Puzzeling thru a 12v to 24v solar upgrade

glennts wrote:
@2oldman "It may result in over-amperage. 325 x 3/13= 75a"

The panel output will be taken in by the 4210AN as 24V. The Tracer unit is designed for 1040w/24v ( @ 43a ). The panels will be 975w/24v (@40a). And this assumes a perfect world in which they hit the rated capacity.

Not sure you are clear on how that all works.

Your controller will set panel voltage at Vmp (panel specs) during the Bulk stage. Imp amps will depend on a bunch of things. Take one panel and times three for later.

The controller has "input watts" at "24v" and "output watts" at "12v"

Say the panel is aimed at the sun at high noon on 21 June so it is 325W. Now reduce that by 10% for panel heating, so you have 292.5w Let's say you have a very good 2% wiring loss from panel to controller, so now at 286w as your "input watts" ( With 37v Vmp, Imp is 7.7a)

(So BTW that means your array to controller wire will carry 3 x 7.7= 23a amps for choosing wire gauge)

Controller efficiency is say 95%, so output watts is 272w

Amps to battery will be 272 divided by battery voltage at the time.

272/12.5 = 21.7a
272/13 = 21a
272/14 = 19.4a
272/14.5 = 18.76a

So your controller to battery wire carries 3 x 22 or more if battery lower, so call it 3 x 25 = 75 amps so #6 AWG needed.

With the panels flat instead of aimed you get less of course. How much less depends on latitude and time of year for how high the sun gets. You might see 10% less, eg depending.

4210 specs for another post! Might be confusion there.