Can I mix 2 different manufactures solar panels in the same charge controller?

[paulcheung]

Hi I have 2 set of 4 panels 250w connect to outback charge controller. if i want to add 4 more panels to the charge controller, can I get 4 of the 235w panels? consider the 250w panels ARE NOT give me the wattage they claim? my other 235w panels are perform much better in another charge controller.

Thank you.

[inetdog]

Hi I have 2 set of 4 panels 250w connect to outback charge controller. if i want to add 4 more panels to the charge controller, can I get 4 of the 235w panels? consider the 250w panels ARE NOT give me the wattage they claim? my other 235w panels are perform much better in another charge controller.

Thank you.

If the two sets of panels have the same Vmp rating within about 10% you can put get by putting them in parallel to the same CC.
If they have the same Imp within 10% you can put them in series to the same CC. But you will not get the maximum amount of power from either set (maybe 5% less than the sum of the two sets.)
Any other matchup, as well as partial shading in either array, will require two MPPT inputs on one CC or else two CCs.

[paulcheung]

If the two have more than 10% different would it be ok if I am ok with the inefficiency? would it cause any damage to any part?

Thank you.

[inetdog]

If the two have more than 10% different would it be ok if I am ok with the inefficiency? would it cause any damage to any part?

Thank you.

I do not think it would cause damage to anything, but if the voltage difference is more than 15% you are in the area where the Vmp of one string might be above the Voc of the other string. With that much of a difference, the lower voltage panels may not contribute anything at all (depending on the details of the MPPT algorithm used.)

If the Imp difference is more than 20% or so, then if you mix the two types of panels in equal numbers there is a good chance that you could drive the low current panels to the point where their bypass diodes were activated and you might not get any contribution at all from them in that case either. And the higher current of the larger panels could actually damage the bypass diodes in the smaller panels, especially on a hot day.

What it amounts to is that outside the 10% range you really need to look carefully at the exact numbers to see whether there will be any point in trying to combine them into one input.

[paulcheung]

Thanks. Here is the specs for the panels

old panels are 8 of them connected in 2 set of 4 in series 2x4. I want to put the 4 new panels in series 1x4 to connect to the same CC (outback 60 amp mppt)

Pmax old 250 watts new 240 watts.
Vmp old 29.8 volts new 30.89 volts

IMP old 8.4 amps new 7.77 amps
Voc old 38.3 volts new 37.35 volts

Isc old 8.9 amps new 8.38 amps.



Can these panels be safe to put together in one CC 3 sets of 4 series?

Thanks again