Solar-Panel to Controller Loss
Much has been made of the lower losses on the panel to controller path with MPPT because the amps are less. So once you have your loss measured, how valuable is it to improve on that if you don't lik...
Forum Discussion
I cleaned up the path somewhat based on the results of the Salvo check as posted earlier, was:
P-A Pos 0.07, Neg 0.15 = 0.22
P-B Pos 0.14, Neg 0.21 = 0.35
P-C Pos 0.23, Neg 0.29 = 0.52
Now:
P-A Pos 0.06, Neg 0.07 = 0.13
P-C-Pos o.19, Neg 0.19 = 0.38
(eliminated section A-B and fixed neg at panel pigtail that was 0.15 before)
Can't do any more with connections. P-A is fat wire and A-C is thinner wire but not worth changing that.
Vmp at the panel end was 29.2 at the time of this check, so the loss is 0.38/29.2 = 1.3%
As noted earlier it doesn't make a lot of difference at the Imp of 8ish amps, but with a larger array it would. (Good point about that!)
Might also need to take this path R into account when choosing series vs parallel I suppose.
BTW I noted the panel temperature of the tilted up facing sun panel was 45C near the top and 41C near the bottom. (heat rises?) Thatmeans the cells nearer the top have lower voltage while all 60 cells are in series, so the voltage you get out of the panel pigtails is the result of that. Not a big deal, but might make you prop the panel up sideways instead of the long ways :)
P-A Pos 0.07, Neg 0.15 = 0.22
P-B Pos 0.14, Neg 0.21 = 0.35
P-C Pos 0.23, Neg 0.29 = 0.52
Now:
P-A Pos 0.06, Neg 0.07 = 0.13
P-C-Pos o.19, Neg 0.19 = 0.38
(eliminated section A-B and fixed neg at panel pigtail that was 0.15 before)
Can't do any more with connections. P-A is fat wire and A-C is thinner wire but not worth changing that.
Vmp at the panel end was 29.2 at the time of this check, so the loss is 0.38/29.2 = 1.3%
As noted earlier it doesn't make a lot of difference at the Imp of 8ish amps, but with a larger array it would. (Good point about that!)
Might also need to take this path R into account when choosing series vs parallel I suppose.
BTW I noted the panel temperature of the tilted up facing sun panel was 45C near the top and 41C near the bottom. (heat rises?) Thatmeans the cells nearer the top have lower voltage while all 60 cells are in series, so the voltage you get out of the panel pigtails is the result of that. Not a big deal, but might make you prop the panel up sideways instead of the long ways :)
