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Looking for ideas on how to incorporate a generator in a large solar system.

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  • Looking for ideas on how to incorporate a generator in a large solar system.

    I'm in an area where poco is unreliable and raising rates faster then their power lines are starting fires. My monthly bill is about 500 not including all the fuel I have to burn in my generator. The rate is going up by 50% over the next 3 years.

    Im installing a 15kw grid tie system with 2 solar edge 7600 inverters. My power needs are roughly 50kwh a day in the summer and 34kwh a day in the winter.



    Im going to build a 120kw battery bank out of 3 Nissan leaf 40kw battery packs to take my house off grid. Im building 5 48v stacks wired in series to supply the inverters with 240vdc im also installing a 25kw diesel generator.

    My plan is to reconfigure the solar system when the battery bank is done so that the solar system is only charging the batteries through charge controllers. The batteries supply the inverters with 240vdc and the generator kicks in when the solar can't keep up.

    My question is what is the best way to combine the generator with the solar system. My thoughts were to build a rectifier bridge for the generator output and tie it to the pv input threw a hv dc link so that the charger controllers always have constant supply. The generator starts/stop signal would come from the battery voltage monitor.

    I'm open to ideas of a better way.

  • #2
    Welcome. First issue is the battery voltage. Going above 50VDC, puts you into the next tier of rules and regulations, with locked doors and restricted access to the "high voltage gear".

    second, what kind of inverters are you using with 240VDC ? Data center UPS systems ?
    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


    • #3
      As far as the high voltage regulations are concerned I work on both heavy duty diesel electric hybrid equipment and hydrogen fuel cell equipment. I have a very deep knowledge of both the safety aspect and regulations of working with high voltage and ups systems and the tools to work on them.

      The inverters Im going to use are solar edge se7600a-us they are a grid tie inverter with a max input dc voltage of 500vdc and a nom of 240vdc to 350vdc. Each one has a 240vac output @32amp and can be phase synced.
      Last edited by Farvaszx6r; 10-25-2019, 03:14 AM.

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      • #4
        Originally posted by Farvaszx6r View Post
        I'm open to ideas of a better way.
        If this is for something like a residential application, I'd start by getting on a serious energy use diet. You're a poster child for an energy audit.

        Comment


        • #5
          Originally posted by Farvaszx6r View Post
          The inverters Im going to use are solar edge se7600a-us they are a grid tie inverter with a max input dc voltage of 500vdc and a nom of 240vdc to 350vdc. Each one has a 240vac output @32amp and can be phase synced.
          So it sounds like you are talking about the first generation StorEdge inverter which has a DC input of 400V (both battery and solar).
          It also has a digital connection to the battery for control.
          You might try looking at the LG Resu10H spec sheet as that is the battery that work with the inverter.

          SolarEdge also doesn't work with charge controllers
          OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

          Comment


          • #6
            Originally posted by J.P.M. View Post

            If this is for something like a residential application, I'd start by getting on a serious energy use diet. You're a poster child for an energy audit.
            I have already started changing out major appliances for more efficient ones and I'm in the process of making the house more energy efficient. I run a side business from my home that requires me to use tools like a welder, air compressor and other power tools.

            If need be I can cut my energy consumption in half and run my shop off of generator power only. I'm just planning for the worst case.

            Comment


            • #7
              Originally posted by ButchDeal View Post

              So it sounds like you are talking about the first generation StorEdge inverter which has a DC input of 400V (both battery and solar).
              It also has a digital connection to the battery for control.
              You might try looking at the LG Resu10H spec sheet as that is the battery that work with the inverter.

              SolarEdge also doesn't work with charge controllers
              The inverters are actually the latest version. I under standard they will work directly with the lg battery but the cost on those batteries are still too high I would need 12 of them to run completely off grid.

              I can build my 120kw battery bank for a little over the cost of one of the lg packs.

              The core of the system is being installed as a grid tie system so that if I ever sell the house I can simply remove the battery setup and reconnect the pv input directly to the inverters. The system will be permitted and the house will much easier to sell.

              To use the battery bank I'm just taking the pv input from the inverters and connecting it to the charger controllers to change the batteries then I take the battery bank output and connect that to the pv input on the inverters. Kinda like dc coupling but the goal is to make sure the inverters always have constant supply of power. I'm just not sure how to incorporate the generator. I want to be able to charge the battery bank with the generator while running the house.

