Test Method PWM vs MPPT ?
I might get a chance to compare MPPT with my PWM on the set of two 100w panels. I get 12.6 (Isc) now with PWM so that is the "standard" I was thinking of a quick connect set-up to swap controllers...
Forum Discussion
BFL
It should be a interesting test but will be gear specific. Your test will be good for people with 12v panels to decide if getting MPPT will be an improvement over PWM. use a different MPPT controller and you may get different results.
While I was camping there would be times that PWM would have done more for me than MPPT even with my high voltage panel. Yes the max output I saw in PWM was 13a vs the 16a I saw in MPPT but MPPT requires higher voltages. As the light drops so does the voltage. So if my battery was low and it was heavy overcast the Eco-worthy would get stuck in MPPT at 1.78a where the PWM modes (absorb and float) could produce two or three times the amps in the same lighting conditions. In PWM I got 4a in the rain, not much but better than 1.78a.
Of my two panels, one poly, one mono, the mono's voltage is effected more by light lose than the poly. Even in overcast situations the poly stays up in the 33+ volts range where the mono will drop to the 28-29v range. That kills MPPT.
Does the voltage of 12v panels stay up as light drops and you only lose amps? If so the MPPT function may act different than it does on my high voltage panels.
for testing I have used a inverter with a 100w and a 60w bulb to keep the batteries voltage down, the 200w coffee pot did well to because it was so close to the wattage of my panel. The battery voltage stayed at 13.4v while the controller was in MPPT kicking out 212w.
The interesting test would be if you could get your hands on a pair of high voltage 100w panels or even a 200w 24v panel on MPPT and compare that to your 200w of 12v panels on PWM.
It should be a interesting test but will be gear specific. Your test will be good for people with 12v panels to decide if getting MPPT will be an improvement over PWM. use a different MPPT controller and you may get different results.
While I was camping there would be times that PWM would have done more for me than MPPT even with my high voltage panel. Yes the max output I saw in PWM was 13a vs the 16a I saw in MPPT but MPPT requires higher voltages. As the light drops so does the voltage. So if my battery was low and it was heavy overcast the Eco-worthy would get stuck in MPPT at 1.78a where the PWM modes (absorb and float) could produce two or three times the amps in the same lighting conditions. In PWM I got 4a in the rain, not much but better than 1.78a.
Of my two panels, one poly, one mono, the mono's voltage is effected more by light lose than the poly. Even in overcast situations the poly stays up in the 33+ volts range where the mono will drop to the 28-29v range. That kills MPPT.
Does the voltage of 12v panels stay up as light drops and you only lose amps? If so the MPPT function may act different than it does on my high voltage panels.
for testing I have used a inverter with a 100w and a 60w bulb to keep the batteries voltage down, the 200w coffee pot did well to because it was so close to the wattage of my panel. The battery voltage stayed at 13.4v while the controller was in MPPT kicking out 212w.
The interesting test would be if you could get your hands on a pair of high voltage 100w panels or even a 200w 24v panel on MPPT and compare that to your 200w of 12v panels on PWM.
