Fuse panel question

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NScooknet
NScooknet Solar Expert Posts: 30 ✭
in Solar Beginners Corner #1
Hello,

I've been told that it is a good idea to put a breaker or fuse between the solar panels and the input of the charge controller.

I agree with this as you can never be too safe.

My question is this: What kind of breaker or fuse panel should I buy?

I was at the hardware store today, and was looking at the small 6x8" box that has a 30 amp breaker and a off on lever switch on it, which seemed like a good idea to be able to turn off the power from the solar panels if need be.

What I was wondering is if it was ok to use with DC, as it only had AC usage ratings written on it, and didn't mention DC at all.

Would something like this work with DC??

It actually has the screw in fuse type mini breakers where that little center pin pops out when it trips, not the flip switch type breakers. You could unscrew it and replace with a standard screw in fuse if need be.

I like the idea of being able to turn the solar power input off with a switch, and that if anything were to cause a power surge on the solar panel cables that my controller and everything else would be protected, you may laugh but I'm actually one of those people concerned about a CME (coronal mass ejection) so I'm building a Faraday cage around my system inside the house, and grounding it, and would like to make sure that if one happened, it wouldn't fry my equipment.

What do you think??

Is this the proper box and breaker to install for DC??

Chris :)
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  • vtmaps
    vtmaps Solar Expert Posts: 3,741 ✭✭✭✭
    #2
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    Re: Fuse panel question

    They must be DC breakers. Many DC breakers must be installed in an upright position and many are polarized.

    As I understand it, you should have two breakers in series between the panels and the charge controller. The disconnect breaker is breaking current from the panels to the charge controller so its + side is connected to the panels. The other breaker's function is to break current from the charge controller to the battery and its polarity is opposite the disconnect breaker. You might be wondering why current from the charge controller would be flowing to the panels... it shouldn't... but when things go wrong in the controller you want to protect the wiring to the panels from the full current possible from the battery. This second breaker is often part of a GFP device. The second breaker may also be put in the connection between the charge controller and the battery. Midnite solar has a good selection of the appropriate breakers and NAWS sells them at a good price.
    --vtMaps
    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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  • NScooknet
    NScooknet Solar Expert Posts: 30 ✭
    #3
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    Re: Fuse panel question
    vtmaps wrote: »
    They must be DC breakers. Many DC breakers must be installed in an upright position and many are polarized.

    As I understand it, you should have two breakers in series between the panels and the charge controller. The disconnect breaker is breaking current from the panels to the charge controller so its + side is connected to the panels. The other breaker's function is to break current from the charge controller to the battery and its polarity is opposite the disconnect breaker. You might be wondering why current from the charge controller would be flowing to the panels... it shouldn't... but when things go wrong in the controller you want to protect the wiring to the panels from the full current possible from the battery. This second breaker is often part of a GFP device. The second breaker may also be put in the connection between the charge controller and the battery. Midnite solar has a good selection of the appropriate breakers and NAWS sells them at a good price.
    --vtMaps

    That makes complete sense to me, thanks for taking the time to explain it.

    I know alot of people who kicked themselves for not adding a simple fuse or MOV to their circuit design, and alot of people forget them.

    I'm not only interested in maintaining working equipment, but I kinda don't like that bursting into flames thing and causing a fire either, so safety first in my house...lol.

    I guess alot of people probably figure that since their solar panel has a built in blocking diode that they don't need the fuse, but a fuse is a fuse, and a diode is a diode.

    Thanks again!

    Chris :)
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