What is between your Solar Controller and Batteries? Fuse, Breaker, Disconnect, nothing or what? Med to larger system; 720 watts, MPPT Controller & #4 wire to Controller and three feet of #2 to Batteries. Already have breaker between controller & panels.Thanks,rocmoc n AZ/Mexico

We have a Fuse on the Hot and a Shunt on the Negative.Wires are Welding Cable, I can't remember the sizes of either the Fuse or the cables but they were pretty stout ! Probably 80 Amp and# 2 Cable .

A shunt in the negative, that was all until my controller went south. Then I installed a switch in the positive. I don't have any fuses before or after the controller.

About 2' of #4 and a 70 amp Maxi-Fuse.

The controller installation manual will tell you what you should do. What actually gets done can be different :) Some say if the wires are not into a wall where you can't see if they are melting, it is ok not to fuse them and just let the wire be the fuse, since it won't cause a fire in a wall you can't see. Others say to just do what you are told.Those wires of yours are way overkill for the solar job, so you only need to fuse against battery failure. Not sure what the proper size fuse would be for three feet of #2 at whatever amps. Pick something a little over (1.25 times is often recommended) the max expected amps from controller to battery.I have my solar to battery join in at a buss where closer to the battery there is already a fuse on that pos wire. With a buss you are supposed to have a big fuse to the battery that takes all the amps coming into the buss and then each "branch" (one would be your solar) gets its own fuse before the buss, sized according to the max amps of that branch. The solar would usually have a smaller fuse than the converter's and the inverter's would be quite big. Then you add all those input amps up and fuse the last wire to the battery from the buss for that total. NEC in the States wants 1.25 margin for fuses above expected amps IIRC (check it out if important to you--I am not sure exactly)

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rocmoc

Explorer

Feb 27, 2015

Between Solar Controller & Batteries, What?

What is between your Solar Controller and Batteries? Fuse, Breaker, Disconnect, nothing or what? Med to larger system; 720 watts, MPPT Controller & #4 wire to Controller and three feet of #2 to Batteries. Already have breaker between controller & panels.

Thanks,
rocmoc n AZ/Mexico

RJsfishin
Explorer
Feb 27, 2015
A shunt in the negative, that was all until my controller went south. Then I installed a switch in the positive. I don't have any fuses before or after the controller.
robatthelake
Explorer
Feb 27, 2015
We have a Fuse on the Hot and a Shunt on the Negative.
Wires are Welding Cable, I can't remember the sizes of either the Fuse or the cables but they were pretty stout ! Probably 80 Amp and# 2 Cable .

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Between Solar Controller & Batteries, What?

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