Fusing solar

[Rail_Dawg]

If the controller is 30amp do you fuse the line for 30amps.

[MEXICOWANDERER]

It's when the controller throws a hissy-fit and holds it's breath until it passes out that a fuse comes into play. This is far less common than a fault between the battery and the controller.

Visit the area in an OEM plant. It's sounds like WW 3 staple gun warfare. Now imagine a big panel staple ALMOST shorting a hot wire. It works until it's bounded down the highway a few thousand miles.

Myself I am old fashioned. I put the panels to sleep before working on the system. A tarp or towels.

[Rail_Dawg]

2oldman wrote:

time2roll wrote:
As long as the ampacity of the wire from the panels to the controller exceeds the Isc rating of the panels... no fuse is needed.

x2. I don't really see a need to fuse any of it. So I don't.

Hmm good point.

[Housted]

I fuse both into and out of controller as a convenient way to disconnect for service.
JMHO

Housted

[2oldman]

time2roll wrote:
As long as the ampacity of the wire from the panels to the controller exceeds the Isc rating of the panels... no fuse is needed.

x2. I don't really see a need to fuse any of it. So I don't.

[time2roll]

Rail Dawg wrote:
I’ll fuse at 30 amps between the solar and controller.

There’s also a 30-amp fuse at the battery installed by the manufacturer.

Do appreciate the input!

As long as the ampacity of the wire from the panels to the controller exceeds the Isc rating of the panels... no fuse is needed. You can short the wires all day long with no harm to the wire or panels. A DC rated switch might prove useful to cut power to the controller for service. Most controllers need the solar power disconnected before disconnecting from the battery. Or you can remove that fuse.

[Rail_Dawg]

I’ll fuse at 30 amps between the solar and controller.

There’s also a 30-amp fuse at the battery installed by the manufacturer.

Do appreciate the input!

[scrubjaysnest]

time2roll wrote:
Morningstar says to comply with NEC the fuse (battery to controller) s/b rated at least 20% over the controller rating and wire should have ampacity to match the fuse. So you are looking at 40 amp fuse and #8 wire minimum afaik. Fuse s/b close to the battery not the controller. If you are pushing near 30 amps I would have #6 wire minimum assuming wire fits the controller lugs.

The problem with the NEC on this is the rules apply to grid tie systems which RV's are not. I chose a breaker at the batteries to protect the wire and then another breaker at the CC to protect the electronics.
Just a different approach.

[brulaz]

Fuse to protect the wire first, then reduce that fuse rating to protect the electronics second.

So if your wire can handle 40A but your electronics only 30A, go with a 30A fuse.

[morphrider]

Clicky

[morphrider]

Read Renogy site about fusing. Match the controller, seems if you went a size larger than controller then you risk ruining the controller. Makes no sense to go that 20% higher that windynation refers to. I think that 20% reference goes from the solar panels to the controller, not from controller to battery. Read the clicky below...

[Rail_Dawg]

Thanks guys.

Running #6 will fuse at 40 amps next to battery.

[Lwiddis]

What brand controller do you have? Post all the facts, not just your question.

[time2roll]

Morningstar says to comply with NEC the fuse (battery to controller) s/b rated at least 20% over the controller rating and wire should have ampacity to match the fuse. So you are looking at 40 amp fuse and #8 wire minimum afaik. Fuse s/b close to the battery not the controller. If you are pushing near 30 amps I would have #6 wire minimum assuming wire fits the controller lugs.

[pianotuna]

Fuses are to protect the wire between items. Fuse to the wire size. i.e. #10 30 amp, #12 20 amp, etc.

Rail Dawg wrote:
If the controller is 30amp do you fuse the line for 30amps.