure and said there would be no shade.

            I'm pretty sure vendor A did take measurements. I'm going to confirm with him that he did and ask about the 3ft ridge setback and let you guys know.
            Last edited by crazycorkey; 07-02-2019, 11:41 AM.

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            • #7
              Also Vendor B and C haven't been on site.

              Thank you all for your input!

              Comment


              • #8
                Are you in California or another jurisdiction requiring 3 foot setbacks? Not all locations require, but California generally does.

                Vendors definitely need to get up on the roof and measure. Also keep in mind different panels (60/96 vs 72-cell, LG versus others) are slightly different sizes and shapes. So once the vendor actually measures, the exact panel make and model, together with the setback requirements and obstructions, will drive the layout. Both SE and Enphase give very similar productivity, both can have losses due to clipping if panels / inverters / optimizers are not sized well. Both provide rapid shutdown and MPPT so neither technology is "inherent;y better" per se. But both can perform sub-optimally if the system is poorly designed.

                This seems like a fairly large installation. Will your AHJ permit a line side tap (California usually does not for residential)? How many electric panels / meters do you currently have? Of what amperage? Should the two "dwellings" be split into separate smaller systems, rather than trying to combine across the two roofs?

                You haven't mentioned the DC STC size in kW of these proposals. How do production estimates (from the vendor, and from PVWatts, SE Site Designer, etc.) compare with your current usage? Will your PoCo permit an interconnect agreement for this size system? Is it residential?

                Panel orientation (portrait, landscape, mixture), nor even the panel itself (make, model , wattage (within the scope of the optimizer used)), has any bearing on the operation of the SE (or Enphase) solution per se. In the SE case, once the panel is above the starting voltage requirement of the optimizer' (8-12V typically) the buck/boost capability of the optimizer "tunes" the panel's output voltage such that all of the members of the string work together to optimize the DC string voltage for the inverter.

                Individual panel orientation then only has a small bearing if shade, sliding snow, angle of the sun, etc. play a significant role in how the bypass diodes on the panel are "tripped" (or not) in one configuration or another.

                For example, on horizontal roofs or ground mounts where one row of panels may at certain times of the day/year cast a shadow on the row behind. Since bypass diode strings usually run along the long axis of the panel, portrait orientations in these cases may be much less productive if aisle spacing is constrained.

                But in your case, for in plane roof mount, orientation doesn't really matter save potentially for the shadows cast by your dormers.
                Last edited by JSchnee21; 07-02-2019, 01:41 PM.

                Comment


                • #9
                  Originally posted by JSchnee21 View Post
                  Are you in California or another jurisdiction requiring 3 foot setbacks? Not all locations require, but California generally does.

                  ...

                  This seems like a fairly large installation. Will your AHJ permit a line side tap (California usually does not for residential)? How many electric panels / meters do you currently have? Of what amperage? Should the two "dwellings" be split into separate smaller systems, rather than trying to combine across the two roofs?

                  You haven't mentioned the DC STC size in kW of these proposals. How do production estimates (from the vendor, and from PVWatts, SE Site Designer, etc.) compare with your current usage? Will your PoCo permit an interconnect agreement for this size system? Is it residential?
                  ...
                  yes this installation is in San Diego, California.

                  I’m not sure what a line side tap is?

                  This is 4 unit residential. There are 4 meters located in the same panel on the northwest side of the west building. 100 amp each on a 400 amp line.

                  11.22kw. I’ve been requesting 34 330 watt Panasonic HIT panels since it seemed like the best option with the authorized installer warranty. I have asked about lower end panels but there wasn’t much of a price difference. I’m getting quotes at $2.62-$2.84/watt from these three vendors after looking at lots of others.
                  I haven’t verified production estimates from the vendors since they seemed similar and the source sizing data is a guess. I only have a few months of usage data on the 2 bedroom unit and full years on the three 1 bedrooms but they are switching to Short Term rentals so I imagine zero restraint on A/C and heater (heat pump) usage and poor energy conservation. I’m also adding a hot tub. The system is sized about 20% larger than current usage shows to account for these.

                  I was going to do NEM-ST Aggregation with one Solar system. I guess I could do one system for the front house and one system Aggregation for the back three units. I’m not sure what it would get me.
                  I do have some confusion about Aggregation. A different vendor told me that the true up is monthly so I’d really want to oversize the system for the summer months but emailing SDGE it sounds like a percentage of the generation is allocated to each unit based on the usage that month but if there was over generation it would still carry forward for each unit until the annual true up.

