PWM (pulse width modulation) charge controllers are simpler charge controllers compared to MPPT controllers. A PWM controller uses very fast switching, many times per second, to control the current flow from a PV panel to a battery for charging. PWM controllers work best when the nominal voltage of a solar array matches the nominal voltage of a battery bank.
MPPT (maximum power point tracking) controllers use conversion technology for charging. An MPPT controller does not require the solar panels to be of the same nominal voltage as the battery bank. It can convert PV power at a high voltage to charge power at a lower voltage for a battery bank. MPPT controllers can be up to 30% more efficient than PWM, but they are often more expensive and unnecessary for small systems.
Read our document “Comparing PWM & MPPT Charge Controllers” to learn more.