I'm planning to set up my 48V solar system with four 200W 24V panels, but I'm unsure about the best wiring approach. Should I connect all the panels in series, which would yield about 96V total, if my MPPT can handle that kind of input? I know the input voltage needs to be higher than the battery voltage. What would be the optimal voltage configuration for feeding my 48V MPPT? Currently, I have one 48V 100Ah lithium battery but plan to add another one and a 4000W inverter soon. Any advice would be appreciated!
4 Answers
A 2P2S setup is probably your best bet, connecting two panels in series and then running two of those strings in parallel. This keeps your voltage in a good range for most MPPTs (about 64-76 volts), plus it offers some safety against shading since a shading issue on one panel won't affect the entire string. And remember, those panels output around 10V higher than their rated voltage to properly charge your 48V system!
You can run both sets of panels to one controller by connecting them together; no need for two separate controllers!
Going for all four panels in series is usually the best bet as long as your MPPT can take it. However, remember that "24V" panels typically output more like 30V at peak and around 36V open circuit. So, when you string four together, you might hit voltages like 142V! If you're worried about shading affecting output, consider a 2S2P setup, which can help isolate issues if one panel is blocked by shade.
Are you considering this charge controller? https://a.co/d/etOD8dj. If I go with the 2S2P setup, will I need two controllers, or can I just connect the two strings together at one controller?
If you wire in a 2S2P configuration, you can connect both strings to a single charge controller without needing separate controllers!
Definitely check the specs for your panels first. Using the Victron MPPT calculator can help you understand how different configurations work with your specific setup. If you’re in a colder area, remember that colder temperatures can raise voltage output, so you don't want to exceed your controller's limits. Plus, wiring them in series could reduce line loss by allowing you to use smaller gauge wire—just keep shading penalties in mind!
It's super important to know the open circuit voltage of your panels, which could be higher than the rated voltage. For example, my "24V" panels can hit about 44V open circuit. I connect two in series and have seen around 90V during summer charging times. Just be sure to pick an MPPT that can handle the input and optimize your series/parallel arrangement for reduced cable losses!
If I go with this wiring style, will I need two charge controllers, or can I just run those cables to one and "Y" them together?