I'm looking to set up three 450W solar panels in series to charge a 12V battery setup. Here are the panel specs: each panel has a voltage of 41.5V at Pmax and a current of 10.85A. The open-circuit voltage is 49.3V, and the short-circuit current is 11.60A. What size charge controller would I need for this configuration? Also, if I were to connect the panels in parallel instead due to tree shade affecting sunlight in the afternoon, how would that change the requirements? The panels would get decent direct sunlight for the first 2 to 3 hours in the morning, unless it's cloudy. Thanks for any help!
3 Answers
Go with series wiring and an MPPT charge controller that can handle up to 200 volts. However, consider how your panels will be affected by that afternoon shade. If all three panels get shaded at once, you might end up losing a lot of power. If they shade one at a time, keeping them in series is fine since you’ll still be generating some power. Just think about how that afternoon sun can impact overall energy production—sometimes it’s worth keeping some panels in parallel!
If you have devices that aren’t all 12 volts, you might want to consider a 48V battery bank instead. This way, the cables can stay smaller and more manageable between the charge controller and the battery, which is always a plus for installation.
Typically, you'd want to wire the panels in series. However, keep in mind that if you do that, your charge controller needs to handle a peak voltage of around 125V (41.5V * 3). But remember, the max voltage is actually 49.3V, which means you'll be looking at around 180V for safety under cold conditions if you account for that extra 15-20%. Also, the combined current means you’d need a controller that can manage 40 amps. It’s crucial to factor in those specs when choosing the controller!
Actually, the peak voltage you need to calculate for is 49.3V, so when you take into account the shade and bad conditions, it’s smart to design for the worst case. Regardless, make sure whatever you choose can handle those higher voltage levels.