MPPT Vs PWM Charge Controller

Charge controllers are a critical piece of hardware that is sits between your panels and your batteries.

If you are using a PWM (Pulse Width Modulated) charge controller then already your single easiest upgrade to an off grid solar application is just that. Investing in a quality MPPT (Maximum Power Point Tracking) can increase power from your panels up to 100% more.

PWM works by throttling excess voltage coming into your panel. If your panels are at 22v and your batteries are at 12v then an excess 10v will not be used, hence 10 watts for every amp is wasted (A∙V=W), that is equivalent to a 45% loss!

If you have an MPPT controller and your panels are at 22v (pressure) and producing 1 amp (flow) then we have 22 watts coming into the charge controller. The MPPT reduces the voltage but unlike its PWM counterpart, it will increase the amperage proportionally. The MPPT charger will output 12v but at 1.8 amps. Now we have 22 watts coming in at high voltage and 22 watts going out at low voltage, efficient!

Another great benefit of having an MPPT charger is that we can crank up the panel voltages as high as 100 volts, which not only increases efficiency but greatly reduces wire diameter. MPPT chargers are rated with two number 75/15 for example means that it can handle a maximum of 75 volts and a maximum of 15 amps.

If your charge controller can only handle 15 amps that means with a 12 volt battery we can only utilize 180 watts worth of solar, with a 24 volt battery we can utilize 360 watts of solar, and with 48 volt batteries we can get 720 watts of solar from the same charge controller.