              Comment


              • #8
                Originally posted by Farvaszx6r View Post
                The inverters are actually the latest version.
                You said you had the SE7600A-US which is two generations behind on the inverters from SolarEdge. It is the current StorEdge but about to be replaced by the StorEdge interface that works with all the HDWave versions.

                Originally posted by Farvaszx6r View Post
                I under standard they will work directly with the lg battery but the cost on those batteries are still too high I would need 12 of them to run completely off grid.
                You need to go on a serious off grid energy diet!

                Originally posted by Farvaszx6r View Post
                I can build my 120kw battery bank for a little over the cost of one of the lg packs.
                not much good if it doesn't work though...

                Originally posted by Farvaszx6r View Post
                The core of the system is being installed as a grid tie system so that if I ever sell the house I can simply remove the battery setup and reconnect the pv input directly to the inverters. The system will be permitted and the house will much easier to sell.
                Why don't you just leave it grid tied and skip the batteries all together, or if you want backup get one LG RESU10H.
                It would save you money and most importantly work.
                Do you have Net metering?

                How are you going to permit something like this???

                Originally posted by Farvaszx6r View Post
                To use the battery bank I'm just taking the pv input from the inverters and connecting it to the charger controllers to change the batteries .
                Ok so you can charge the battery with Charge Controllers...(assuming they work with that voltage battery).

                Originally posted by Farvaszx6r View Post
                then I take the battery bank output and connect that to the pv input on the inverters.
                doubt that will work, but the StorEdge wants ~400V DC on the bus and to communicate with optimizers and/or the battery. How are you going to get it to communicate with your battery?

                Originally posted by Farvaszx6r View Post
                Kinda like dc coupling but the goal is to make sure the inverters always have constant supply of power. I'm just not sure how to incorporate the generator. I want to be able to charge the battery bank with the generator while running the house.
                well you will not be able to use the StorEdge inverter battery charging circuit as it will not know there is a battery since it can't communicate with it.
                OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

                Comment


                • #9
                  My apologies you are correct it is the se7600h-us I had to look at my contract.


                  To answer most of your questions I'm having a local solar installer install a 15000w grid tie system it will be permitted and have net metering. 48 hanwha q cell 325w panels and 2 solar edge se7600h-us inverters with solar edge optimizers if it continues to work out great then I won't change anything.

                  I'm in California and have pg&e. They just got authorization to rase rates 50% over the next 3 years to cover the billions they lost over wildfires. My current rate is .38 cents. There is a lot of uncertainty as to whether or not they will be broken up or if they will get the green light to impose a solar production fee because they are losing money from all the people going solar. I want the ability to not have to rely on the poco

                  I am going to leave the system as grid tie with a backup generator for the time being but as of late I have had to run my house off a generator for a total of 14 days this month alone due to wildfire concerns and my power is scheduled to be cut for 4 more days starting tomorrow. Generators are expensive to run and I have a fear of not having enough battery capacity in the fall/winter time with the current options available.

                  I haven't purchased anything yet other than the contract for the grid tie system. I'm only in the design phase for an off grid system.

                  I was under the impression that I could use 240vdc and be able to produce 240vac with the se7600. If I need 400vdc as input voltage then I would just need to reconfigure the battery bank and get a 408v generator. The cost difference between a 240 and 408v diesel gen set is minimal.

                  My original battery configuration was 5 stacks @ 48v wired in series to produce 240vdc output. Each stack has 2 modules so I have the ability to hot swap a bad module without going dark. That will have to be reconfigured now.

                  The stacks are broken up into 48v for 3 reason. First is 48v change controllers are fairly inexpensive and readily available. Second It also lessens the complexity of bmc's and makes it easier to keep track of cell health. Third is hot swap capabilities.

                  I'm not 100% sure yet how to connect the optimizer on the panels to the inverters I need to do a bit more research on how they actually talk to each other. I'm assuming that the inverters are monitoring the output of the panels on a separate connection. If that is the case then were the input voltage to the inverter comes from is irrelevant as the inverters can shut down individual panels as needed and the bmc's will nominalize stack voltage.

