Wow... I've read a LOT of great info on this site. But there are a lot of numbers and my pea-sized brain still has a couple of questions. Here's what I know: (Please correct anything I've misunderstood!)
* Panels in SERIES Voltages add, and current remains the same, while for panels in PARALLEL their Amps add together and voltages remain the same.
* Battery charging begins once the panel Voltage is more than 5V above the voltage of the battery.
* SmartSolar controllers can handle more amps from the panel(s) than indicated by their model numbers - they just don't push more than that charge into the battery above the limit (eg my SmartSolar 75/15 will limit Amps into the battery to 15A
* Voltage indicated by the model number (eg 75V for my SmartSolar75/15) is a hard limit that will damage the controller if exceeded by the total open circuit voltage stated on the panel(s).
I already have a SmartSolar 75/15 and one 12V 150W panel with these specs:
VOC 22.3V and Vmp 17.9V with max current 8.73A
I currently have a 21V 150Ah AGM battery but plan on replacing it with a 200Ah LiFePO4
I have a second panel the same that is not connected, and the possibility of a separate 310W panel also. Here are the questions:
Assuming I don't want to buy another Charge Controller - 1. If I connect the second 150W panel in Series will I start charging earlier in the day or if its cloudy or partially shaded because the voltages are added and therefore higher earlier in the day than if they were in Parallel?
2. In series voltages add. So 2 panels at Voc 22.3 x 2 = 44.6V This is under the 75Vlimit... any problem with this aspect?
3. In Series the current is the same - since the panels put out 8.73A my 15 A controller wont be close to the max it can push to the battery. Is this a waste of the potential of the panels?
3b. Would It be smarter to put the same 2 panels in parallel, accept that they wont start charging as early in the day or as often in partial shade or cloud but get more amps (which might on rare occasions when everything is perfect exceed 15A since 2 x 8.73A = 17.46A, and therefor be limited to 15 A by the controller)?
4. If i were to replace the 150W panel with a singe 310W 12V ( Voc 40.5V, Imp 9.4A) panel would I get similar results to the total 300W of a 2-panel in parallel setup?
I know there is fair bit here. I hope your answers can not only educate me but also help clarify for future readers who, like me, spent a long time trying to understand this stuff by amalgamating knowledge from previous posts...