Hi.

I want to remove 3 x 250w panels from my 12 that I have and install some 12v led lights through the house. The question is.

1. What size mppt controller do I need to buy to charge 1 or 2 batteries.

2. Will the 3 x panels in series be to much or would I need less.

Much appreciated.

Daniel

 

Normally it works the other way around, need X amps to charge the battery bank, so get that controller with Y amount of panels on it, keeping the charge and load requirements in mind.

Flipping that around, the MPPT you need is based on the panel configuration, either parallel or series connected, to keep the volts below the max, and the amps within range.

Then from that you can then determine the right size MPPT to get.

Once that has been established then one knows the max charge amps you can get from the MPPT which in turn determines the size of battery bank to not under-charge it, with or without the load in play.

 

The panels are in series at the moment  x 3.

I would aim at a smaller 150W or 250W panel and a small MPPT. Three 250W panels would have the ability to charge at 50A - way more than one or two batteries could absorb unless they are serious >200Ah boykies.

Plus it they are in series you have a big panel battery voltage mismatch and if they are in parallel we now  talking slightly thicker cables (6mm2) and moderate amps.