Claimed MPPT

ShadowcatcherShadowcatcher Solar Expert Posts: 228 ✭✭✭
Is their an easy way to check if a claimed MPPT controller, is in fact? Mine is a Morningstar and is, but I know some who bought one that claims it is but...
Would the wave/pulse form tell you?


  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: Claimed MPPT

    Here is a thread about a claimed MPPT charge controller--Picture of guts a page or two into the thread.

    Basically, if there are no large inductors inside--it probably is not a MPPT controller.

    The problem using a meter is that with relatively charged battery bank, both MPPT and PWM controllers have very similar behavior.

    It is only with a discharged battery bank (less than 90-80%?) that the MPPT mode "kicks in"...

    With a PWM controller charging at 100% current, the voltage of the solar array input will be almost the same as the battery charging output (with in 1 volt or so).

    With a MPPT charge controller at 100% output, the input voltage should be around Vmp-array and not tracking the battery charging voltage.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • icarusicarus Solar Expert Posts: 5,433 ✭✭✭✭
    Re: Claimed MPPT

    Unless you want to and can take one apart, the way to tell is to meter voltage/current input vs voltage/current output. A Shunt and meter on both sides of the controller will do that.

    Some MPPT controllers have on board metering that does this. The Rogue for example constantly displays input voltage/current/wattage and output voltage/current/wattage. I compare the output to the Trimetric and it is very close on average.

  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Claimed MPPT

    Another easy way is to check the voltage at the input of the CC, and it should be higher than the battery voltage, especially on a cold day. If that voltage is substantially higher, then the MPPT CC should (if in Bulk mode) be producing more amps to the battery, than what is coming in from the panels. This is easily checked with a DC clamp meter.
    Rough example, if the panels are putting out 5 amps @ 24 volts, you could see perhaps 8 or 9 amps @ 13 volts going to the battery.
    If it's not an MPPT controller, you won't see that increase in amps.
  • WindsunWindsun Solar Expert Posts: 1,164 ✭✭
    Re: Claimed MPPT

    If you have higher voltage panels, it is pretty easy if the controller has a meter or you have a good digital meter.

    Just measure or read the incoming amps x volts coming from the panels into the controller and compare it to the same thing coming out, going to the batteries and system.

    Amps x volts = watts, so typically output watts should be around 95% to 98% of input for an MPPT controller.
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