                  From my understanding the solar edge inverters can be used off grid by looping the 240vac from the output to the grid input to keep the inverter on and it will stay on until the inverter input voltage drops to the point it can't maintain nominal 240vac. A generator is needed to restart the system after a shutdown occurs.

                  As for an energy diet the system Im trying to build is oversized. I have to use high consuming equipment to make money. Welders, mill machine ect. I would much rather have more then enough and scale back then to have to reconfigure to expand.



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                  • #10
                    Originally posted by Farvaszx6r View Post
                    My apologies you are correct it is the se7600h-us I had to look at my contract.
                    that is NOT a bimodal inverter and will not work with a battery unless you get the as yet not released StorEdge interface to add to it, as well as auto transformer and approved battery with digital connection (I.E LG Resu10H or future SolarEdge battery).


                    Originally posted by Farvaszx6r View Post
                    To answer most of your questions I'm having a local solar installer install a 15000w grid tie system it will be permitted and have net metering. 48 hanwha q cell 325w panels and 2 solar edge se7600h-us inverters with solar edge optimizers if it continues to work out great then I won't change anything.

                    I'm in California and have pg&e. They just got authorization to rase rates 50% over the next 3 years to cover the billions they lost over wildfires. My current rate is .38 cents. There is a lot of uncertainty as to whether or not they will be broken up or if they will get the green light to impose a solar production fee because they are losing money from all the people going solar. I want the ability to not have to rely on the poco

                    I am going to leave the system as grid tie with a backup generator for the time being but as of late I have had to run my house off a generator for a total of 14 days this month alone due to wildfire concerns and my power is scheduled to be cut for 4 more days starting tomorrow. Generators are expensive to run and I have a fear of not having enough battery capacity in the fall/winter time with the current options available.
                    I would suggest that you stick with grid tie. off grid is never going to pay for itself.
                    Backup for some loads is different though still not likely to pay for itself is much less of an expense.

                    Originally posted by Farvaszx6r View Post
                    I haven't purchased anything yet other than the contract for the grid tie system. I'm only in the design phase for an off grid system.
                    Well what you have been talking about is not going to work and is not designing but day dreaming...

                    Originally posted by Farvaszx6r View Post
                    I was under the impression that I could use 240vdc and be able to produce 240vac with the se7600. If I need 400vdc as input voltage then I would just need to reconfigure the battery bank and get a 408v generator. The cost difference between a 240 and 408v diesel gen set is minimal.
                    The SE7600H requies 400V DC input. Most 408V generators are three phase AC.
                    More so though the SE7600H does not have a battery interace, it will eventually connect to the StorEdge interface which will also need a 400V battery and it will have to be a smart battery that communicates to the StorEdge interface ditigally.

                    Originally posted by Farvaszx6r View Post
                    My original battery configuration was 5 stacks @ 48v wired in series to produce 240vdc output. Each stack has 2 modules so I have the ability to hot swap a bad module without going dark. That will have to be reconfigured now.

                    The stacks are broken up into 48v for 3 reason. First is 48v change controllers are fairly inexpensive and readily available. Second It also lessens the complexity of bmc's and makes it easier to keep track of cell health. Third is hot swap capabilities.
                    There are MANY 48V inverters that can work with that battery like from OutBack, Schneider, etc etc.

                    Originally posted by Farvaszx6r View Post
                    I'm not 100% sure yet how to connect the optimizer on the panels to the inverters I need to do a bit more research on how they actually talk to each other. I'm assuming that the inverters are monitoring the output of the panels on a separate connection. If that is the case then were the input voltage to the inverter comes from is irrelevant as the inverters can shut down individual panels as needed and the bmc's will nominalize stack voltage.
                    No, the optimizers do the voltage regulation and the communicate on the DC lines. The battery has a separate communication on the modbus, and does not communicate like the optimizers.

                    Originally posted by Farvaszx6r View Post
                    From my understanding the solar edge inverters can be used off grid by looping the 240vac from the output to the grid input to keep the inverter on and it will stay on until the inverter input voltage drops to the point it can't maintain nominal 240vac. A generator is needed to restart the system after a shutdown occurs.
                    WHERE are you getting this understanding? it is far from accurate and will not work.

