PV voltage fluctuation when surplus charging battery
Hi, I have a 8kW Synsynk inverter connected to 3 x Sunsynk 5.32kW batteries and input from 4 x Euraner 450w panels. I do have a seprate Sunnyboy inverter and panels, but these I think don't play a part in the problem. When I set the timer to charge off grid (so I capture the surplus from both the Sunnyboy and Sunsysnk inverters) all is well. The voltage from the Euraner panels is rock steady and the batteries charge well. But when not on a timer setting and set to priority load I get a regular issue where the Euraner voltage becomes unsteady when the surplus is charging the batteries. The video shows the settings and behaviour, the power drops to near zero and then recovers. The dial voltmeter I attached shows the voltage 'ticking' over a 30 volt range. The battery is about 70% charged at this point. The voltage graph in the PPT shows the fluctuations. The battery still charges, but I can't think it is as effective as a steady voltage and do wonder if the fluctuations do anything any good or just an irritation. Nothing wrong with the panels, when I check those with a voltmeter, disconnected from the inverter, again rock steady. The fluctuations don't coincide with other grid activity such as EV charging, showers, etc, they seem to be random, but at higher power generation. Any thoughts, anyone else seen this?
I reckon jacekowski is on the money and as demonstrated when using the the 300V string it works as expected. Trying to operate the inverter with a string voltage of 150 V is just to low.