Battery Bank Fuse Size?

BilljustBill · May 2015

As things are coming together for the start of my 4kw solar project, I'd appreciate help along the way.

I have 8, six volt, L16 batteries rated at 440ah each. I have enough 4/0 THHN wire from the batteries to run to two Outback GVFX 3524 inverters for a 220v AC output.

How do you see wiring the battery bank output to both inverters? The battery bank is in one small power vented room with the controllers and inverters 2ft. away in another passive vented room. The small rooms are built under a 10' by 54' long ground array steel tubing framework that is 76 ft. from the House/Solar home wall disconnect.

What type and amp size of fuse/disconnect should I use between the batteries and the 24v inverters? Something like this?
http://www.amazon.com/Holder-Fuseholder-Inline-Battery-Install/dp/B00DNE0HAS/ref=pd_rhf_dp_s_cp_6_7GV7?ie=UTF8&refRID=1TVHBDZ294NPFCSTN740

I'll need to understand how to install the two inverters, and wire them from the battery bank, as well as how to run the outputs (fused/breakers?) for 220 volts to a house fused disconnect. Although the system most likely will never be a grid tie, just a DC battery system, I'm wondering if I need to have the two phases of grid 220v AC out to the inverters to kick in when the battery bank goes below 80%?

Thanks for your help along the way.,
Bill

Vic · May 2015

Hi Bill,

It is customary to have separate cable runs from the battery bank to each inverter.

It is also customary to use Circuit Breakers -- one for each inverter -- to protect these cable runs. Normally these would mount in an OUTBACK conduit box, or perhaps the MidNite e-panels. Many e-panels come with breakers, and you can often buy them, factory-wired:

http://www.solar-electric.com/installation-parts-and-equipment/midnite/misoe/epaforouin.html

You should look at all of the OB documentation in the manuals for those inverters. Generally, the OB docs are very comprehensive.

You MIGHT find that fine-stranded cable would be a lot easier to work with, than THHN building wire.

Opinions, FWIW. Good Luck, Vic

Vic · May 2015

And, this is probably the size and style breaker that the 3524 inverter would like, with individual 4/0 cable runs -- one breaker for each individual cable run:

http://www.solar-electric.com/instal.../mnedc250.html

The OB Docs should have recommendations for cable sizing vs length and breaker sizing.

EDIT: Here is a Link to the OB manual for the GVFX 3524:

http://pdf.wholesalesolar.com/inverter%20pdf%20folder/Outback_fx_vfx_installationManual.pdf?_ga=1.38704231.55768531.1332782786

The wiring diagrams are not quite as comprehensive as I would have liked, but probably will help you get going, if you do not have this Installation manual.

FWIW, Vic

verdigo · May 2015

Midnite E-Panels have some great schematics that come with them and all of the manuals can be downloaded in PDF format for printing.

Battery Bank Fuse Size?

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