How do I choose which MPPT Controller I need?

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cadams asked Apr 30, '20

How do I choose which MPPT Controller I need?

Having difficulty figuring out what controller I will need for my solar power boat project. I’m hoping you can help me.

Here is my set up:

(4) 12v deep cell gel batteries 100ah (series)

(2) 100w solar panels with these specifications.

Renogy 100 Watt 12 Volt Mono Solar Panel(Compact Design)
Solar Cells: 33 Cells	Cable: 14AWG (2ft long)
Junction box: IP65	Connector:s MC4 connectors
Maximum Power: 100W	Maximum System Voltage: 600V DC (UL)
Optimum Operating Voltage (Vmp): 17.9V	Open-Circuit Voltage (Voc): 21.6V
Optimum Operating Current (Imp): 5.72A	Short-Circuit Current (Isc): 6.24A
Cell Efficiency: 21%	Max Series Fuse Rating: 15A
Weight: 16.5lbs	Dimensions: 42.2 X 19.6 X 1.38 In

charge controller compatibility

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Answer 1 · 2020-04-30T14:52:14Z

Matthias Lange - DE answered · Apr 30, 2020 at 02:52 PM

https://www.victronenergy.com/mppt-calculator

A 75/10 should be good.

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Answer 2 · 2020-04-30T16:12:35Z

cadams answered · Apr 30, 2020 at 04:12 PM

I was informed by the tech staff to go with the 100/20 48v model.

Since I have (4) 12v batteries hooked up in a series.

Can anyone tell me as far as install, do I need to hook the positive up to battery#1 and negative up to #4?

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Matthias Lange - DE ♦ commented · Apr 30, 2020 at 05:35 PM

oh, you are right didn't saw that. So you need the 100/20_48V.
And yes, you have to use the positive of the first and the negative of the last battery.

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Answer 3 · 2020-05-01T05:16:30Z

JohnC answered · May 01, 2020 at 05:16 AM

Hi @CAdams

The issue you face now is the panels. Those you cite, you'll need 4x of, series-wired to give you enough V to charge 48V batts. There's not much wiggle room with the 100/20_48, so consider carefully what you choose.

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