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  • #16
    JPM

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    • #17
      JPM - again thanks for taking the time to help. I try. At 74, to be a bit tech savvy - but my kids would disagree. I am not familiar with programs you reference, but will check then out. I am leaving tonight on vacation but will be back on 19th. I may be able to access this forum while one but not sure.

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      • #18
        Originally posted by beowulf View Post
        JPM - again thanks for taking the time to help. I try. At 74, to be a bit tech savvy - but my kids would disagree. I am not familiar with programs you reference, but will check then out. I am leaving tonight on vacation but will be back on 19th. I may be able to access this forum while one but not sure.
        You're most welcome.

        I'm damn near as old as you. Think and do as you wish, and absolutely NOMB, but unless age related dementia has got hold of you, and not that it matters too much to anyone except me, I don't buy the old fart argument. That's always sounded and still sounds too much like a red herring to me. Anyone who can read this post can learn and run simple software that's intended for use by the great unwashed masses. Usually, the worst that can happen is things take a few milliseconds longer to sink in. Fortunately, and as some compensation maybe for me only, I've found age usually brings a bit of patience with it as some offset for any mental slowdown.

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        • #19
          Originally posted by beowulf View Post
          JPM
          Yes ? You called ?

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          • #20
            Originally posted by beowulf View Post
            JPM - thanks. I can't find all my notes re calculations I made, but the particular site did it this way: based on latitude of 37 (rounded up) it calculated the optimal Summer tilt to be about 13.2, and the optimal Winter tilt to be about 51, then it added those and divided by 2 to get to 31. Not sure that is how to do it - but will let the contractor figure it all out. I had not thought about the azimuth.
            A few notes.

            If you are net metered, then you are better off optimizing for sun collection in summer, since that's when you get the most energy. (= shallower)
            (Note that if you are completely off grid you are often better off optimizing for winter collection since that's when you will be short of energy - but looks like that's not an issue for you.)

            If you are on a time of use plan, and power is more expensive in the evening, it can be worth biasing the array towards the west.

            If there is a time of day where there are more or less clouds, it can be worth biasing the array in the direction you get the most sun. (Here by the coast in San Diego that means more west.)

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            • #21
              Originally posted by J.P.M.
              I'm damn near as old as you.
              I have you both beat, the Battle of Midway marks my beginning. Bruce Roe

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              • #22
                Originally posted by jflorey2 View Post

                A few notes.

                If you are net metered, then you are better off optimizing for sun collection in summer, since that's when you get the most energy. (= shallower)
                (Note that if you are completely off grid you are often better off optimizing for winter collection since that's when you will be short of energy - but looks like that's not an issue for you.)

                If you are on a time of use plan, and power is more expensive in the evening, it can be worth biasing the array towards the west.

                If there is a time of day where there are more or less clouds, it can be worth biasing the array in the direction you get the most sun. (Here by the coast in San Diego that means more west.)
                Jeff: To your note of a shallower tilt, I'd respectfully suggest that with all the relatively easy to use and reasonably reliable models available, it's too easy to get a better number for a tilt than by simply saying (and perhaps somewhat intuitively) summer is sunnier so tilt lower. While probably not a bad suggestion, maybe /maybe not as dichotomous is possible. Example, for me (only) optimum is 29 deg. tilt, 192 deg. az. "Lower" ? Maybe. Lower than what ?

                Some offerings/mental spoor. Take them for what they may be worth.

                For several reasons, what to do with an array orientation vis'-a-vis' what to do about present and/or future T.O.U. tariff schemes is one of those gray areas.

                1.) If it's thought that one will stay on tiered rates (as I understand I can do, at least as things are written now, even though it will take some positive election by me with my active notification of such an election to SDG & E), then an orientation that maximizes annual PV generation is probably desirable.

                2.)To the degree that future mandates for T.O.U of some sort will be unavoidably mandated by the POCO, a user may want to take their best shot at guessing what any such future T.O.U. tariffs and schedules may look like and then investigate how different array orientations might affect billing.

                3.) If, for whatever reason, a T.O.U. billing tariff is a forgone conclusion for a user, and assuming the times associated with various rates for such a tariff will not change drastically in at least the near to mid term - a few years maybe, it is sometimes possible to think of a PV system as a revenue generator (somewhat but not entirely separate from it being a power generator), and then find an array orientation that maximizes that revenue that can and will only be user as annual bill offset. This works best for tariffs that are purely T.O.U. (such as SDG & E's schedule DR-SES for new - non grandfathered customersd) and do not have a tier schedule incorporated into them. In such cases of no tiered rate incorporated and strictly a T.O.U. schedule, if a kWh is generated at a certain hour of 8,760 hrs. in a year, by the tariff schedule it's working to, it makes no difference whether or not a kWh is used on site, or sent to the grid - the value is the same. That kWh will have a certain value, that value being what the POCO per kWh charge is for that specific hour of the year.

