Am I mistaken, or is the calculator wrong?
I used the calculator to determine the size of my MPPT. My solar panels have the following specifications, and I used two units of this model in the calculation, resulting in an indicated MPPT of 100/30 for my 24V system:
- Pmax = 405
- Open circuit voltage (Voc/V) = 37.15
- Short Circuit current (Isc/A) = 13.78
- Vmp = 31.18
- Imp/A = 12.99
I connected both panels in series, so the formula for my voltage is 37.15 + 37.15 = 74.3, and the current remains the same at 13.78 A. However, when I use the calculator again and input that I want to connect 2 strings in parallel, the calculator suggests upgrading to an MPPT 100/50 model.
But why? Doesn't the voltage remain the same, 74.3 Volt , and the current becomes 13.78 + 13.78 = 27.56 A? Shouldn't I still be able to use my MPPT 100/30 with 2 series + 2 strings, or why does the calculator recommend upgrading to 100/50?"