More MPPT Confusion and Question
Still trying to understand my MPPT set-up and what would be the effect of changing things a bit. My 230w (30.0 Vmp x 7.7 Imp) poly panel has a Vmp of 30.0v with a measurement tolerance of +/- 3% S...
Forum Discussion
I am confused as to what makes Salvo think there is something wrong with the controller. I think he got mixed up reading my pile of numbers.
He thinks there is a "discrepancy" because he says the MPPT is not out-performing what PWM could do in the case I gave by 5-10%
Mine was typically 15.5a MPPT vs 14.5a PWM so about 1/14.5 = 6.9% in the Spring. That was with the 44C panel and its estimated 7% loss from that much heating.
Then he suggests that "discrepancy" could be because the irradiance was lower. In fact, if that were lower then the input would be less and that would make the controller's output look better! Oh well. It is easy to get mixed up sometimes reading all this stuff.
I can't take any more measurements till April so I am still hoping somebody else with solar working now can take measurements as outlined above so we can see what might be "normal" to compare with what I got.
He thinks there is a "discrepancy" because he says the MPPT is not out-performing what PWM could do in the case I gave by 5-10%
Mine was typically 15.5a MPPT vs 14.5a PWM so about 1/14.5 = 6.9% in the Spring. That was with the 44C panel and its estimated 7% loss from that much heating.
Then he suggests that "discrepancy" could be because the irradiance was lower. In fact, if that were lower then the input would be less and that would make the controller's output look better! Oh well. It is easy to get mixed up sometimes reading all this stuff.
I can't take any more measurements till April so I am still hoping somebody else with solar working now can take measurements as outlined above so we can see what might be "normal" to compare with what I got.
Salvo wrote:
There's three possibilities for this discrepancy.
1. Irradiance fluctuates. You could be measuring mppt current when irradiance was lower.
2. Measurement error.
3. Your mppt controller is sub par.
If everything is working correctly, you should see 5 to 10% more current with mppt.BFL13 wrote:
Salvo that is part of the big puzzle to me. The Isc was over the rated Isc of 8.3 so to me that means the panel is at least at STC for irradiance, allowing for the high temperature raising Isc but lowering Voc.
I just figure if the Isc is over its rating that means the insolation is ok, and any losses are from something else. No?
