A car needs at least 6 A per phase to charge, about 1.3 kW on one phase. The charger starts a solar session as soon as that much surplus is available, after the consumption of the household has been subtracted. How strictly this is applied depends on the solar strategy:
Pure Solar has an offset of 0 A. Charging starts only when at least 6 A of surplus is available, without using grid power.
Smart Solar has an offset of 4 A. Charging can start earlier, with up to 4 A (about 0.9 kW) from the grid to reach 6 A.
Fast Solar has an offset of 5 A. Charging starts even earlier, with up to 5 A from the grid.
Cars that charge on one phase
If your car charges on one phase, only the 6 A threshold matters. The charger may be connected on three phases, but the car only draws from one. The meter measures the total surplus across all phases, so the charger looks at the overall balance.
Cars that charge on three phases
If both the car and the charger support three phase charging, the charger starts on one phase and switches to three phases when about 4 kW of surplus is available.
For a full explanation, read How does solar charging work with Peblar?