Why in selfuse mode the excess pv production goes to the grid instead of charging the T58 battery which is in low SOC or the charging current appears to be limited?

The charging current will be affected by several factors such as SOC and cell temperature, when the cell temperature is extremely low (especially in winter) or high and the SOC is also low the charging current will be limited. And if the cell temperature goes to ≤ 0℃ the max charging current will be limited as 0, so in that case the battery can't be charged even if there's excess pv production.