phemens wrote:
I have a total of 630 ah of batteries (3x 12v). My plan was to wire up 3 solar panels 1 existing 250w plus 2 new 300w panels) at 24v to a Victron Blue Solar 50A MPPT controller. I spoke to the guy selling me the panels, he tells me that my first limitation in the max wattage the batteries can accept from the controller at 12v (manual says 700w at 12v or 1400w at 24). After that point he says that the MPPT will cap the output anyways.
He says I’m better off putting 2 x 72 cell 335w panels on the Victron 50A MMPT (670w total) and adding a separate controller for the 250w panel wired separately to the batteries.Ã
Is this correct?
The batteries will accept 30% charging rate no problem, but not worth going higher than that ( except with certain batteries) So your 630AH bank can accept 190 amps no sweat.
However, the MPPT controller will cap its amps to its rated "size" in amps. Eg my Tracer 20 amper will do that and no more even if it is on a bigger panel (in watts) than it is rated for (260w)
So you need a 20 amper for that 250w you have now. Add a pair of 300s you need about 25 each? So that 50 amper looks about right.
So the guy is right that you need both controllers in parallel on the one big battery bank, but you will not go over what the bank will accept in total amps.
If the 335s are a good price and the 50 amper will do it, sounds good.
You can go a bit over on panel watts (as often recommended with MPPT) anyway, because most of the day you will be under the max watts and be getting more AH haul, but 250w over is way too much IMO.
