Yes, you got it right.

Thank you so much. I've learned a lot from the people in this forum.

So if my calculations are correct, Enphase configured the batteries to provide 8 amps during "normal" discharge cycle.

3,840Whrs / 240v = 16Ahrs.

Applying the 50% setting 8 amps per hr at 240 volt. Or 16 amps at 120 volts.

It's a 5kWhr battery with a 15% reserve leaving 4,250Whrs useable. (Assume new battery, no degradation.)

So if I had a 1,500 watt 120 volt resistive heater, (assuming 100% duty cycle) current draw would be 12.5a.

Runtime (assuming 100% draw from the batteries and no additional heat loss from the higher current) would be 4,250/1500 = 2.83 hours.

Are my calculations correct?