I'm planning to build a DIY solar power system and need some advice on choosing a controller. I'm considering the Victron 100/20. Right now, I have one solar panel that outputs 50V with no load and can deliver about 10 amps under good sunlight. I'm planning to get a second panel like this one. Additionally, I have a 100Ah 12V battery, but I'm looking to expand my battery capacity as well. So, if I add another solar panel, should I connect them in series or parallel? Also, will the controller handle this setup, or am I pushing it to its limits?
2 Answers
Yeah, if your panel provides 50V open-circuit, going series could be too risky, nearing the 100V max limit. Just keep in mind that for a single 12V battery, you're capped around 290W of power. If you switch to a 24V system later, you'd double that capacity. Your current panel seems to be around 400W based on the specs, so the controller is really where you'll hit the limits.
You should connect the panels in parallel since the open-circuit voltage (Voc) of those two would be too close to the controller's max. Be careful with that!
True, but keep in mind that the amperage could be close to the controller's max as well if you parallel them. The second number in that 100/20 model refers to the max current it can handle at 12V, so you might end up getting less than the peak current your panels could put out. It might be worth looking into a more powerful controller, like a 150/50, or going for a hybrid inverter capable of handling higher voltages.