Hi all, Over the last three days I have had one of this infuriating and frustrating experiences with Sol-Ark where you talk to 3 people and get 10 different answers. At least I think I finally got the right one today. Here is the scenario and problem I was experiencing:
At a (very) remote location that is a boat ride away, I have three 15K inverters paralleled in a 120/240V system, off-grid, generator connected to the grid input (but not being used). The PV array connected to the DC inputs totals 40kW split across the three inverters. There is a 9.7kW Enphase system (8.4kW AC inverter rating) connected on the load side of the inverter outputs. Massive battery - 110kWh. Everything has been working well for a couple of weeks since we got it set up. Then, over the last three days, we began experiencing unexpected shutdowns where the inverter would repeatedly stop inverting and PV would stop charging. There was usually no indication of errors on the screen. Everything was just stopped, but the inverters remained on. Sometimes they would restart once, only to shut down again relatively quickly. We had to manually restart the inverters with the ON/OFF buttons. Then we started getting various errors, with F50 being the strange one that is not documented. I reached Sol-Ark, and they said the F50 points to an AC input issue, but the generator was not on, so that didn't make sense. I was on my own to double-check all of the wiring. But there was also an F41 Parallel System Stop error, which pointed me to that suggested cause. I realized that one of the inverters had a -1725 COMM firmware, whereas the others had -1726. I don't know how that happened because I'm certain that I had them all on the same firmware at one time. Anyway, I spent all day yesterday trying to reach Sol-Ark and getting the firmware to match. I thought we had the issue resolved by the time I left, as I was able to run the system for an hour without a shutdown. Then I got a call at noon today from the owner. Same problem. System shut down. I was able to reach Sol-Ark immediately this time and the agent gave me a more plausible answer. He said the F50 error points to something wrong with the AC coupling. We started to put our heads together and I realized that this issue first popped up around mid-day on Thursday, and then repeated itself mid-day on Friday. Here we are again today, and I get the call at noon. It seems like the issue happens as soon as the batteries reach 100% capacity. It's like the Sol-Ark is not commanding the IQ8A microinverters to shut down. I had the owner shut off the AC coupling input breaker and I remotely unchecked the box for AC coupling on the load side. That seems to have resolved the issue. Ok, fine, but how do we resolve this (I asked Sol-Ark)? The "solution" I was offered is to move the AC coupled input to the GEN terminals. The problem is that I need to reserve the GEN terminals for an upcoming Smart Load subpanel. That's why I installed the AC coupling on the load side, which is a documented and accepted practice. I do have AC coupling working without issue on a grid-tied system at another location with dual Sol-Arks, but that is connected to the GEN terminals. This is the first time I have AC coupled on the load side. Has anyone successfully AC coupled on the load side, particularly with microinverters? I'm probably going to have to climb the customer service ladder at Sol-Ark to get a resolution for this, but I wanted to get some feedback in case someone has already been down this road. Thanks in advance, Jason Szumlanski Florida Solar Design Group
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