Hello! We have a situation of an unreliable grid with an essential load that requires backup.
We have installed a grid-connected backup system with solar array consisting of 1 x 10 kW Quattro, 1 x MPPT 250/100, 6 kWp solar array , Trojan 375 Ah @ 48VDC lead acid battery bank and CCGX. We have configured ESS and allowing feedback into the grid, set in mode "Optimized (with batterylife)" and "minimum SOC 100% (unless grid fails)". Battery monitor set to Quattro. Has no DC system. DVCC off. All loaded with latest FW.
The system is performing nicely most of the time, but about half the time they system restricts the solar yield to 0W and indicating on the display "ESS #1 #2" messages. Sometimes it actually cycles from restraining the solar for 100% , then allowing solar to generate, cranking up the solar, the ESS #1 #2 messages disappear and then the message appears again and solar is forced to zero W again.
The inverter works fine in case of grid failure, but it actually seems erratic behavior of the solar controller.
In the below graph, solar is suddenly restrained while there is plenty of sun. The battery bank remains at 100% SOC. The system does not regenerate any error messages, except the status message "ESS #1 #2" on the CCGX display.
I have a sense that there is a conflict between the inverter/charger battery charging protocol and the solar charging protocol, although the battery monitor has been set to "Quattro" (so the controllers are listening to CCGX, dictated by the Quattro, how I understand it). The reason I think there may be a conflict is the following: the battery voltage during daytime (solar power is available) is stable at 55V float voltage, while at night the battery voltage fluctuates between 50.5 V and 55 V.
Q: What can cause the issue that the solar controller is constrained in producing power to feedback into the grid? What is causing the battery voltage to fluctuate in the night (controllers off) and in daytime it is constant? And what is allowing the solar about half the time to work without any issue? We are happy to share the VEconfig file in case required.
Thank you in advance for your insight!