mppt or pwm An opinion from Victron
Hi all, Victron, which makes high quality equipment, has charge controllers. At the end of an overview they give their description of the differences between PWM and MPPT. They do not support it wi...
Forum Discussion
PT, I still don't know what "panel voltage" you mean. It is Voc when not connected.
When connected to a PWM panel voltage is battery voltage, when connected to an MPPT panel voltage is Vmp (both ignoring Vdrop)
What I see at my temperature range while camping is that the panel Isc does not go down with temperature so I get full Isc along the IV curve all season. Voc goes down with higher temp but I don't care, the amps are still up because Isc actually rises with higher temp.
My 130w panel was usually at 20.3Voc at 25C ambient (never took panel temp back then) of 21.9 rated. But Isc was 8.3 vs 8.2. ( I remember posting about my "missing volt" when I noticed that 20.3 and was assured by the guys here it was just temperature effect)
Meanwhile the MPPT depends on watts to create amps from and those watts drop with higher temp, so pretty soon the amps it can make are less than what the PWM is doing at Isc.
So in April and May my MPPT does better than PWM but the rest of the season June-August PWM does better, then for September they are about equal. I expect in October on, MPPT would get back to being better, but on 1st October my solar gets put away in the garage till next April. I don't bother with solar in the dark part of the year camping in the woods.
On the 12v in parallel with MPPT question, it might be that the Voc limit for the controller in question forbids putting so many 22Voc panels in series. As everyone knows, you could do series strings to under the Voc limit, then put the strings in parallel.
Mena, you can still put the several smaller panels that will fit on the roof in series to get more voltage and use MPPT. I would be looking at temperature scenarios for MPPT vs PWM. Your hot places make your PWM choice a good one IMO.
I don't care about having to use fatter wire in my situation. A stick house with many, many panels is different for wiring factor.
When connected to a PWM panel voltage is battery voltage, when connected to an MPPT panel voltage is Vmp (both ignoring Vdrop)
What I see at my temperature range while camping is that the panel Isc does not go down with temperature so I get full Isc along the IV curve all season. Voc goes down with higher temp but I don't care, the amps are still up because Isc actually rises with higher temp.
My 130w panel was usually at 20.3Voc at 25C ambient (never took panel temp back then) of 21.9 rated. But Isc was 8.3 vs 8.2. ( I remember posting about my "missing volt" when I noticed that 20.3 and was assured by the guys here it was just temperature effect)
Meanwhile the MPPT depends on watts to create amps from and those watts drop with higher temp, so pretty soon the amps it can make are less than what the PWM is doing at Isc.
So in April and May my MPPT does better than PWM but the rest of the season June-August PWM does better, then for September they are about equal. I expect in October on, MPPT would get back to being better, but on 1st October my solar gets put away in the garage till next April. I don't bother with solar in the dark part of the year camping in the woods.
On the 12v in parallel with MPPT question, it might be that the Voc limit for the controller in question forbids putting so many 22Voc panels in series. As everyone knows, you could do series strings to under the Voc limit, then put the strings in parallel.
Mena, you can still put the several smaller panels that will fit on the roof in series to get more voltage and use MPPT. I would be looking at temperature scenarios for MPPT vs PWM. Your hot places make your PWM choice a good one IMO.
I don't care about having to use fatter wire in my situation. A stick house with many, many panels is different for wiring factor.
