Fusing a solar panel system

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Fusing a solar panel system

Postby mustangcats » Thu Jul 06, 2017 7:15 pm

I need to fuse between the 100 watt solar panel and the 30 amp charge controller, and also from the charge controller to the battery. The wires are #10 awg. What type of fuse holders do I need? The in-line fuse holders at the auto parts store had much thinner wires and I need fuse holders that can be wired with the #10 wire.
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Re: Fusing a solar panel system

Postby featherliteCT1 » Thu Jul 06, 2017 7:48 pm

I used this 10 amp inline fuse block from Renogy , close to 10 awg output lead from my 100 watt solar panel … it comes with the fuse. I used Renogy brand because the other look a likes have poor fitting connections ...
https://www.renogy.com/renogy-mc4-water ... er-w-fuse/

I used this 30 amp resettable inline fuse on that same 10 awg input lead into my 30 amp controller...
https://www.amazon.com/INLINE-WATERPROO ... B0199CY96U

I used this 50 amp resettable breaker for my 2 awg wire at my 100 amp battery ... you can also find this at most auto parts stores ...
https://www.walmart.com/ip/Bussmann-CB1 ... 3=&veh=sem
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Re: Fusing a solar panel system

Postby John61CT » Thu Jul 06, 2017 8:21 pm

mustangcats wrote:I need to fuse between the 100 watt solar panel and the 30 amp charge controller
why do you think so?
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Re: Fusing a solar panel system

Postby mustangcats » Fri Jul 07, 2017 7:13 am

John61CT wrote:
mustangcats wrote:I need to fuse between the 100 watt solar panel and the 30 amp charge controller
why do you think so?

That is what the manufacturer recommends. I suppose something could malfunction with the solar panel and fry the charge controller or worse.

featherliteCT1 wrote:I used this 10 amp inline fuse block from Renogy , close to 10 awg output lead from my 100 watt solar panel … it comes with the fuse. I used Renogy brand because the other look a likes have poor fitting connections ...
https://www.renogy.com/renogy-mc4-water ... er-w-fuse/


I saw those on their website and thought they were a little pricey. I may get one afterall since I won't have to cut the wire and the fuse will be out of sight on the roof. I'll get a fuse block to mount on the line next to the battery. I saw those at the auto parts store. Then everything should be safe. :thumbsup:
Last edited by mustangcats on Fri Jul 07, 2017 8:41 pm, edited 1 time in total.
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Re: Fusing a solar panel system

Postby H.A. » Fri Jul 07, 2017 1:53 pm

That is what the manufacturer recommends. I suppose something could malfunction with the solar panel and fry the charge controller or worse.

Manufacturer has to CYA, We cant fault them for it.
On small scale solar, It hurts nothing to include that fuse, But Its really not really needed. A 100 watt module cant produce enough amperage to harm the 10awg conductors to charge controller.
The leads from controller to battery should be fused as manufacturer suggests.

There is tons of automotive electrocrap selling Amazon, Ebay et.al. One should develop understanding to recognise it.
Just for fun, Google images "melted fuseholder".
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Re: Fusing a solar panel system

Postby featherliteCT1 » Fri Jul 07, 2017 6:21 pm

Not long ago, my 100 watt solar panel shorted out and fried my 30 amp controller. I had no fuses between the solar panel and the controller. So, when I bought another $130 controller, I installed a 10 amp fuse at the panel and a 30 amp fuse at the controller.
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Re: Fusing a solar panel system

Postby bdosborn » Sat Jul 08, 2017 8:06 pm

I don't think code requires a fuse until you have 3 or more panels and the fuse is supposed to protect the wire, not the panel or controller. The reality is that a #10 wire will carry the short circuit current of a 100w panel indefinitely since the wire is typically rated at 30A and the panel output is around 6A. However, if you wanted to use a fuse I would size it at 1.56 times the fault current rating of the panel (Isc*1.25*1.25) or at least I think that's what code calls for. That accounts for the increased current and higher irradiance possible in the field compared to standard test conditions so hopefully you won't have any nuisance trips.

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