I'm considering purchasing the Victron RS450-100 charge controller, which has a spec that claims a maximum charge current of 100A. However, it also states that the two MPPT trackers can only handle 16A each for normal operation and 20A for short-circuit. I'm trying to understand how the charge controller can deliver the maximum 100A using just these two 16A trackers. I have 12 Sharp Bifacial panels rated at 580W each, with a voltage open circuit (VOC) of 52.55V and a short circuit current (ISC) of 14.03A. I plan to wire them in series, creating a string of 6 panels per tracker (which gives me 315.3V, well within the controller's input range of 120-450V). How can I calculate the actual charge current I can expect, and how long will it take to fully charge my batteries?
2 Answers
You're right about the wattage; with 6960W from your panels, you're looking at around 145A at 48V, which means you're almost 50% over-paneling. This should help you reach those 100A output limits. You've got a nice MPPT setup—keeping the string voltage under 250V is wise. Plus, using two strings of three panels each for higher peak outputs at lower costs is a smart move. Just remember that charging time isn't linear, and the Victron uses a specific charging profile that starts with high current and then shifts to constant voltage, making it faster than lead-acid charging, though it will slow down once you hit about 80% charge.
Exactly! And if you're looking for specific charge times, you can use the Victron MPPT calculator to estimate it better based on your battery capacity.
The key thing to remember is that the 450V is the maximum input voltage for the charge controller, while the 100A is the output maximum current. Essentially, the MPPTs act as DC-DC converters. For example, 300V at 10A can be converted to approximately 58.4V at 51A after the conversion process. You can figure out your actual charge voltage by doing a quick calculation of the input wattage divided by the battery charge voltage.
Got it, that helps clarify things! So, if I understand correctly, the voltage drop is like the magic that allows for higher current output?
Thanks for breaking that down! So I shouldn't worry too much about the over-paneling, just need to monitor peak outputs?