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  • GroundLoop
    Junior Member
    • May 2022
    • 2

    Grid tied Certasun system - options to use solar system when power grid goes down

    Just got our grid tied solar system installed from Certasun using Sunpower A-Series 410 panels. Keep hearing about future power grid interruptions, possibly some of them long term. Wondering what are the options if the grid goes down what can be done to "trick" the system into running. From the research I have done and what I know from my electrical experience (electrician after high school and been doing electrical side jobs for over 20 years) the goal would be to possibly put a transfer switch to disconnect the Certasun system form the grid and connect it to some type of 220v source (generator, voltage invertor) so the system thinks it is still connected to the grid. Would still need some type of battery storage for a buffer.

    Is there a commercial solution to this problem that can be purchased?
    13kv Certasun using Sunpower A-410 panels
  • solardreamer
    Solar Fanatic
    • May 2015
    • 446

    #2
    Yeah ... many options for home battery systems to address your situation ... Tesla Powerwall is the most popular.

    Comment

    • organic farmer
      Solar Fanatic
      • Dec 2013
      • 644

      #3
      You should ask Certasun.

      There will likely be an option built into the device that would allow for islanding.

      My inverter is a MagnaSine. It has an Aux input meant for a generator. We connect gird power to the Aux input, so our system views grid power as if it were a part-time generator.

      In our township grid power goes down frequently.




      4400w, Midnite Classic 150 charge-controller.

      Comment

      • azdave
        Moderator
        • Oct 2014
        • 761

        #4
        This is asked often and no. There is no way to trick a standard grid-tie inverter into operating when it does not see the grid. There are dozen of threads here where people ask the exact same question.

        Here is a recent related thread.

        I installed a 5kw, grid tie using a sunnyboy inverter, it has been up and working for about 2 years now. My question is: worse case scenario, we lose the grid, what hardware do I need to run well pump intermittently(240) and freezer? could I reconfigure my array to use an outback charge controller, and then maybe a midnite

        Dave W. Gilbert AZ
        6.63kW grid-tie owner

        Comment

        • Ampster
          Solar Fanatic
          • Jun 2017
          • 3649

          #5
          The concept is called AC coupling and it is what a Tesla Powerwall does to leverage GT inverters. Many but not all hybrid inverters come with that capability but I would not describe it as simple as to "trick" the GT inverter. It's a complex test that a GT inverter goes through to test for the presence of a grid. In addition the hybrid has to have complex programming and measurement and control systems in order to manage the output of a GT inverter that is designed to run connected to a grid that presents an infinite load to the GT inverter.
          9 kW solar, 42kWh LFP storage. EV owner since 2012

          Comment

          • SunEagle
            Super Moderator
            • Oct 2012
            • 15125

            #6
            Originally posted by Ampster
            The concept is called AC coupling and it is what a Tesla Powerwall does to leverage GT inverters. Many but not all hybrid inverters come with that capability but I would not describe it as simple as to "trick" the GT inverter. It's a complex test that a GT inverter goes through to test for the presence of a grid. In addition the hybrid has to have complex programming and measurement and control systems in order to manage the output of a GT inverter that is designed to run connected to a grid that presents an infinite load to the GT inverter.
            While a Powerwall may give someone that option it is still very expensive considering the amount of kWh it can provide daily. But the cost comparison is different based on where someone lives.

            As I have always said. DO the Math before you commit to opening the wallet.

            Comment

            • Ampster
              Solar Fanatic
              • Jun 2017
              • 3649

              #7
              Originally posted by SunEagle

              While a Powerwall may give someone that option it is still very expensive considering the amount of kWh it can provide daily. But the cost comparison is different based on where someone lives.

              As I have always said. DO the Math before you commit to opening the wallet.
              I agree the math and the local rates are important. Where Powerwalls and other battery based system are selling well is in high rate Time of Use environments where load shifting is where the bulk of the payback arises. Then backup just becomes another benefit not the main decision driver.
              9 kW solar, 42kWh LFP storage. EV owner since 2012

              Comment

              • solardreamer
                Solar Fanatic
                • May 2015
                • 446

                #8
                Originally posted by azdave
                This is asked often and no. There is no way to trick a standard grid-tie inverter into operating when it does not see the grid. There are dozen of threads here where people ask the exact same question.

                Here is a recent related thread.

