PV throttling unexpectedly

[nickdb (Nick)]

This is a repeat of a previous topic:

ESS throttling MPPT without valid reason (AC + DC system, battery not full, reproducible

Hi, thanks for sharing your experience. That’s interesting, especially that a brand new fuse was already open – I wouldn’t expect that either. In my case, the issue turned out to be a bad MC4 crimp connection, which caused unstable behavior under higher current. But I agree with your point – having each string fused and properly separated definitely makes troubleshooting much easier. Thanks again for the input.

It also references this topic:

Venus OS v3.70 - MPPT 150/100 VE.Can with DC-side export enabled suddenly stops charging

This morning I worked with a colleague to see what is going on. There is a step in the logic of the Multi where it will not raise the charge voltage (for the solar chargers) while it is still charging from AC-in. In a system with a PV-inverter on the input side, like yours, it will be importing that energy and charging the battery. So the system is charging from AC-in. Once the battery gets full enough, so that it stops accepting charge current, the Multi will then raise the charge voltage. …

Where this can happen due to PV being on AC IN, resolved by moving it to AC OUT.