Announcement

Collapse
No announcement yet.

Grid tie with back up generator - any one have this setup?

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Grid tie with back up generator - any one have this setup?

    Hi All,

    I'm in the process of getting quotes for a 14 kW grid tie and find myself leaning towards purchasing a Solarworld 315 panel /Solaredge system for about 2.85/watt and have found this forum to be a great resource

    Our area is subject to several power outages (3-30 hours) each year (averaged over the last 20 years). Consequently I've tied in a 10kW generator coupled via a transfer switch. It's a manual process for me to turn the gasoline generator on, plug it in to the house, flip the transfer switch, and then turn specific breakers on (in a sub-panel).

    My assumption (will review and confirm these concerns with my installer) is that when running the generator it would not negatively affect the solar system (in collection mode or not) - is this correct? Another concern I have is when the generator is running and the electric service comes back on - are there any issues that may arise or that I should be concerned about? I'm sure there are many gurus out there -but I'm not sure so I thought to ask to be sure.

    Again I will vet these concerns with the installer (not yet selected) who is a reputable and experience solar grid tie installer. Any feedback or comments are greatly appreciated.
    Kind Regards,
    Joe - SW280 Black Monos/SolarEdge

  • #2
    It is often done. You would have them install the solar inverter output on the grid side of the transfer switch, therefore when the grid is isolated from the generator, so is the solar. The solar inverter will disconnect itself automatically, so there is no worry about it feeding into the grid during an outage. You do not want the solar to ever backfeed into the generator, it will damage the genny.
    Solar Queen
    altE Store

    Comment


    • #3
      Originally posted by Joe in Maryland View Post
      Hi All,

      I'm in the process of getting quotes for a 14 kW grid tie and find myself leaning towards purchasing a Solarworld 315 panel /Solaredge system for about 2.85/watt and have found this forum to be a great resource

      Our area is subject to several power outages (3-30 hours) each year (averaged over the last 20 years). Consequently I've tied in a 10kW generator coupled via a transfer switch. It's a manual process for me to turn the gasoline generator on, plug it in to the house, flip the transfer switch, and then turn specific breakers on (in a sub-panel).

      My assumption (will review and confirm these concerns with my installer) is that when running the generator it would not negatively affect the solar system (in collection mode or not) - is this correct? Another concern I have is when the generator is running and the electric service comes back on - are there any issues that may arise or that I should be concerned about? I'm sure there are many gurus out there -but I'm not sure so I thought to ask to be sure.

      Again I will vet these concerns with the installer (not yet selected) who is a reputable and experience solar grid tie installer. Any feedback or comments are greatly appreciated.

      As Amy says, connect it to the utility side of the transfer switch. Generators can be damaged if they are backfed, so you want to eliminate that possibility completely. To tie this in, it will usually rely upon the supply-side connection and feeder tap rules in the NEC. Also, be aware that many utilities do not permit you to make any connections inside the meter enclosure, so you have to find another enclosure behind the meter to make this tap.

      In such a setup, the solar will work the same way that it does in a power failure on an ordinary grid-tied setup. The inverter(s) will shut off upon loss of grid power, and they will come back on after waiting 5 minutes for the grid to stabilize, when the grid is restored. They will remain off, while the grid is down.

      Unfortunately, this does mean that you are "leaving sun on the roof", whenever your transfer switch is in generator mode. It is possible to continuously monitor your loads, and "throttle" the inverter(s) to not exceed them in order to avoid backfeeding the generator. This will likely require special monitoring equipment, compatible with the specific inverters.

      There are even more advanced systems that allow all 5 power flows to interact. Utility, generator, batteries, solar, and the loads.

      Comment


      • #4
        Originally posted by Amy@altE View Post
        It is often done. You would have them install the solar inverter output on the grid side of the transfer switch, therefore when the grid is isolated from the generator, so is the solar. The solar inverter will disconnect itself automatically, so there is no worry about it feeding into the grid during an outage. You do not want the solar to ever backfeed into the generator, it will damage the genny.
        Hi Amy,

        Thanks very much for the quick reply, I was hoping this was a 'simple one' and the others have had this constraint too and will be sure that it is set up does not allow a backfeed into the generator.