                I installed a 5kw, grid tie using a sunnyboy inverter, it has been up and working for about 2 years now. My question is: worse case scenario, we lose the grid, what hardware do I need to run well pump intermittently(240) and freezer? could I reconfigure my array to use an outback charge controller, and then maybe a midnite
                Perhaps the mods can create a sticky thread for this often asked question ...

                Comment

                • SunEagle
                  Super Moderator
                  • Oct 2012
                  • 15125

                  #9
                  Originally posted by solardreamer

                  Perhaps the mods can create a sticky thread for this often asked question ...
                  We could but the issue is will those that are determined to make a solar GTI work without the grid actually read it.

                  Comment

                  • Ampster
                    Solar Fanatic
                    • Jun 2017
                    • 3649

                    #10
                    Originally posted by SunEagle

                    We could but the issue is will those that are determined to make a solar GTI work without the grid actually read it.
                    Darwin will take care of those people. How about the perspective of helping people, It sounds like a lot of work for you, Could one of the other Mods do it so you don't have to waste your time.
                    9 kW solar, 42kWh LFP storage. EV owner since 2012

                    Comment

                    • GroundLoop
                      Junior Member
                      • May 2022
                      • 2

                      #11
                      Originally posted by organic farmer
                      You should ask Certasun.

                      There will likely be an option built into the device that would allow for islanding.

                      I did ask that question when we were purchasing the system. Did not use the technical term 'islanding'. They told me the only option would be the Tesla battery system. Going to try again.

                      I did find this while looking up islanding https://palmetto.com/learning-center...anti-islanding
                      13kv Certasun using Sunpower A-410 panels

                      Comment

                      • SunEagle
                        Super Moderator
                        • Oct 2012
                        • 15125

                        #12
                        Originally posted by Ampster

                        Darwin will take care of those people. How about the perspective of helping people, It sounds like a lot of work for you, Could one of the other Mods do it so you don't have to waste your time.
                        I would prefer that all solar sellers provide that info at the time they are suggesting a system. Unfortunately some people either won't understand or will look for a way to "trick" the inverter to think there is a grid.

                        Comment

                        • Ampster
                          Solar Fanatic
                          • Jun 2017
                          • 3649

                          #13
                          Originally posted by GroundLoop

                          I did ask that question when we were purchasing the system. Did not use the technical term 'islanding'. They told me the only option would be the Tesla battery system. Going to try again.

                          ....
                          The Tesla Powerwall may be the only option they install. From what I have seen from other forums it may a cost effective solution unless you want to DiY a system. Islanding is just a requirement of any system that connects to the grid. What enables you to use your GT inverters when the grid goes down is a hybrid grid forming inverter that can AC couple to the GT, grid dependent, inverter{s}. The Tesla Powerwall is both a battery and inverter in one package. It is just one of many options available in the marketplace. The key search terms if you want to find out more are, "AC couple" and "Powerwall alternatives".
                          NOTE:
                          I just met a guy at dinner tonight that runs a Solaria dealership and he says the Enphase and SolarEdge batteries are competitive with the Tesla Powerwall. His company is in Santa Rosa, California. I also saw a page on the SunRun site that suggests they have an AC coupled battery. I am not advocating for either of those companies, but just documenting my earlier statement that there are lots of options to accomplish your goal of using the energy from your GT solar system when the grid is down/
                          Last edited by Ampster; 06-11-2022, 02:05 PM.
                          9 kW solar, 42kWh LFP storage. EV owner since 2012

                          Comment

                          • Charlie W
                            Member
                            • Oct 2016
                            • 60

                            #14
                            Originally posted by SunEagle

                            I would prefer that all solar sellers provide that info at the time they are suggesting a system. Unfortunately some people either won't understand or will look for a way to "trick" the inverter to think there is a grid.
                            I just posted a version of this question, and it's awaiting mod approval. I assure you that I am listening, and am utterly uninterested in "tricks." I realize that it has to be tiresome to field the same question, but look on the bright side. People come here (or at least some people) because the collective wisdom and integrity here is solid. I suggest treating the same irritating question as a compliment, because that's really what it is.

                            Comment

                            • SunEagle
                              Super Moderator
                              • Oct 2012
                              • 15125

                              #15
                              Originally posted by Charlie W

                              I just posted a version of this question, and it's awaiting mod approval. I assure you that I am listening, and am utterly uninterested in "tricks." I realize that it has to be tiresome to field the same question, but look on the bright side. People come here (or at least some people) because the collective wisdom and integrity here is solid. I suggest treating the same irritating question as a compliment, because that's really what it is.
                              I just approved that post.

                              Comment

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