Jeffz
New Member
Can you combined solar panels with different output watts, voltage, and current?
Combining panels in series with different Imp (max power-point current) will limit you to the lowest current panel.
This is not desirable.
Combining panels in series with different Vmp (max power-point voltage) is ok (as long as the voltages aren’t too far off to cause damage).
The voltages add.
Combining panels in parallel with different Imp is ok, currents will add if the voltages are close.
Combining panels in parallel with very different Vmp (> 5%) should be avoided because the MPPT voltage selected will be sub-optimal.
Similar answers for Isc (short circuit current), and Voc (open circuit voltage).
as long as the voltages aren’t too far off to cause damage
Wow, 72.9V is really high!I have 11 panels of 355W (Vmpp = 34.7V, Imp = 10.25A) left over.
And also 9 panels of 425W (Vmpp = 72.9V, Imp = 5.83A).
Would probably be ok. My combinations have always been less than 2%, so I can’t say for sure.Could I take 10 of the first and parallel them with 5 of the second?
First string would be 347V and second string 364.5V
364.5 / 347 = 1.0504 so just at your 5% rule of thumb.
I’d be concerned, maybe others here have done it.Since the Vmpp is so drastically different, I don't think I can combine them in one string.
I think it would be the excess current going through the bypass diodes on the higher voltage panel if it is badly shaded.what damage exactly could or would happen if I were to combine 3 panels with Vmpp 72.V and 3 with Vmpp = 34.7V?
I assume the damage would be to the lower voltage panel?
600V system voltage for residential, 1000V system voltage for commercial.Surprisingly, the 355W panels have a max string voltage of 1000V and the 425W panels a max string voltage of 600V.
I was sorta in the same boat sorta as panels change through the years …….I chose to just go with a different SCC for each group of different panels and join them at my bussbars..that way they are all converted by the SCC to the proper programmed setting to work with each other…Thank you.
In my signature block, there’s a link to mixing and matching panels that will give you an idea of loss with math to back it up. Also goes over series, parallel, and series/parallel combinations.have 11 panels of 355W (Vmpp = 34.7V, Imp = 10.25A) left over.
And also 9 panels of 425W (Vmpp = 72.9V, Imp = 5.83A).
Could I take 10 of the first and parallel them with 5 of the second?
First string would be 347V and second string 364.5V
364.5 / 347 = 1.0504 so just at your 5% rule of thumb.
Since the Vmpp is so drastically different, I don't think I can combine them in one string.
I was sorta in the same boat sorta as panels change through the years …….I chose to just go with a different SCC for each group of different panels and join them at my bussbars
600V system voltage for residential, 1000V system voltage for commercial.
Yea your right about efforts plus it cost more…but after yer done it does work well…plus if a CC goes south or a tree falls on it you can isolate it with a MRCB. without messing with other arrays…Yeah that would obviously work, but I am too lazy to run more wires (I already have some of them installed and looking to add to that string).
In my signature block, there’s a link to mixing and matching panels