                  Comment


                  • #10
                    Talking with Vendor A, he did measure the roof and is adamant it will fit. He says it only needs 18 inches set back from the ridge since the opposing side is unused.

                    Comment


                    • #11
                      Originally posted by ButchDeal View Post
                      you could request a variance for anything though many fire marshals are not willing to make many these days.
                      FWIW, when I did my install my city's fire dept gave me a variance on going closer than 3' to the ridge. They asked if the array was going above the kitchen (it's not). And if the space under the array (the attic) was just open space (no walls between the two sides of the ridge. I'm assuming they were asking because if there's no wall separating the two sides then cutting a hole on north side of the ridge (for venting) is going to be largely the same as cutting that vent on the S side. And they looked at what the accessibility was (ie. where could they put a ladder to get up on that roof and walk to the ridge)

                      Originally posted by crazycorkey
                      There are 4 meters located in the same panel on the northwest side of the west building. 100 amp each on a 400 amp line.
                      Are all 4 meters under your single account?
                      I'm just wondering how you're going to do this with tenants. Do you just have utilities included in the rent? Or will you bill them yourself while you pay the electric company?

                      emailing SDGE it sounds like a percentage of the generation is allocated to each unit based on the usage that month but if there was over generation it would still carry forward for each unit until the annual true up.
                      I don't have SDGE, but probably it's like PGE. PGE is that the true-up is annual. So you pay the bill on your true-up date, and what you pay is dollars_consumed - dollars_generated (with basically a floor of $0).
                      So if you generated $800 of power throughout the year and sent it to them, and consumed $820 worth of power, you pay them $20. (and maybe also some per-month charge of $5/month or $10/month.)
                      If you consumed $780 worth of power, you pay $0, but you probably aren't getting that virtual $20 of production back. Most likely you'll still be a net consumer of kwh, but the kwh's that you sold were worth more than the ones you bought. They won't pay you in that case. But if you are actually producing more kwh than you consume you might get paid a tiny amount per kwh (like $0.04/kwh payout for net production vs. the $0.15/kwh that is the retail rate people pay as consumers)
                      I think that is what you will see for SDGE, but you should absolutely get your answer from SDGE themselves.

                      Comment


                      • #12
                        Originally posted by crazycorkey View Post
                        Talking with Vendor A, he did measure the roof and is adamant it will fit. He says it only needs 18 inches set back from the ridge since the opposing side is unused.
                        If he's done other installs in San Diego, he would probably be familiar with what they'll accept there.

                        Comment


                        • #13
                          Originally posted by foo1bar View Post
                          Are all 4 meters under your single account?
                          I'm just wondering how you're going to do this with tenants. Do you just have utilities included in the rent? Or will you bill them yourself while you pay the electric company?
                          Im going to have to put them all in my name and I'm just going to increase the rent and include utilities.

                          If if I did NEM-V-ST I could leave them in a tenants name but I'd have to pay for a generation meter and I'm going to do short term rentals anyway.
                          https://www.sdge.com/sites/default/f...x_7-5-15_0.pdf

                          For SDGE with Aggregation you don't get any payout for surplus at annual true up.


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                          • #14
                            Originally posted by crazycorkey View Post

                            Im going to have to put them all in my name and I'm just going to increase the rent and include utilities.

                            If if I did NEM-V-ST I could leave them in a tenants name but I'd have to pay for a generation meter and I'm going to do short term rentals anyway.
                            https://www.sdge.com/sites/default/f...x_7-5-15_0.pdf

                            For SDGE with Aggregation you don't get any payout for surplus at annual true up.

                            I have had some experience with NEM aggregation with SCE and it has been underwhelming. I was never in a situation that I had to worry about any true up credits. SCE was hand calculating NEM Agg accounts and it delayed the bills by six months and then a got a whole bunch together. I do have a separate House meter so when I add more solar I may go to NEM-VNM where the excess solar gets allocated to my tenants on a percentage that I designate. I am also considering putting EV Cbarging Stations in the parking area for their use. The demographics of my tenants suggests that this would be of value to them. From time to time I have had as many as 20% of my tenants drive EVs.
                            On another note, if I interprete your comments to mean you are going to do short term vacation rentals like VRBO etc there may be planning department issues. At least that was my experience in a beach town up the coast in Hermosa Beach.
                            9 kW solar. Driving EVs since 2012

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