Problem multi battery SolarEdge system during backup

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  • kramedt
    Junior Member
    • Jun 2018
    • 9

    Problem multi battery SolarEdge system during backup

    Does anyone have a Solaredge system with two solaredge batteries each connected to separate energy hub inverters? That is what I have and the problem I have is that during a grid outage instead of proportionally discharging from both batteries (which is what it does during a self consumption profile while grid is up) it instead only draws from the main inverter/battery and only draws from the secondary if I exceed the max power output (5kw) of the battery. Since during a grid outage I aggressively load shed that essentially means only one of my batteries is ever used. To make matters worse the one time we had an extended outage when the main battery fully depleted the main inverter shut down and the whole system went offline and wouldn’t come back up until the grid came back. Even though I had a completely full second battery. Both myself and my installer contacted solaredge and they claim this is as designed. I find that incredibly hard to believe as that seems to be a very poor design. Let’s just say even if it did gracefully switch to the 2nd battery after the first depleted, then I would now have a max power output of 5kw instruction of 10 which was one of the points of getting two batteries in the first place. I’m wondering if anyone else has a similar setup and if so does your system behave the same way?
  • chronos432
    Junior Member
    • Feb 2023
    • 23

    #2
    Hi kramedt, thanks for alerting us to this. I assume that since it did run off 3 batteries evenly (I tested this on 10/13 this month) in self-consumption mode it would do so in backup mode with the grid out. I have 3 x 7.6kW inverters, each with its own LG RESU PRIME 16H. I assumed that I had 48 kWh of backup, but if this is true I only have 16 kWh... not what I paid for.

    I just flipped the main AC breaker to see what happened, and it is pulling down only the 1st battery like you said. I'll have to see what happens when the 1st battery hits zero!

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    • kramedt
      Junior Member
      • Jun 2018
      • 9

      #3
      To be fair solar edge did tell me that when my first battery was depleted it was supposed to switch to the 2nd. Why it didn’t I don’t know so that still needs to be resolved. But even if it is, I still have a problem with it using one battery at a time due to the fact that I lose continuous power output of the 1st battery after it is depleted. I will be requesting a firmware change for this though it doesn’t sound like they have a formal suggestion box so I have to file a support complaint to get it in.

      Comment

      • chronos432
        Junior Member
        • Feb 2023
        • 23

        #4
        Actually I just depleted my first 16 KWH battery and it auto switched over. More to come. So yours isn’t behaving as it should.

        Comment

        • chronos432
          Junior Member
          • Feb 2023
          • 23

          #5
          Ok, had to put kids to bed before I could reply.

          So I went and turned off the main breaker near the street which is "upstream" of everything. I do have the SE Backup interface ver 2.

          I have 3 7600H inverters, each of which has a LG RESU PRIME 16H attached. When power went out, it actually was draining the first follower battery (not the leader). I flipped the breaker just before 4pm.

          I turned on a lot of appliances to draw down the battery fast. It hit 10% at 8pm and that's when the next inverter/battery kicked in. I'm not sure if the choice is random or if there is some algorithm behind it.

          Also, I can confirm that another inverter will kick in to provide extra power as my draw went to about 9.4 kW which is above the 7kW continuous limit for a RESU PRIME 16H. As you can see from the chart below, inverter 1 kicked in to provide power.

          My installer has been following this thread and my test today, and his thought is that you should look closely at the leader/follower configuration of your inverters. I assume you do have a BUI? and also the comms cabling is crucial.. needs to be wired correctly and also Cat 6 shielded. My installer took a lot of care and time to get the multi battery scenario up and working. Very grateful for his attention to detail!!

          Screenshot 2023-10-22 212501.png
          Attached Files

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          • kramedt
            Junior Member
            • Jun 2018
            • 9

            #6
            Thanks for that test. I’ve run several myself, in my case it’s always the leader whose battery is used first. Though I do need to run a test where I fully deplete the battery as I haven’t had a chance to do that. I speculate, with no evidence to support my assumption, that when the leaders batter depleted it shut down and when it shut down the followers couldn’t produce. I do have a BUI. Though I have solaredge batteries not the LG ones. Is there a configuration or wiring that forces the system to use the followers first? Because that would certainly be better than how mine is working.

            Comment

            • chronos432
              Junior Member
              • Feb 2023
              • 23

              #7
              Here's the final result of my overnight test. So it automatically switched over from battery to battery when the "active" battery hits 10%. Not sure which exact one is connected to the leader, have to do more digging to find out. An algorithm which saves the leader for last is probably desirable, or better yet a system that does not shut down the leader when the leader battery is depleted if there is another full battery available.

              I would have your installer carefully check the comms cabling and leader/follower settings unless you're 100% sure that's rock solid. LG vs Solaredge batteries might have something to do with it too.

              Screenshot 2023-10-23 104559.png

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