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  • Battery Backup for a Grid-Tied system

    I have a grid ties system based on solaredge optimizers and inverters with solarworld panels. 21 280w modules connected to SE6000 and 14 280w modules connected to an SE3800
    I would like to add battery backup and generator backup.
    Can I still take advantage of existing inverters. E.g. let them convert to 240V, just 'fool' them into thinking they're converted to the grid to continue producing (e.g. disconnect the main breaker).
    Outside of regulations. Help me understand the best way to proceed.

    Thanks,


  • #2
    Originally posted by NetComrade View Post
    I would like to add battery backup and generator backup.
    That's pretty easy - just buy a generator. I have had good luck with the Honda EU2000i for small loads. You may want a transfer switch as well to transfer your house loads to the generator.

    If you want to add a battery backup then you can either buy a dedicated UPS and switch the input between grid and generator, or build it out of pieces. For example, an Outback FX inverter plus a battery bank plus the usual protection/wiring devices.
    Can I still take advantage of existing inverters. E.g. let them convert to 240V, just 'fool' them into thinking they're converted to the grid to continue producing (e.g. disconnect the main breaker).
    No. Your only option there is something like the SMA Secure Power option; you could then use the 120VAC to feed your UPS. But it will not produce full power - it maxes out at 2000 watts.

    Comment


    • #3
      The software and sensors in the inverters are desigened to prevent what you want to do, sadly. Seems a shame to let the panels sit idle in the sun.
      The easiest way is to install a Generator Transfer Switch, and use a modest sized generator to keep the fridge going, lights and a radio.
      Adding batteries means charge controllers, more switches lots of batteries and a new Bi-Modal (also called Hybrid) inverter. And you get to replace batteries every 5-8 years, just because,
      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


      • #4
        I will second jflorey2's answer to the part about fooling your existing inverters into thinking the grid is still working. Unfortunately the answer is NO.

        You need a different type of inverter that will redirect the energy from your panels to a battery charging system which can then be used for your loads. The solaredge equipment you have can't do that.

        Comment


        • #5
          I thought of using a very small battery bank, to last let's say 30m worth of energy to give enough time to start the generator.

          Comment


          • #6
            Originally posted by NetComrade View Post
            I thought of using a very small battery bank, to last let's say 30m worth of energy to give enough time to start the generator.
            I am sure you can build a small UPS system that will carry you through a power outage until the gen set starts up. Based on cost I would charge it back up from the grid or from the generator instead of using the solar panel system. The cost of that type of charger probably would not pay for itself unless you get a lot of power outages.

            Comment


            • #7
              ok, thanks.. sounds the only other route (especially if I want to maintain remote monitoring of solaredge) is to install a 3rd hybrid inverter and tap into the 400V+ DC lines coming off the roof.

              The other route it to swap a solaredge with a one that supports the Tesla battery, but seems like that never really shipped.

              Comment


              • #8
                Originally posted by NetComrade View Post
                ok, thanks.. sounds the only other route (especially if I want to maintain remote monitoring of solaredge) is to install a 3rd hybrid inverter and tap into the 400V+ DC lines coming off the roof.
                I don't understand what you mean by "Third"
                you have only one inverter now the SE3800.
                ​you can AC couple with a bimodal inverter like from OutBack power, but trying to "tap" into the DC bus on the SolarEdge network is not a good idea and not likely to work anyway. You would void all warranties and have to come up with a charging solution from the 350-450V DC bus to your battery.

                Originally posted by NetComrade View Post
                The other route it to swap a solaredge with a one that supports the Tesla battery, but seems like that never really shipped.
                The SolarEdge SE7600 supports the powerwall V1
                any solarEdge inverter should support the powerwall V2

                or you could use the existing solaredge with an outback in an AC coupled fashion
                OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

                Comment


                • #9
                  I do have 2, Solaredge 3800 and SolarEdge 6000.
                  Teslas' you can't really buy, but good to know any SolarEdge inverter is compatible with powerwall 2.
                  "AC coupled" rings a bell... Will the mentioned Outback "fool" the SolarEdge they're connected to the grid?

                  I will also research what "bi-modal" means
                  Last edited by NetComrade; 11-18-2016, 02:59 PM.

                  Comment


                  • #10
                    You do not want batteries, just use a pad mounted whole house generator. When power goes out, your lkife goes on normally and you get to enjoy looking outside and watch your neighbors suffer. Use batteries and you and your wallet will be the one suffering.
                    MSEE, PE

                    Comment


                    • #11
                      Originally posted by NetComrade View Post
                      ok, thanks.. sounds the only other route (especially if I want to maintain remote monitoring of solaredge) is to install a 3rd hybrid inverter and tap into the 400V+ DC lines coming off the roof.

                      The other route it to swap a solaredge with a one that supports the Tesla battery, but seems like that never really shipped.
                      And probably won't for a while since they just voted on the merger. The focus will be somewhere else then a home battery system for a while.

                      On the flip side I just read an article about a company introduce something call the Totem. Looks cool and is much bigger then the PowerWall 2. No price yet

                      Comment


                      • #12
                        Originally posted by NetComrade View Post
                        I do have 2, Solaredge 3800 and SolarEdge 6000.
                        Why do you have so many small inverters on a single site?


                        Originally posted by NetComrade View Post
                        "AC coupled" rings a bell... Will the mentioned Outback "fool" the SolarEdge they're connected to the grid?

                        I will also research what "bi-modal" means

                        A bimodal inverter has batteries and can work on the grid and off the grid.
                        It will not "fool" the solarEdge inverters but will control them to keep the battery charged and provide power to an emergency panel.
                        take a look at the OutBack Radian inverters:
                        http://outbackpower.com/outback-prod...ategory_id=529
                        OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

                        Comment


                        • #13
                          Originally posted by NetComrade View Post
                          "AC coupled" rings a bell... Will the mentioned Outback "fool" the SolarEdge they're connected to the grid?
                          It can. But you don't want to - believe me. The hoops you'd have to jump through are many. You'd need another breaker panel, a few relays, a few inverters like the Radian, a large battery bank etc. (Around $12K total.) There's a reason almost no one does this.
                          Last edited by jflorey2; 11-18-2016, 05:30 PM.

                          Comment


                          • #14
                            Originally posted by ButchDeal View Post

                            Why do you have so many small inverters on a single site?

                            I was going to say because two different arrays are at a different pitch on my roof, but I am not sure it matters too much with optimizers.

                            Comment


                            • #15
                              Originally posted by NetComrade View Post

                              I was going to say because two different arrays are at a different pitch on my roof, but I am not sure it matters too much with optimizers.
                              It doesn't matter at all with solaredge optimizers
                              OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

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