                4.) If the tariff scenario described in # 3 above is applicable, then the following may be helpful:
                - Run PVWatts and get the hourly output on a spredsheet
                - Get the POCO rates and times of those rates from the schedule used onto the same spreadsheet. This is a bit of a PITA, but not as bad as it may at first appear. Most 168 hr. weeks can be copied for summer and winter schedules. Just don't forget the D.S.T. adjustment. PVWatts stays on std. time. Most POCO schedules use civil time and use D.S.T.
                - Multiply the hourly generation by the hourly rate for hourly revenue.
                - Sum all hours for an annual bill offset.

                5.) Doing # 4 above and somewhat parochially, for inland San Diego Co., at this time and under DR-SES, the most bill offset per installed STC kW is at an orientation of about 203 deg. and about a 30 deg. tilt. That amount is ~ $421/installed ST kW. So a 5 kW array will produce ~ $421 * 5 = $2,105/*yr. that can be used to offset a bill. Three interesting findings, among many:
                - A 20 deg. tilt, 180 deg. az. will offset about $412 /installed STC kW, so not much less than the optimum.
                - Before the last rate change of 09/07/2018, the same orientations would offset $462 and $452/installed STC kW respectively, mostly because the peak summer hourly rate went down.
                - A west (270 deg.) azimuth is a loser. At a common 20 deg. roof slope, a 270 deg. az. array generates $370/yr. offset per installed STC kW or about 10 % less than a south or mostly south facing azimuth.

                6.) Given the degree of uncertainly about future billing schemes and the future of NEM in general, if I was doing a new PV install today, I'd probably face an array as southerly as possible, going for max. generation, maybe a bit to the west if given a choice or mandate. Reason: Until I get way off south, annual billing offsets under T.O.U. are not that sensitive to orientation until I get past a tilt greater than, say, 30 deg. But I'd caution that's only for my general location.

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                • #23
                  Originally posted by bcroe View Post

                  I have you both beat, the Battle of Midway marks my beginning. Bruce Roe
                  Geriatricians rule !

                  What ? Speak up and quit mumbling !

                  Comment


                  • #24
                    Back from vacation and with an Internet connection again. I have a bit more information after emailing one of the contractors a list of questions. I learned that they suggest a 19 degree fixed tilt (tho no explanation yet for why they get to that tilt - that does not seem correct based on my layman's research but I am no expert) and I learned that the fencing and weed barrier and gravel for the 20 x 60 area they say they will need for a ground mount is at our cost (I figured that would be the case and okay with that - we have to fence it due to cattle and not wanting to deal with weeds underneath - but this adds an expense not incurred with a roof system).

                    But a few things will require some more discussion: One - they say a panel upgrade will add to the cost - $1,600 if needed and they report that it is needed in about 5% of their installations, and Two - the full payment for the system has to be paid when the material is "delivered". I assumed payments would be made as things progressed, e.g., some on delivery, some when activated and signed off by the County and utility - that is a non-starter for us. And Three and finally, I think they are requiring a payment of $1,000 prior to a site inspection. I prefer to have the site inspection first so that their bid will be accurate based on the reality of the site, so that we will both know what we are dealing with going forward. I am emailing today for clarifications and to arrange a site inspection to determine if a panel upgrade is needed, and why, etc.

                    Hopefully, a panel upgrade will not be necessary. I will not, however, agree to pay the full balance upon delivery of the panels - I will insist on some reserve to be paid only upon activation and sign off by County and utility - I assume they will be flexible on this as company seems reputable and they have been candid and responsive.

                    The overall cost seems reasonable based on what I have learned so far (Panasonic panels, SolarEdge optimizers, SolarEdge Inverter, 9.9kw) . I just need to work through the details.

                    And again, thank you for all the information - much appreciated as I work through this.

