charging batteries with different v panels

jimbob01

i want to put panels with vmp 31v in parallel with panels of 21v vmp in to a pwm c60 xantrex cc to charge my batteries temporarily until i get my mppt set up alongside it?
the c60 has an input voltage of 55v
will i just get the reduced current expected with a pwm cc or are there any other effects to concern myself about?
thanks jim

Cariboocoot

Re: charging batteries with different v panels

You'll get reduced power as solar panels try to always produce their rated current but allow the Voltage to fluctuate.

I think you may have Vmp and Voc confused on at least one of those panel types as Vmp 21 isn't normal. Vmp 31 is kind of odd too.

Depending on the exact specs, the lower Voltage panels will be "pulled up a little" in Voltage causing a slight drop in their current output and the higher Voltage panels will be pulled down although their current will remain largely unaffected. In general no harm can come from it.

There can be issues in some instances where the higher Voltage panel can feed back through the lower one, but there usually is some quite substantial Voltage difference required for this to occur.