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Problem installing PV system with battery and common generator

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  • Problem installing PV system with battery and common generator

    I live in a complex with 6 townhouses that share a common backup generator. After last year's hurricane season when our generator failed and we didn't have power for 3 months, I decided to get solar panels and settled on a 9 kW sunpower (360w panels) system with 2 LG RESU-10H batteries and a SolarEdge (storedge) inverter. The installer put the panels on the roof and wired the inverter but we ran into a serious problem because there is no switch to turn the generator off and on from my unit so I was told there was serious risk of power backfeed because the system would confuse the generator power as grid power which could damage both the inverter and generator (and SolarEdge said this set up would void the warranty).

    I'm wondering if anyone here has any advice or a solution? The HOA will not approve me getting a communications cable to the generator which is required to set up a transfer switch because that would involve digging up the driveway. The only other solution being posed now is switching to an expensive Sonnen battery and using the panels' micro inverters but the design hasn't yet been approved by Sonnen. I would also be out the money on the SolarEdge inverter and optimizers.

    Any new ideas would be greatly appreciated.




  • #2
    The Solar Edge system uses optimizers, not microinverters. Will that make a difference?
    2.2kw Suntech mono, Classic 200, NEW Trace SW4024

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    • #3
      Sonnen will not deal with the situation any better
      OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

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      • #4
        Use a manual transfer switch ?
        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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        • #5
          Would the HOA approve something wireless? That would definitely be doable. If the generator is quality, it could trick any inverter into thinking it is the grid, Sonnen (Outback Radian) included. From my experience, Sonnen will connect to equipment that Solaredge will not. (Generator running at 63hz)

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          • #6
            Originally posted by Ben25 View Post
            Would the HOA approve something wireless? That would definitely be doable. If the generator is quality, it could trick any inverter into thinking it is the grid, Sonnen (Outback Radian) included. From my experience, Sonnen will connect to equipment that Solaredge will not. (Generator running at 63hz)
            There is no portable generator that can "trick" an inverter to think the grid is up and to fully produce power.

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            • #7
              Originally posted by Ben25 View Post
              Would the HOA approve something wireless? That would definitely be doable. If the generator is quality, it could trick any inverter into thinking it is the grid, Sonnen (Outback Radian) included. From my experience, Sonnen will connect to equipment that Solaredge will not. (Generator running at 63hz)
              Sonnen is just repackaged OutBack inverters.

              They are not tricked by the generator to think the grid is up, that would be very bad.
              Outback can connect to and work with a generator on a dedicated port though, which is very different from thinking the grid is up. If the Outback inverter though the grid was up it would (in a grid tie configuration) back feed the solar power which would not be very good for the generator.
              OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

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              • #8
                Ah, ok. I've only worked with Sonnen with a generator on the generator input. (Off grid, that's been a challange!)

                Originally posted by ButchDeal View Post

                Sonnen is just repackaged OutBack inverters.

                They are not tricked by the generator to think the grid is up, that would be very bad.
                Outback can connect to and work with a generator on a dedicated port though, which is very different from thinking the grid is up. If the Outback inverter though the grid was up it would (in a grid tie configuration) back feed the solar power which would not be very good for the generator.

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                • #9
                  Sounded like the OP had a large generator that powered the entire complex. If it is tested and proven that his StorEdge will not power up off the generator, problem solved.

                  Originally posted by SunEagle View Post

                  There is no portable generator that can "trick" an inverter to think the grid is up and to fully produce power.

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                  • #10
                    Originally posted by Ben25 View Post
                    Sounded like the OP had a large generator that powered the entire complex. If it is tested and proven that his StorEdge will not power up off the generator, problem solved.


                    The only generator that I know will trick an inverter belongs to the POCO at one of their power generating stations. Even a 2MW high voltage generator will not provide the correct information to make a solar inverter work.

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                    • #11
                      Originally posted by SunEagle View Post

                      The only generator that I know will trick an inverter belongs to the POCO at one of their power generating stations. Even a 2MW high voltage generator will not provide the correct information to make a solar inverter work.
                      What is it that is different from the power generated from a "prime power" generator that keeps it from appearing the same as utility power?

                      I worked in IT for many years in operations that depended on generator backup and never had any gear that had trouble with it. It surprises me that an inverter would have trouble.....

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                      • #12
                        Originally posted by PNW_Steve View Post
                        What is it that is different from the power generated from a "prime power"
                        generator that keeps it from appearing the same as utility power?

                        I worked in IT for many years in operations that depended on generator backup and never had any gear
                        that had trouble with it. It surprises me that an inverter would have trouble.....
                        Most loads are not so fussy about the backup power they run on. But an inverter is not a load, it is a
                        source. To avoid dangerous situations (delivering power when the prime power is somehow
                        disconnected), the inverter is very fussy about frequency, and probably is programmed to make tests
                        of the line impedance (which will be lower with prime power connected). Failing, it will not run.
                        Bruce Roe

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                        • #13
                          Originally posted by PNW_Steve View Post

                          What is it that is different from the power generated from a "prime power" generator that keeps it from appearing the same as utility power?

                          I worked in IT for many years in operations that depended on generator backup and never had any gear that had trouble with it. It surprises me that an inverter would have trouble.....
                          The solar inverter is looking for a number of electrical properties that it will recognize as "the grid". These include voltage, frequency, impedance along with possibly phase shift. The POCO and it's miles of distribution wiring provides those values for the inverter to recognize so it will work. Otherwise the "anti-island" protection software in the inverter will tell it to shut down if it thinks "the grid" is gone.

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                          • #14
                            Originally posted by PNW_Steve View Post

                            What is it that is different from the power generated from a "prime power" generator that keeps it from appearing the same as utility power?

                            I worked in IT for many years in operations that depended on generator backup and never had any gear that had trouble with it. It surprises me that an inverter would have trouble.....
                            then it really should not surprise you and the inverters do NOT have trouble. It is a safety system that is built in to keep the magic smoke in all the boxes.

                            OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

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                            • #15
                              Originally posted by SunEagle View Post

                              The solar inverter is looking for a number of electrical properties that it will recognize as "the grid". These include voltage, frequency, impedance along with possibly phase shift. The POCO and it's miles of distribution wiring provides those values for the inverter to recognize so it will work. Otherwise the "anti-island" protection software in the inverter will tell it to shut down if it thinks "the grid" is gone.
                              Learning something new everyday

                              My experience with inverters has been off grid or grid backup. Never any grid connected. I had no idea they went as phase shift and impedance.

                              Thank you for sharing.

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