                    Comment


                    • #25
                      Originally posted by beowulf View Post
                      Back from vacation and with an Internet connection again. I have a bit more information after emailing one of the contractors a list of questions. I learned that they suggest a 19 degree fixed tilt (tho no explanation yet for why they get to that tilt - that does not seem correct based on my layman's research but I am no expert) and I learned that the fencing and weed barrier and gravel for the 20 x 60 area they say they will need for a ground mount is at our cost (I figured that would be the case and okay with that - we have to fence it due to cattle and not wanting to deal with weeds underneath - but this adds an expense not incurred with a roof system).

                      But a few things will require some more discussion: One - they say a panel upgrade will add to the cost - $1,600 if needed and they report that it is needed in about 5% of their installations, and Two - the full payment for the system has to be paid when the material is "delivered". I assumed payments would be made as things progressed, e.g., some on delivery, some when activated and signed off by the County and utility - that is a non-starter for us. And Three and finally, I think they are requiring a payment of $1,000 prior to a site inspection. I prefer to have the site inspection first so that their bid will be accurate based on the reality of the site, so that we will both know what we are dealing with going forward. I am emailing today for clarifications and to arrange a site inspection to determine if a panel upgrade is needed, and why, etc.

                      Hopefully, a panel upgrade will not be necessary. I will not, however, agree to pay the full balance upon delivery of the panels - I will insist on some reserve to be paid only upon activation and sign off by County and utility - I assume they will be flexible on this as company seems reputable and they have been candid and responsive.

                      The overall cost seems reasonable based on what I have learned so far (Panasonic panels, SolarEdge optimizers, SolarEdge Inverter, 9.9kw) . I just need to work through the details.

                      And again, thank you for all the information - much appreciated as I work through this.
                      Question: What do you think or what does some vendor claim will be the benefit of a panel upgrade ? Believe me, in spite of what they may be telling you, for that same application, location, and array orientation it will not be improved annual output.

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                      • #26
                        Power / breaker panel?
                        2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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                        • #27
                          Originally posted by J.P.M. View Post

                          Question: What do you think or what does some vendor claim will be the benefit of a panel upgrade ? Believe me, in spite of what they may be telling you, for that same application, location, and array orientation it will not be improved annual output.
                          JPM - I just this minute got off the phone with the vendor. A major part of the discussion was a panel upgrade cost or even the issue of a possible transformer or wire size drop from the transformer, vacant breaker spaces in the panel and so on.

                          With those uncertainties in mind - our current disagreement is over a nonrefundable $1,000 deposit to be paid prior to a site inspection. If we go forward the $1k is applied to the cost, if we do not, it is not refundable. I indicated that I was fine with going forward with everything as now understood (cost, panel specs, and so on) but did not want to pay $1k prior to a site inspection which might turn up things that changed the terms, cost, and more in ways that would not be acceptable. I told them we are prepared to go forward right away with a site inspection, and then would expect to learn of any changes, cost increases etc. and if all that was still acceptable we would go forward. This part is not yet agreed to - I told them I would send acceptable contract terms re that for them to consider - I guess we will or will not reach an agreement. Is it common to pay a non-refundable deposit prior to a site inspection where you can learn of issues in advance of contracting??

                          Re the payment of all the money upon delivery of equipment, they are agreeable to having a portion held back until it is fully installed, but not until utility signs off as that is out of their control and in the case of a two meter set up and NEM and aggregation, that can apparently take a very long time. Still discussing this but apparently solvable.

                          So re the $1600 cost if a panel upgrade required - now stated to be $1800 (in this call), it is a fixed cost I would have to pay if the site inspection determined a panel upgrade was needed. I understand the panel needs to be suitable, and there would be a cost associated with that, but I want to know all that, and if the transformer will work out, and if the wire size in the drop from the transformer are okay before I sign the agreement - if transformer and wire issues then much more costs. . . I just want to know the total cost and alternatives available.

                          I think I may need to have to re-contact other vendors to see if they will do a site inspection before bidding so I will know what we are looking at. I like the vendor I have been dealing with and we have both been very candid with each other but issues remain.



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                          • #28
                            Originally posted by littleharbor View Post
                            Power / breaker panel?
                            I guess both are in play. He asked about vacant breaker space. Then later mentioned the transformer and wire size dropping from the transformer. I just want to know total commitment going in.

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                            • #29
                              Originally posted by beowulf View Post

                              JPM - I just this minute got off the phone with the vendor. A major part of the discussion was a panel upgrade cost or even the issue of a possible transformer or wire size drop from the transformer, vacant breaker spaces in the panel and so on.

