mppt vs pwm

brulaz wrote:

Salvo wrote:
No, not correct. Both the pwm and mppt controllers use pulse width modulation to control output voltage during absorb and float.

The 3048 manual discusses changing pulse widths during the maximum power point discussion. Do you understand what changing pulse widths means? It's pwm!!! The mppt controller uses pwm to achieve the maximum power point and it also uses pwm to achieve constant voltage output during absorb and float.
...

Again, forget output voltages. Look at panel voltages.

During the float or absorb stages the mppt controller maintains voltages on the panels that are different from the battery, whereas the pwm controller does not. They are obviously not doing the same thing.

The mppt controller is certainly using some form of pulse width modulation, but that doesn't make it's behaviour identical to a PWM controller during float or absorb states.

There is high frequency PWM and "low frequency" PWM. The "PWM" 12v controller uses low frequency PWM to "control" when it is stopping voltage from going any higher after it starts controlling.

I suppose the "MPPT" controller uses high frequency PWM to keep at the MPP during Bulk, and "low frequency" PWM during Absorb and Float same as a "PWM" controller does---but I don't know.

Wiki says there are a number of ways to do MPPT. One is to fiddle with panel voltage to find which voltage creates the most power.