Any opinions on combining different voltage panel strings?

[Bossrox]

I've been wondering as an example, what if I had a string of panels that was putting out 145v & combining it with a string doing 120v. It would seem to me the stronger string would shoulder the majority of work energy until knocked down enough for the other string to contribute. This is the way batteries react so I'm guessing solar panels would be the same? Any opinions?

 

[sunshine_eggo]

Lots of conversation on this topic.

Important that Vmp values are within 5-10%, and you should expect a performance hit of about the same % from both arrays.

They will operate somewhere in the middle, but likely closer to the lower voltage.

For a 21% difference per your example, I would not expect good performance at all. In fact, there's a risk the lower voltage string might act as a short circuit path for the higher voltage string thus ensuring your MPPT doesn't see any current/voltage at all. For such an extreme difference, blocking diodes are required.

 

[timselectric]

Any opinions?

Just don't

 

[pollenface]

My opinion is to use a separate charge controller for each string.

 

[sirslayer]

Different voltage equals different problems later on

 

[Bossrox]

My opinion is to use a separate charge controller for each string.

That makes better sense after seeing the 1st reply.