MPPT vs PWM

Definition

A PWM controller connects the panel almost directly to the battery, so harvest is limited by battery voltage. An MPPT controller tracks the panel’s maximum-power voltage and converts extra volts into extra charge current (P = V × I, minus conversion loss). MPPT is worth it when module Vmp sits well above battery voltage (for example a 60-cell grid panel on a 12 V bank). PWM can be adequate when Vmp is already close to the battery. Controller output current is about array watts ÷ battery volts, not module Isc.

Calculators that use this

• inverters

  PWM vs MPPT Efficiency & Yield Comparison

  Compare daily watt-hours from a PWM charge controller versus MPPT when panel Vmp is above battery voltage.

• inverters

  MPPT Charge Controller Sizer

  Size an MPPT charge controller from array watts and battery voltage, with 20% current headroom and Voc margin.

• solar panels

  Solar Array Sizer

  Estimate how many solar panels you need from daily watt-hours, panel watts and peak sun hours, including a realistic derate.