                    Originally posted by Farvaszx6r View Post
                    As for an energy diet the system Im trying to build is oversized. I have to use high consuming equipment to make money. Welders, mill machine ect. I would much rather have more then enough and scale back then to have to reconfigure to expand.
                    Then stay ON GRID.
                    OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

                    Comment


                    • #11
                      Originally posted by Farvaszx6r View Post

                      I have already started changing out major appliances for more efficient ones and I'm in the process of making the house more energy efficient. I run a side business from my home that requires me to use tools like a welder, air compressor and other power tools.

                      If need be I can cut my energy consumption in half and run my shop off of generator power only. I'm just planning for the worst case.
                      Thank you. Understood. What role does overall cost effectiveness play in the plans ?

                      Comment


                      • #12
                        Originally posted by ButchDeal View Post

                        That is NOT a bimodal inverter and will not work with a battery unless you get the as yet not released StorEdge interface to add to it, as well as auto transformer and approved battery with digital connection (I.E LG Resu10H or future SolarEdge battery).

                        Yes it is not a bimodal inverter but it has been used in ac coupled hybrid systems with out lg batteries.


                        I would suggest that you stick with grid tie. off grid is never going to pay for itself.
                        Backup for some loads is different though still not likely to pay for itself is much less of an expense.

                        That is the plan at this point. I am fully aware that going off grid is not a financial decisions for me it is both curiosity to see if it can be done and a deep despise for pg&e. I also want to do an off grid 3 phase system for my shop because 3 phase equipment is substantially cheaper then single phase.


                        Well what you have been talking about is not going to work and is not designing but day dreaming...

                        That is why I'm asking questions before I go spend money and perhaps it is a day dream but that's what people thought about the Wright brothers.

                        The SE7600H requies 400V DC input. Most 408V generators are three phase AC.
                        More so though the SE7600H does not have a battery interace, it will eventually connect to the StorEdge interface which will also need a 400V battery and it will have to be a smart battery that communicates to the StorEdge interface ditigally.

                        I thank you missed the part about using a rectifier bridge. I use high voltage rec bridges at work that are rated at 1000v and 400amp and the parts to make one are relatively inexpensive and easily accessible.

                        There are MANY 48V inverters that can work with that battery like from OutBack, Schneider, etc etc.

                        This is true but now we are substantially increasing amperage loads and wire size both are costly in large solar systems. Also I want something that is easily reversed and can be reconnected to the grid because not many people will want to deal with a complex system.


                        No, the optimizers do the voltage regulation and the communicate on the DC lines. The battery has a separate communication on the modbus, and does not communicate like the optimizers.

                        Then would it make more sense to break up the array into multiple arrays with their own charge controller?

                        WHERE are you getting this understanding? it is far from accurate and will not work.

                        My apologies that doesn't make much sense the way I wrote it. What I meant was using a small inverter that pulls power from the battery bank to keep the solaredge on and to activate rapid shut down should something catastrophic happen. Something similar to how they are used in hybrid ac coupling battery backup systems.


                        Then stay ON GRID.
                        That would be nice if the grid was reliable. I live in a rural area not in the city. If power outages were a once and a while thing I would do like the rest of the mainstream solar systems.

                        In your opinion what would be a more plausible off grid solution given the energy requirements I listed in the original post?
                        Last edited by Farvaszx6r; 10-25-2019, 03:51 PM.

                        Comment


                        • #13
                          Originally posted by J.P.M. View Post

                          Thank you. Understood. What role does overall cost effectiveness play in the plans ?
                          I want to spend less then $500 to $600 a month on energy and I want reliable power.

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                          • #14
                            Butchdeal some how my replies got mixed in with your quotes.

                            Comment


                            • #15
                              Originally posted by Farvaszx6r View Post
                              ...

                              The inverters Im going to use are solar edge se7600a-us they are a grid tie inverter with a max input dc voltage of 500vdc and a nom of 240vdc to 350vdc. Each one has a 240vac output @32amp and can be phase synced.
                              You will have to use a UPS battery based inverter, or find a way to disable the MPPT controller of a solar inverter. The MPPT input is expecting a CURRENT SOURCE, batteries are a Voltage Source and will not work well with a MPPT controller. Most likely, the battery will win and fry the MPPT controller in a couple minutes. MPPT controllers operate by adjusting the PV array voltage till they get the best current. That can't be done with a battery, the controller will start the voltage sweep and something is going to fail.
                              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

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