                              With those uncertainties in mind - our current disagreement is over a nonrefundable $1,000 deposit to be paid prior to a site inspection. If we go forward the $1k is applied to the cost, if we do not, it is not refundable. I indicated that I was fine with going forward with everything as now understood (cost, panel specs, and so on) but did not want to pay $1k prior to a site inspection which might turn up things that changed the terms, cost, and more in ways that would not be acceptable. I told them we are prepared to go forward right away with a site inspection, and then would expect to learn of any changes, cost increases etc. and if all that was still acceptable we would go forward. This part is not yet agreed to - I told them I would send acceptable contract terms re that for them to consider - I guess we will or will not reach an agreement. Is it common to pay a non-refundable deposit prior to a site inspection where you can learn of issues in advance of contracting??

                              Re the payment of all the money upon delivery of equipment, they are agreeable to having a portion held back until it is fully installed, but not until utility signs off as that is out of their control and in the case of a two meter set up and NEM and aggregation, that can apparently take a very long time. Still discussing this but apparently solvable.

                              So re the $1600 cost if a panel upgrade required - now stated to be $1800 (in this call), it is a fixed cost I would have to pay if the site inspection determined a panel upgrade was needed. I understand the panel needs to be suitable, and there would be a cost associated with that, but I want to know all that, and if the transformer will work out, and if the wire size in the drop from the transformer are okay before I sign the agreement - if transformer and wire issues then much more costs. . . I just want to know the total cost and alternatives available.

                              I think I may need to have to re-contact other vendors to see if they will do a site inspection before bidding so I will know what we are looking at. I like the vendor I have been dealing with and we have both been very candid with each other but issues remain.


                              That's an electrical panel upgrade and not a solar panel upgrade, right ? Just checking.

                              I don't know how far along you may be in the contract process. If still in the proposal stage(s), and someone wanted $1K for a site visit, that sounds like a separate contract to me in which case the dep. (in CA) can be no more than 10 % of the contract price = $100. I'm not sure what "site inspection" means in your context.


                              Once you have a signed contract, it should include all terms and conditions and a payment schedule that's agreeable by mutual consent can be set, but to my limited experience, the initial amount with no deliverables is limited to no more than that $1,000 or 10% of the contract price.

                              If it was me, and that $1,000 was for a site inspection, I'd get a second opinion from a different established electrical contractor and ask if that 2d contractor could do the work for, say, $1,200, and maybe negotiate some, and then have the panel upgrade and other non PV array work done by that 2d contractor. Enough of this B.S. screwing around. But that's just me.

                              FWIW, As for any hold back of final payment pending completion, that's often a negotiable point. I had a stipulation added to my contract that if the PV array was not ready and tested for a day's run by a certain date as loosely allowed by my POCO (8 weeks after contract signing for me), the final 10 % of the contract would be held back, and also the vendor would pickup my entire electric bill from scheduled completion until such testing was completed. The vendor beat the project schedule by 2 days. That holdback had no bearing on the POCO's possible foot dragging as that was out of the vendor's and my control. Maybe or because of making myself a PITA to SDG & E about rate history and other matters over the prior 5 yrs. or so, I think maybe they (SDG & E) gave the squeaky wheel (me) some pre-grease. SDG & E issued their PTO ( Permission to Operate) 5 days later.

                              Sounds like you know it's all nothing personal - just business.
                              Last edited by J.P.M.; 10-20-2018, 11:23 AM.

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                              • #30
                                JPM,
                                I advised the vendor that wanted the $1k non refundable deposit before a site visit/inspection that it was a non-starter, and that other vendors would visit and assess everything before providing a proposal and they did not require a deposit. So, I scheduled a site visit/inspection with another vendor this morning. They just left. I learned a whole lot in that visit (without spending $1k on a non-refundable deposit): 1) available ground mount locations are options but not that feasible due to trenching and distance and disturbing a patio, 2) two other buildings which appeared viable from a satellite shot are really not great due to shading, 3) it seems I will not need an electric panel upgrade (have 200 amp service with breaker space available), and 4) the location I preferred all along is the best location and totally doable (the garage/gym building - facing South and never shaded). They are writing it up with Panasonic panels and SolarEdge inverter and optimizers and it seems at this stage the cost will come in at the right point when compared to other non-site-visit bids. One uncertainty is the run to the main panel from the garage/gym building - their engineer will determine if the 2" existing conduit from the main panel to the 100 amp panel in the garage will accommodate the wiring they need to run there. If not, there will need to be some trenching (which I can do) and some additional cost re the wire - all okay and understandable.

                                So, things moving along and I learn more every day. Thanks again - your input has been very, very helpful.

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