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  • Small scale solar, almost a hobby...

    Hi everyone! I have 2 100 watt panels, a 20amp MPPT charge controller/negative ground (Epever), and a 100ah vmaxtanks battery. I use it mainly for backup power to less than 5 amps of 12v internet/electronic stuff. I do have an inverter but rarely use it, it's wired into one of my house circuits and when on (again, rarely) and it kicks in when power goes out. That's about it.

  • #2
    Hello MarkNewYork and welcome to Solar Panel Talk

    Glad to have you here. There are other members that have small systems similar to yours except the part that it is "wired into one of my house circuits". That part scares me because it can cause a fire if not performed per code.

    A stand alone solar/pv "off grid" system is ok but once you make a connection to your home circuit panel it becomes a "grid tied" system and must meet local codes along with the POCO's permission.

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    • #3
      SunEagle thanks so much for your comments and concern. The unit I'm using is not grid tied in the sense that it feeds power back into the mains. This unit senses when power goes out and takes over providing power to a particular circuit - it switches the load off the mains (after the breaker) and onto its inverter. The inverter is pure sine wave with a standard ground and neutral I was told can be wired into a house circuit in this way. Link to the unit below - please let me know if you feel this is a hazard. And here is the question I asked about it with the answer. Would really appreciate any thoughts you have on this. Thanks for this forum!

      Question I asked: "Will this integrate well into standard US home AC wiring? Would like to put the AC hookup between a breaker in the fusebox and its associated loads/outlets. Will be powered by a negative ground MPPT solar charger/100 AH battery."

      Answer I got: "Yes this inverter can be wired to a home breaker box. Please keep in mind that you cannot bypass more than 30A from the grid through the inverter."

      here's a link to the unit I have:
      https://www.aimscorp.net/2000-pure-s...standards.html

      Comment


      • #4
        If the inverter is connected to a panel that is also connected to the grid it must have a UL 1741 listing to be legal. The equipment must shut down if the grid is down and/or have a transfer switch that are both recognized by UL to guarantee disconnection between inverter and the grid. To do that UL must test the equipment to give it the 1741 listing,

        From what I can find, the manufacturer of that inverter mentions UL 458 but not 1741 which means it is not recognized by UL for grid connections.

        The manufacturer may say their product is safe and legal but if a fire should happen your home owners insurance may not feel you are using legal equipment and then not pay for any damages.

        Keeping the inverter totally separate from your house panel is the only way to keep it safe.

        There is other equipment out there that can signal an inverter to let it know the grid is down but unless the transfer switch or disconnecting equipment is UL 1741 listed you can run into a legal hassle.

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        • #5
          Thanks, I see your point but I'm under the impression that although this unit is connectedto my panel, and the panel is connected to the grid, the unit is not "grid tied." The inverter is only connected to the grid at it's AC input, not any AC output. The only thing the inverter will ever supply power to is the load connected to its AC output. Grid power is fed to the load when the grid is on. When the grid goes off the unit turns off the grid connection and starts supplying power to the load itself. I see it as operating exactly the same way as a standard Uninterrupted Power Supply (UPS). Those are also connected to both the load and the grid (through a plug.) They both will never feed power out of the house into the grid under any circumstances - so why would it need to shut down via a UL1741 transfer switch when the power goes out? In my eyes it really is just a UPS with a solar charger and really big battery. I really appreciate your help and don't in any way mean to question what you are saying, just hoping to fully understand what this thing really does.

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          • #6
            Originally posted by MarkNewYork View Post
            Thanks, I see your point but I'm under the impression that although this unit is connectedto my panel, and the panel is connected to the grid, the unit is not "grid tied." The inverter is only connected to the grid at it's AC input, not any AC output. The only thing the inverter will ever supply power to is the load connected to its AC output. Grid power is fed to the load when the grid is on. When the grid goes off the unit turns off the grid connection and starts supplying power to the load itself. I see it as operating exactly the same way as a standard Uninterrupted Power Supply (UPS). Those are also connected to both the load and the grid (through a plug.) They both will never feed power out of the house into the grid under any circumstances - so why would it need to shut down via a UL1741 transfer switch when the power goes out? In my eyes it really is just a UPS with a solar charger and really big battery. I really appreciate your help and don't in any way mean to question what you are saying, just hoping to fully understand what this thing really does.
            You may be correct if the output of your inverter is only connected by a plug to a separate load and not to the loads in your panel. When the power goes out it sounds like it is a hardwired UPS..
            9 kW solar, 42kWh LFP storage. EV owner since 2012

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            • #7
              Ampster, thanks for your insight - it is in fact hard wired and not using plugs/outlets. I'm curious how that makes a difference? They both are electrical connections and operate in the same way. So how would safety be affected by one method or the other?

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              • #8
                Originally posted by MarkNewYork View Post
                Ampster, thanks for your insight - it is in fact hard wired and not using plugs/outlets. I'm curious how that makes a difference? They both are electrical connections and operate in the same way. So how would safety be affected by one method or the other?
                A hard wired inverter to a main panel can provide power to any load on the panel which can either overload it or feed back into the grid.

                An inverter with an outlet that you can plug in a load will only allow that load to be powered and usually has over-current protection for that load. It will also not feed back into the grid.

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