Today I discovered that when DESS schedules exporting excess solar energy to the grid instead of charging the batteries, it does so unevenly across the three phases. As a result, I end up buying electricity on one phase while exporting it on the other two.
In the screenshot below, the system is exporting a total of 1996 W to the grid, but the phase distribution is:
- L1: -468 W (export)
- L2: -2516 W (export)
- L3: +988 W (import)
This means that while the system is exporting nearly 2 kW overall, L3 is simultaneously importing almost 1 kW from the grid.
The issue is that my utility treats each phase separately. Energy imported on one phase is not offset by energy exported on another phase. In addition, the purchase price is roughly €0.10/kWh higher than the compensation received for exported energy. Therefore, even though the net power flow is approximately 2 kW exported, I am actually losing money.
Is there a setting that would prevent this behavior?
The MPPTs connected to the L3 inverter are producing approximately 2.8 kW, while the load on L3 is about 3.7 kW. The missing power is therefore being imported from the grid, whereas I would expect it to be supplied from the DC bus (battery/PV system).
In my opinion, the power flow should be balanced so that L1 and L3 are close to 0 W, with the excess power exported mainly on L2, resulting in approximately -2000 W on that phase.
Is this the expected behavior of DESS, or have I misconfigured something?
I know that there is an ESS setting for phase regulation “Total of all phases” or “Individual phase”, and I want the latter one, but this setting is not available for Multi RS Solar.
