Fuse types - solar power system

[Seraphim]

Asked Renolgy about fuse types. Recommended ANL, and in a separate email stated I'd need a 25a and a 32a fuse (guess I'll use a 30 amp). Can't find ANL fuses that low.

What type fuses are most of you using for your solar array/battery fusing?

---

Or an automotive inline circuit breaker?

 

[Spaceman Spiff]

Asked Renolgy about fuse types. Recommended ANL, and in a separate email stated I'd need a 25a and a 32a fuse (guess I'll use a 30 amp). Can't find ANL fuses that low.

http://www.amazon.com/ANL-Fuse-Audi...id=1416498225&sr=8-2&keywords=30+amp+anl+fuse

I'm using a 60 amp ANL fuse before charge controller (spec'd by Morningstar), off 4 AWG positive wire from solar panels ( 2 x 100 W Renogy panels) and a 60 amp ANL fuse coming off battery positive terminal.

-- Spiff

 

[Seraphim]

I generally overbuild things, but in this case Im starting with the kit, not worrying about efficiencies, since my needs are so minimal. Using 10 AWG wire (10' from array to charger and 2' from charger to battery) I need smaller amperage fuses.

Thanks for the link.

---

Wonder if using two 30amp fuses would be suitable?

 

[wagoneer]

I use no fuses

 

[concretebox]

Wow. 60amps? I put a 7amp glass tube fuse in mine. Maybe my set up is very different than yours. I have a single 100W panel. I have two fuses. One in the positive line from the panel and one in the positive line between the controller and the battery. I couldn't find a pre-wired fuse holder in that range so I used these. One wire is 8AWG, the other is 12 I think.

 

[Spaceman Spiff]

Wow. 60amps? I put a 7amp glass tube fuse in mine. Maybe my set up is very different than yours. I have a single 100W panel. I have two fuses. One in the positive line from the panel and one in the positive line between the controller and the battery. I couldn't find a pre-wired fuse holder in that range so I used these. One wire is 8AWG, the other is 12 I think.

Your setup probably isn't much different than mine. I have 2 x 100 Watt Renogy panels, with 10 AWG going into a roof combiner box, 4 AWG from roof to 60 amp ANL fuse to TS-45 Charge controller. 4 AWG from charge controller to 60 amp ANL fuse. 1/0 from fuse to Battery positive. 4 AWG from battery negative to 500Ω shunt, 4 AWG from shunt to roof box. I used fuse holders similar to what you used, for ANL fuses similar to this:
http://www.amazon.com/Scoshe-EWFH-S...id=1416516334&sr=8-1&keywords=anl+fuse+holder
You should have a fuse between the battery positive and all circuits coming from the battery (in and out). ABYC standard says within 7" of battery. ANL, Type T or MRBF fuses are best.

Here is a chart of wire size and maximum fuse size
http://www.bdfuses.com/fusesnwires.php

MaineSail did a study on voltage drop across fuses. His conclusion: Smaller fuses have larger voltage drop, so use the biggest fuse your wiring will tolerate.
http://www.pbase.com/mainecruising/fuse_voltage_drop

Hope this helps -- Spiff

 

[christine]

I used mini-ANL between:
- the combiner box and the charge controller
- the charge controller and the batteries
- the batteries and the 600 watt inverter
- the batteries and the 12 volt fuse block

I used a Class T fuse between the batteries and the 2000 watt inverter, per the instructions that came with the inverter. That was expensive, but I'm glad I did it for peace of mind.

The XScorpion mini-ANL fuse holders are pretty good. Ebay has low prices on mini-ANL fuses and fuse holders. For the Class T fuse holder and the fuse, I went with Blue Sea.

I'm a fuse-aholic compared to most other solar DIYers.

 

[concretebox]

Spiff,

I'm confused.

In the manual that came with my panels, on page 12 it says: Controller to Battery Fuse = (Number of Panels in Parallel) × (Short Circuit Current of Panel) × 1.25.

I have one panel, the short circuit current is 5.75 according to this. So that's 1 x 5.75 x 1.25 = 7.1875.

It says to use the same formula to calculate the fuse between the panel and the controller. Is there a reason I shouldn't be using this formula?

Unrelated, but I also have a 60amp circuit breaker between the battery and the load output.

 

[christine]

I'd always go with the instructions first. If the fuse blows, check the wiring, make sure everything's wired correctly with the right gauge wire. If everything checks out, replace it with the next higher up size fuse.

By the way, I have the Renogy panels too, and I fused each panel with a 10 amp mini fuse before the combiner box. So far, no fires, no blown fuses. I got the mini fuses at delcity.net

 

[Spaceman Spiff]

Concretebox,

I'm confused as to why Renology would specify a fuse based on solar panels amps? But Christine gave you good advice: 'Go with the instructions'. Your manual must have come with the charge controller, all I got with the panels was a data sheet that didn't specify fusing. My charge controller manual specified a 60 amp fuse.

I got into solar with only basic knowledge of DC (I'm a mechanical engineer), so I am also kind of feeling my way. If your system is working, I wouldn't change it. I would change over at some point to ATC, ATM or Max fuses (newer style automotive fuses; there are good reasons the auto industry changed from glass fuses to spade type fuses).

Christine: Ouch! I had wanted to go with Class T fuses, but those puppies are expensive.

-- Spiff

 

[Seraphim]

Wow. 60amps? I put a 7amp glass tube fuse in mine. Maybe my set up is very different than yours. I have a single 100W panel. I have two fuses. One in the positive line from the panel and one in the positive line between the controller and the battery. I couldn't find a pre-wired fuse holder in that range so I used these. One wire is 8AWG, the other is 12 I think.

Your single panel isn't going to produce more than 7 amps. If it does, there's a problem. Mine will deliver about 20. If it spikes over 25, there's a problem. Hence the fuse differences. As it was explained to me.

It's not what the wiring will tolerate, but what the panel's should be putting out. Too many amps coming across and something's wrong. But no expert here.

---

So I have 4 panels a 32 amp fuse is necessary (4 panels x 6 amps is 24) between the panel's and charge controller, and the charge controller should only be putting about 20 amps to the battery, so a 25 amp fuse between the controller and battery. If I up the amps significantly the cable needs to be larger gauge, else it becomes the fuse and could burn out.

Sound right?

---

You're rusing for the devices, not the wire...

---

Fusing not rusing lol

---

Anyway, the kit is suppose to arrive tomorrow. I can rig up the controller tomorrow, but the panels will have to wait until Saturday, when the temp jumps up to 46F. The ice should have melted by then. Depends on if I can dig up the well nuts I need tomorrow...

---

... And the fuses lol.

---

I'll take photos and notes