There is no point in having the ability to store energy in the battery faster than your solar panels can generate it, or to discharge energy from the battery fa

There is no point in having the ability to store energy in the battery faster than your solar panels can generate it, or to discharge energy from the battery faster than your house is using it. So it seems that you would be interested in the power rating of the motor, such that for a small system a 10 HP motor would be fine. The torque and speed of the process are less relevant, as you'll just gear the motor to match the load (and possibly to keep the motor at peak efficiency).