I have Fox ESS 48kw and 15kw Inverter. I have noticed in my power bills that power is still used from the grid . According to Fox Suport - the following needs to be reviewed During our testing, the load reading on Phase 1 becomes negative as soon as forced charging starts. In addition, the increase in the Grid CT reading on Phase 1 is significantly smaller than that of the other two phases. These readings suggest that the Grid CT on Phase 1 may not be installed or positioned correctly. Your installer will need to inspect the CT placement and wiring on-site.