solar fuses

[Muddydogs]

What fuses are you guys using to connect you solar panels to controller and controller to battery's?

[mena661]

Muddydogs wrote:
Seems like if something happens in the confines of a trailer a fuse isn’t going to help much, the battery or controller will still be pumping juice through the line up to the fuse block most likely melting wire and starting a fire. On my trailer near as I can tell the main lines off the battery to the converter are not fused.

Doesn't work that way. DC requires a circuit. Think of a circle. If you break the circle (circuit), nothing happens. A popped fuse stops current (amps) flow.

[ken_white]

Muddydogs wrote:
So here is a question.
So say I have a 30 amp fuse on the line between my battery and controller and either the battery shorts or the controller does and blows the fuse what good is the blown fuse since there is still a hot line active? Seems like if something happens in the confines of a trailer a fuse isn’t going to help much, the battery or controller will still be pumping juice through the line up to the fuse block most likely melting wire and starting a fire. On my trailer near as I can tell the main lines off the battery to the converter are not fused.

Fuses are designed to protect the wiring and they should be place as close as possible to the energy source.

If they are, then you are protected...

[Muddydogs]

So here is a question.
So say I have a 30 amp fuse on the line between my battery and controller and either the battery shorts or the controller does and blows the fuse what good is the blown fuse since there is still a hot line active? Seems like if something happens in the confines of a trailer a fuse isn’t going to help much, the battery or controller will still be pumping juice through the line up to the fuse block most likely melting wire and starting a fire. On my trailer near as I can tell the main lines off the battery to the converter are not fused.

[RJsfishin]

I have said it a million times,....many heavy cables are not fused or CB from OEM. I would guess they figure, "what are the odds of it shorting"
If thats good enuff for them, its good enuff for me.


Living life on the cutting edge ! 🙂

[Twomed]

pianotuna wrote:
Hi Twomed,

Yes, but how many watts?

Twomed wrote:
40a on the roof, disconnect box with 40a in 30a out after Tristar60

Fuses are cheap... fire is expensive, pretty simple. ??

Sorry for late reply...running MT to FL. 600 watts

[mena661]

TechWriter wrote:

Me. Breakers also serve another purpose -- breakers make it easy to service your system by just flipping a few switches.

Nothing wrong with that.

[TechWriter]

mena661 wrote:

2oldman wrote:
Fuses are not required for series PV installations, as mine is. Go ahead, tear me apart.

NEC only requires fuses when you have 3 or more parallel strings. That's a minimum of 6 panels wired series/parallel. Anyone here have that kind of setup?

Me. Breakers also serve another purpose -- breakers make it easy to service your system by just flipping a few switches.

[Muddydogs]

Thanks guys, know I at least know what I need and to look for.

[KD4UPL]

Fuses, as well as breakers, have both a current rating and a voltage rating. If you're wiring panels in series be sure you don't exceed the voltage rating of the fuse.
However, as has been said, if you have only one or two parallel strings of panels no fuse is necessary. A short won't harm anything. You can short a panel's output together forever and it won't be damaged.
You MUST have a fuse between the battery and charge controller. A short here will cause hundreds of amps of battery current to flow and likely start a fire.

[RJsfishin]

300 watts, no fuses, no switches.

What about the shorts talked about ?
When I install "anything", I make sure it can't short. Well,.....no more chance of it shorting than would the main pos & neg posts coming out of my battrees.

[Almot]

Muddydogs wrote:
What fuses are you guys using to connect you solar panels to controller and controller to battery's?

Don't know if yours is PWm or whether this would make a difference, so I will speak of MPPT.

No fuses panel to controller. Shorted input of MPPT won't trigger a fuse anyway, because Isc of PV is only marginally higher than Imp. It is desirable, however, to have a switch for PV disconnect. So I simply installed a breaker slightly exceeding Isc. It can be used as a switch, and it works as a resettable fuse.

Fuses or breakers after controller don't matter what type, it only matters what current. I have all Pos wires before battery coming to a common Pos bus. There is a "battery fuse" mounted directly on the battery terminal: Blue Sea terminal fuse block. And there are breakers (you may have fuses if you like) in all the Pos wires coming to that common Pos bus: MPPT output, trailer loads, etc etc. This is how it should be done - with a common Pos bus. In a decent controller such things are explained in the manual.

[time2roll]

I use a Blue Sea Maxi fuse holder between controller and battery. 70 amp
My high voltage switch required a couple fuses to complete the circuit. 10 amp

[mena661]

2oldman wrote:
Fuses are not required for series PV installations, as mine is. Go ahead, tear me apart.

NEC only requires fuses when you have 3 or more parallel strings. That's a minimum of 6 panels wired series/parallel. Anyone here have that kind of setup? When I get my solar setup, there will be no fuses on the panels to controller side. A hint on why: solar panels are designed to be shorted. You're not protecting those, you are protecting the wire and only when you have X number of panels connected will you ever stand a chance of going over a wires current limit.

[Bend]

+1 on the MNEPV breakers on +, combo box - controller, controller - battery.

[westend]

Panel to controller: CB Midrange 25 amp manual reset

Controller to (+) phase busses: 40 amp Midi fuse