mppt or pwm An opinion from Victron

Golden_HVAC wrote:
I wonder what would have happened if they had compared "No controller" results with the controller results?

In my older RV, I had a PWM controller - 15 amp Mark III I think, and I installed a 3 way on-off-on switch with power from the panels going to the common terminal, and one going to the factory input for the PWM and the other going directly to the amp meter output. So I could switch to bypass the controller, and usually get an extra 1/4 - 1/2 amp according to the cheap meter on the controller. While camping, I could switch to the output, and get an extra couple of amp hours daily from the panels.

Now I have a 300 watt system and Solarbooste 50 amp MPPT controller. I always have wondered if the amperage will increase or not when bypassing the controller. At a lower output voltage, solar panels will increase it's amperage flow. So with a MPPT controller changing the output volts higher in order to convert it to a higher amperage, it might be slowing the charge rate.. .

Fred.

With PWM like you had, you get the same amps direct or through the controller. What you can do is once the controller starts controlling and it has a non-adjustable high set point of say 14.3v like some do, is switch to direct and let the battery voltage keep climbing past 14.3.

You can reconnect the controller when battery voltage reaches your target like 14.9. That sounds like what you did to get some extra AH in.

With MPPT that would not help the same way unless your controller did not have the adjustable set point and it was fixed low at 14.3.

The panel-direct will only get you panel Isc and with 24v panels that is "half" what it is with 12v panels. Normally the MPPT controller will be doing more amps to the battery than panel Isc, so you would lose by going direct, unlike with PWM where it is the same amps.

Now when you get to Vabs high set point on the MPPT, the controller drops out of MPPT and goes PWM, but it still bucks the voltage so you can get more than Isc amps even though in PWM.

At some point if you want to go higher in battery voltage than the controller adjustable set-point will go to, you can go direct and the battery voltage will go higher till you stop it by reconnecting the controller. This might be useful to equalize the batts if the controller does not have an equalize setting.