Solar Charge Controller Calculator

Calculate the appropriate size charge controller for your solar power system based on your solar array specifications and battery configuration.

MPPT is more efficient but costlier, PWM is simpler but requires matched voltages
Found on panel specifications (typically 37-45V for 12V panels)
Found on panel specifications (typically 9-11A for 300W panels)
Number of panels connected in series (increases voltage)
Number of panel strings in parallel (increases current)
System voltage (12V, 24V, or 48V)
Additional capacity for safety (typically 20-30%)

How to Use This Calculator

  1. Controller Type: Choose between MPPT and PWM controllers based on your needs.
  2. Panel Specifications: Enter your solar panel's Voc and Isc ratings from the datasheet.
  3. Array Configuration: Specify how many panels are connected in series and parallel.
  4. Battery Voltage: Enter your battery bank's nominal voltage.
  5. Safety Factor: Add a safety margin for temperature and future expansion.

Understanding the Results

  • Minimum Controller Rating: The minimum current rating needed for your charge controller.
  • Maximum Input Voltage: The maximum voltage your controller must handle.
  • Array Power: Total power output of your solar array.

Important Considerations:

  • MPPT controllers are recommended when panel voltage is significantly higher than battery voltage
  • PWM controllers require panel voltage to closely match battery charging voltage
  • Temperature affects voltage: allow extra headroom in cold climates
  • Consider future expansion when selecting controller size
  • Check manufacturer specifications for maximum input ratings

For optimal system performance, consult with a solar professional to verify calculations.