I`m new on this forum, but I have my goodwe gw3648d-es since 2016. So, If I can help in anything, I´m happy to do it.
Best regards
Mauricio Quijada C.
Chile
Hello, I´m new on this forum, but are you try testing one battery bank at time?. Disconnect one of the battery bank conected in parallel, let it work for a wile and check. Then do the same with the other battery.
Good Luck!