Size an MPPT or PWM charge controller for a solar array and battery bank.
MPPT controllers convert excess array voltage into charging current and typically deliver 20 to 30 per cent more energy than PWM when array voltage substantially exceeds battery voltage. PWM is only sensible when array and battery voltages are closely matched; otherwise the wasted voltage difference is pure loss.
Solar Charge Controller
Controller amps = array watts × efficiency ÷ battery voltage × 1.25
Controller amps = array watts × efficiency ÷ battery voltage × 1.25 MPPT controllers convert excess array voltage into charging current and typically deliver 20 to 30 per cent more energy than PWM when array voltage substantially exceeds battery voltage.
PWM is only sensible when array and battery voltages are closely matched; otherwise the wasted voltage difference is pure loss.
This calculator takes 4 inputs: Array power, Battery bank voltage, Controller type, Array voltage at maximum power. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.