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    Anti-solar AHJ's

    We have one that claims to grant rebates, but to qualify the array has to have an azimuth between 180 and 270 degrees and tilt between 45 and 80 degrees. That's not a typo and they have not confused tilt with elevation. That means that virtually no residences will qualify for rooftop systems; in ten years of designing solar in Texas I have seen roof tilts of 45 degrees only a handful of times and more than 45 degrees exactly never.

    These are the same guys that require all PV systems to be interconnected on the line side of the customer's meter. Yes, the meter, not the service disco.

    #2
    I think these meters would allow such a connection:
    https://newenglandcleanenergy.com/en...ers-for-solar/
    At my age, I'm accustomed to restaurants asking me to pay in advance, but now my bank has started sending me their calendar one month at a time.

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      #3
      Isn't 30 degrees the ideal tilt for a fixed system? If I remember correctly, that's what we were setting them at in North Carolina when I did 1.35 Mwatts worth.

      Comment


        #4
        Originally posted by Coppersmith View Post
        Isn't 30 degrees the ideal tilt for a fixed system? If I remember correctly, that's what we were setting them at in North Carolina when I did 1.35 Mwatts worth.
        Yes, but that's not what they are going for. They did some research and found that PV arrays at between 180 and 270 degrees azimuth and between 45 and 80 degrees tilt will produce the most energy between 3PM and 7PM when their demand is the highest.

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          #5
          Originally posted by augie47 View Post
          I think these meters would allow such a connection:
          https://newenglandcleanenergy.com/en...ers-for-solar/
          They won't do single metering here, because the paynback PV is 1/3 the normal poco KW $$$

          ~RJ~

          Comment


            #6
            Originally posted by ggunn View Post
            Yes, but that's not what they are going for. They did some research and found that PV arrays at between 180 and 270 degrees azimuth and between 45 and 80 degrees tilt will produce the most energy between 3PM and 7PM when their demand is the highest.
            But that doesn't make any sense. One gets the feeling they've defined tilt for the vertical instead of the horizontal, opposite from everyone else.

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              #7
              Originally posted by Coppersmith View Post
              Isn't 30 degrees the ideal tilt for a fixed system? If I remember correctly, that's what we were setting them at in North Carolina when I did 1.35 Mwatts worth.
              Ideal tilt is basically latitude, perhaps adjusted for weather, but also on whether you want to adjust for economic considerations. For example if you have a rate schedule that pays back higher rates in summer, you'd want a shallower tilt. Or it might be more cost effective to squeeze more panels in the space you have at less than optimum tilt so they don't shade each other. Or if you are off grid you might want to maximize winter production. It all depends.

              Comment


                #8
                Originally posted by jaggedben View Post
                Ideal tilt is basically latitude, perhaps adjusted for weather, but also on whether you want to adjust for economic considerations. For example if you have a rate schedule that pays back higher rates in summer, you'd want a shallower tilt. Or it might be more cost effective to squeeze more panels in the space you have at less than optimum tilt so they don't shade each other. Or if you are off grid you might want to maximize winter production. It all depends.
                Actually for the nitpickers among us, ideal theoretical year round tilt is about 6-7 degrees less than latitude for most of the 48.

                https://www.solarpaneltilt.com/
                Ethan Brush - East West Electric. NY, WA. MA

                "You can't generalize"

                Comment


                  #9
                  Originally posted by jaggedben View Post
                  But that doesn't make any sense. One gets the feeling they've defined tilt for the vertical instead of the horizontal, opposite from everyone else.
                  That's what I thought initially as well, but we've exchanged several emails with their engineer, and he has stated unequivocally that 45 to 80 degrees off the horizontal is what they mean. The center of their "ideal" time window is 5PM in the summer months, not noon. He sent us demand curves and graphs from NREL to illustrate it. 45 to 80 degrees tilt and 180 to 270 degrees azimuth is what they mean.

                  Comment


                    #10
                    Originally posted by ggunn View Post
                    That's what I thought initially as well, but we've exchanged several emails with their engineer, and he has stated unequivocally that 45 to 80 degrees off the horizontal is what they mean. The center of their "ideal" time window is 5PM in the summer months, not noon. He sent us demand curves and graphs from NREL to illustrate it. 45 to 80 degrees tilt and 180 to 270 degrees azimuth is what they mean.
                    Yeah, but while 80 tilt at 270az might be a reasonable range for that, 80deg at 180az is totally not. So it still makes no sense at all. I think your subject line is more insightful.

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                      #11
                      Some calculations of PV system performance

                      Seems that the real world situation is far from the understanding of the AHJ. A PV system installed at a tilt of 25°, facing South, will provide more output, about 20% more, at 5pm in the summer than if the tilt was 45°. The higher the tilt the larger the difference. Results of calculations assuming Dallas solar data are attached.
                      Attached Files

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                        #12
                        Originally posted by BillK-AZ View Post
                        Seems that the real world situation is far from the understanding of the AHJ. A PV system installed at a tilt of 25°, facing South, will provide more output, about 20% more, at 5pm in the summer than if the tilt was 45°. The higher the tilt the larger the difference. Results of calculations assuming Dallas solar data are attached.
                        I know that, you know that, and even they know that. Please note that this azimuth and tilt requirement is for approval of their rebate, not for building PV in general; they are only rebating systems which they believe as much as possible match their demand curve in June - September from 3PM to 7PM. Customers are welcome to build systems with other orientations if they forego the rebate, which they will all do since the losses in production they would incur in building PV that fits the rebate requirements would be more than the rebate itself.

                        They sent me a graphic from NREL that shows what they are driving at.

                        Comment


                          #13
                          Originally posted by BillK-AZ View Post
                          Seems that the real world situation is far from the understanding of the AHJ. A PV system installed at a tilt of 25°, facing South, will provide more output, about 20% more, at 5pm in the summer than if the tilt was 45°. The higher the tilt the larger the difference. Results of calculations assuming Dallas solar data are attached.
                          How bout if its 45 at 270 (and not at 180)? I assume that will produce more than 25 at 180, at the time they want it, which is centered around 5 pm.

                          Comment


                            #14
                            If they set up the criteria that any single system has to match their curve, then possibly the 180 - 80 system does so ... while producing such negligible power as to be of no use meeting the demand. Again, I refer back to the subject line. They have set a goal that is either deliberately or incompetently anti-solar. The goal is definitely not to encourage solar or actually spend the rebate money.

                            Comment


                              #15
                              AHJ acting as Utility Manager?

                              I am a little confused. You mention AHJ. That generally refers to the electrical inspector who enforces the NEC and building codes for the governmental jurisdiction. The utility may have concerns about the time of day when the generation is optimal based on their daily and annual load profiles, but that is not the jurisdiction of the building code enforcement agency. The utility can use rates, rules and regulations as permitted to give price signals to PV installers but the utility generally cannot set a standard for tilt and orientation. This sounds like the code inspector is enforcing a standard that is not in a adopted code. Am I missing something?
                              e^(i pi) = -1

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