        I did do a search on transfer switches and did not find an obvious answer for me to.
        Kind Regards,
        Joe - SW280 Black Monos/SolarEdge

        Comment


        • #5
          Originally posted by carultch View Post
          As Amy says, connect it to the utility side of the transfer switch. Generators can be damaged if they are backfed, so you want to eliminate that possibility completely. To tie this in, it will usually rely upon the supply-side connection and feeder tap rules in the NEC. Also, be aware that many utilities do not permit you to make any connections inside the meter enclosure, so you have to find another enclosure behind the meter to make this tap.

          In such a setup, the solar will work the same way that it does in a power failure on an ordinary grid-tied setup. The inverter(s) will shut off upon loss of grid power, and they will come back on after waiting 5 minutes for the grid to stabilize, when the grid is restored. They will remain off, while the grid is down.

          Unfortunately, this does mean that you are "leaving sun on the roof", whenever your transfer switch is in generator mode. It is possible to continuously monitor your loads, and "throttle" the inverter(s) to not exceed them in order to avoid backfeeding the generator. This will likely require special monitoring equipment, compatible with the specific inverters.

          There are even more advanced systems that allow all 5 power flows to interact. Utility, generator, batteries, solar, and the loads.
          Hi Carultch,

          Thanks for your detailed reply, that's good news about the power failure scenario - 'leaving the sun on the roof' seems to be a small price to pay while the generator is running - so I'm good with that without having specialty monitoring equipment during outages.
          Kind Regards,
          Joe - SW280 Black Monos/SolarEdge

          Comment


          • #6
            Hi
            I understand the in order for me not feed to the generator I need to connect the inverter to the utility side. I do have another question though. The only reason why I would turn on the generator is in case the power outage is for more than a few hours at night and only to avoid the batteries going below 50%. So essentially it is to charge the batteries.
            What do I need to do to make this happen.
            THanks

            Comment


            • #7
              Originally posted by noshali View Post
              Hi
              I understand the in order for me not feed to the generator I need to connect the inverter to the utility side. I do have another question though. The only reason why I would turn on the generator is in case the power outage is for more than a few hours at night and only to avoid the batteries going below 50%. So essentially it is to charge the batteries.
              What do I need to do to make this happen.
              THanks
              You need a high rate battery charger, plug it into the generator, and charge the batteries with it.

              Often, large off-grid inverters, have provisions to connect a generator to them and become 100A battery chargers.

              What sort of gear do you have currently ?
              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


              • #8
                Originally posted by Mike90250 View Post

                What sort of gear do you have currently ?
                I have a 3 phase 10KW inverter that has a 120 amp charger
                11KW solar panels
                600AH gel batteries

                In Pakistan you have to have individual split ACs. I have inverter ACs that do not have torque so can run very nicely on the inverter.

                Comment


                • #9
                  I have a 3 phase 10KW inverter that has a 120 amp charger
                  11KW solar panels
                  600AH gel batteries
                  Well, in the manual for the inverter, should be info on how to attach a 3phase generator to allow battery charging.

                  You will need a Solar Charge Controller for your Solar panels, to allow regulated charging of the batteries.

                  Lets hope there is a translation or typographic error about the batteries, GEL batteries are not suitable for solar recharging, but sealed AGM (Absorbed Glass Mat) are suitable.

                  Gel batteries have a chemical gel in the electrolyte which will only allow slow charging, AGM batteries have liquid electrolyte that is held in place by fiberglass fibers, but it cannot spill. AGM is a very robust battery, but has a shorter lifetime.
                  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


                  • #10
                    Here's my 200A solar feed connecting ahead of the main (service meter side) in my 400A Thomson generator transfer switch. The 400A service has parallel 4/0 copper. Enphase has an interesting paper addressing the required configuration. My house is large and all electric with a typical heating or cooling load of 20-25KW, so I'd need a huge system to run 9 tons of geothermal. That doesn't include the two 10KW electric backup strips. Not currently planning that unless I hit the lottery! Here's the Enphase link http://www.google.com/url?sa=t&rct=j...,d.eXY&cad=rja . Picture of my solar feed: 200A Feed.jpg
                    Jeff, BSEE, 22.3KW, 45-240W w/M190, 46-260W w/M250

                    Comment

                    Working...
                    X