Charge Controller Sizing Calculator
Size MPPT or PWM charge controllers for safe operation.
Charge Controller Sizing Calculator estimates the current rating needed for a solar charge controller from PV array power, battery-bank voltage, and safety margin. A charge controller regulates energy flowing from panels into batteries; MPPT controllers convert excess panel voltage into charging current more efficiently, while PWM controllers operate closer to battery voltage and are usually simpler. Controller ampacity is the current the device can safely carry without overheating or current-limiting. The basic sizing relation divides array watts by battery voltage, then adds headroom for continuous operation, heat, and measurement uncertainty. This calculator is useful for comparing MPPT and PWM controller ratings, but cold-weather voltage, controller input limits, array wiring, battery chemistry, fusing, and electrical code requirements still need separate verification.