I have a FoxESS inverter with a home battery and solar panels, installed about one month ago. Everything worked as expected until around the 14th of June, when the behavior changed.
Inverter: H1
Version_Master: 1.35
Version_Slave: 1.03
Version_ARM: 1.43
Yesterday evening around 8pm the battery dropped very fast, from about 85% to 20% in less than an hour, with nothing special running in the house. Then in the middle of the night it started to charge from the grid on its own, which it never did before.
When I look at the grid power meter, I now see flat rectangular plateaus at a fixed power, around +4500W (charging from the grid) and -4500W (discharging to the grid), lasting several minutes. This is very different from normal solar production or normal consumption, which are always noisy and irregular. A flat plateau at a fixed power looks like a forced charge or forced discharge order from the inverter.
On the attached screenshot (17 June, 00:00 to 16:00) you can clearly see these flat plateaus at about -4550W during the night and the morning, including periods when there is no solar production at all.
For comparison, a few days earlier (7-8 June) the grid meter was flat at zero during the night, with only noisy solar production during the day. No grid charging at night, no fixed plateaus.
My settings are the usual ones: minimum SoC 10%, maximum SoC 100%. I am in Self-Use mode, like since the beginning, and I checked: there is no schedule active. I did not change anything myself.
My installer told me that other clients seem to have the same issue, so it could be a firmware update that changed or activated something. One colleague also suggested it could look like a battery calibration run.
Is this a known behavior after a recent firmware update? Could something have been activated by itself even in Self-Use mode with no schedule? And if it is a calibration run, how often does it happen, because doing this when there is no solar production is a problem.
Thanks for any help.