sunshine_eggo
Happy Breffast!
LOL... do you even know what the strawman fallacy is?
answer the question (same question twice):
Mismatched Solar Panels for Van Build
- Thread starter b33son
- Start date
LOL... do you even know what the strawman fallacy is?
answer the question (same question twice):
Ok back to interesting problems of mis-matched panels…
One other idea. Add a mppt.
Mppt#1 100/50: put the two100w panels in parallel- then put them in series with the 200w panel. Design so if you ground mount any they go on this array.
Mppt#2 put right side 55w + 35w panels in parallel… put left side 55w+ 35w panels in parallel then put those two sides together in series- use a small Victron 75/15 for this mppt (it is much smaller than the 100/50).
The mppt#2 may help with shade because either left or right may have shade - so half the panels on this array should always have sun and that should not affect the big panels.
Math…
Mppt#1 5.13a +5.13a= 10.26a 19.5v
Plus in series will be 9.8a and 19.5v +20.4v=39.9v
39.9v * 9.8a = 391w
Mppt#2 2.94a + 1.96a = 4.9a and 17.9v
In series 4.9a and 17.9v + 17.9v=35.8v
4.9a * 35.8v = 175 w
391w + 175w = 566w for the system. Out of 580w max - only a 14w penalty - Wow!
SunshineEggo’s plan was 526w
This one is 566w - is 40w worth the space for a mppt 75/15? A 7.6% boost. I also think this plan does better with the roof shade.
This is why I like these mid-matched problems - sometimes there is a better solution if you look at it slightly differently.
FYI - you probably already know that if you have three or more panels in parallel- each string need a fuse (there are MC4 fuses for that).
Good Luck and let us know how it turns out.
One other idea. Add a mppt.
Mppt#1 100/50: put the two100w panels in parallel- then put them in series with the 200w panel. Design so if you ground mount any they go on this array.
Mppt#2 put right side 55w + 35w panels in parallel… put left side 55w+ 35w panels in parallel then put those two sides together in series- use a small Victron 75/15 for this mppt (it is much smaller than the 100/50).
The mppt#2 may help with shade because either left or right may have shade - so half the panels on this array should always have sun and that should not affect the big panels.
Math…
Mppt#1 5.13a +5.13a= 10.26a 19.5v
Plus in series will be 9.8a and 19.5v +20.4v=39.9v
39.9v * 9.8a = 391w
Mppt#2 2.94a + 1.96a = 4.9a and 17.9v
In series 4.9a and 17.9v + 17.9v=35.8v
4.9a * 35.8v = 175 w
391w + 175w = 566w for the system. Out of 580w max - only a 14w penalty - Wow!
SunshineEggo’s plan was 526w
This one is 566w - is 40w worth the space for a mppt 75/15? A 7.6% boost. I also think this plan does better with the roof shade.
This is why I like these mid-matched problems - sometimes there is a better solution if you look at it slightly differently.
FYI - you probably already know that if you have three or more panels in parallel- each string need a fuse (there are MC4 fuses for that).
Good Luck and let us know how it turns out.
Last edited:
featherlite
Solar Enthusiast
I think you meant more than two panels (i.e., three or more panels).
Thanks for the catch… typo between the brain and the finger…. I fixed the above statement to be correct.
