Solar Panel Voc-MPPT?
Wondering if there is any relationship between measured Voc and MPPT performance with a 24v panel. My 12v panel has a Voc rating of 21.9 and Isc of 8.2, but I often see 8.2ish when Voc is only 20....
Forum Discussion
Shadow
Like you I bought my panels before I understood what I was buying and ended up having to buy a MPPT controller because of it. It worked out great but for a while there I considered selling the panels off and buying a 12v system instead if only to save on the cost of the controller.
70v, my controller can only handle 42v, otherwise I could get some panels really cheap. One guy has been trying to sell some 110w/ 238v panels for quite a while now.
I agree that for some a single high voltage panel will be better. There was a comparison of 12v vs 24v panels cost and foot print per watt. The high voltage did better in footprint. Panels seem to be getting smaller too. My 220w mono is noticeably smaller than my 230w poly, and there now is a 270w the same size as my 220w. That's a lot of power for someone that's not running high inverter loads.
As far as the MPPT/ PWM debate, I think there are to many variables to allow it to become a limiting factor at the outset of designing a system. What panels are available and fit your needs may decide it for you.
Like you I bought my panels before I understood what I was buying and ended up having to buy a MPPT controller because of it. It worked out great but for a while there I considered selling the panels off and buying a 12v system instead if only to save on the cost of the controller.
70v, my controller can only handle 42v, otherwise I could get some panels really cheap. One guy has been trying to sell some 110w/ 238v panels for quite a while now.
I agree that for some a single high voltage panel will be better. There was a comparison of 12v vs 24v panels cost and foot print per watt. The high voltage did better in footprint. Panels seem to be getting smaller too. My 220w mono is noticeably smaller than my 230w poly, and there now is a 270w the same size as my 220w. That's a lot of power for someone that's not running high inverter loads.
As far as the MPPT/ PWM debate, I think there are to many variables to allow it to become a limiting factor at the outset of designing a system. What panels are available and fit your needs may decide it for you.
