Originally Posted by Cryoman
Thanks all. I found the panel Keystone used and you can only get it through Keystone.. the Keystone panel has an open voltage of 40 volts. The Renology panel open voltage is 27 volts. Does this make a difference when paralleling panels?
I'd say no. The Voc is, to me, more of a safety thing than a performance thing. For one thing, your solar system is not going to be "no load" in use.
Your total Voc must be less than the maximum solar voltage allowed by the charge controller.
So if you are going to parallel them, your Voc would be 33.5 volts. I'm still figuring this stuff out, but I believe that means you wouldn't have to change out your solar charge controller right away.
If you wire them in series your Voc would be 67 volts, which might exceed the rating of your solar charge controller.
edit: the maximum PV Voc for the MPPT 75/10 is 75V.