# Fuse for my system

Registered Users Posts: 8 ✭✭
Hi. I had 2 panels 250 watts in parallel. A 60 amp charge controller and 2000 inverter. Also 230 amp battery bank with cable size 10. What kind of fuse I need between panels and charge controller, charge controller and battery and from battery to inverter?

Hterron,

http://forum.solar-electric.com/discussion/353232/oversized-wire-and-breaker

The short answers. As in your other thread, the fuses/breakers protect the wiring... So if you use 60 amp or 80 amp rated wiring, then you need a 60 amp or 80 amp fuse/breaker rated for the working voltage (12 VDC) and interrupting current (a lead acid battery bank can output pretty high short circuit current--Good quality fuses/breakers over ~1,000 AIC (amp interrupt) would be a good startu
Note for off grid power systems, I suggest that your wiring/breakers be sized ~1.25x larger than the maximum rated current you expect. In North America, fuses and breakers are generally rated to open at 100% of rated current (seconds to minutes to hours), and not open at 80% of rated current (1/0.80 = 1.25).

Using this NEC chart for wiring is a good place to start:

https://lugsdirect.com/WireCurrentAmpacitiesNEC-Table-301-16.htm

For your AC inverter, I remember that you plan on using 1,000 Watts maximum of your 2,000 Watt inverter (with very good wiring and 12 volt batteries, you can "reliably" support around 1,200 to 1,800 Watts. A 230 AH @ 12 volt battery bank I would suggest a maximum wattage of ~500 Watts continuous for your lead acid batteries--Basically 250 Watts per 100 AH battery bank capacity @ 12 volts).

The maximum continuous current for a 1,000 Watt 12 volt inverter (load) would be:
• 1,000 Watts * 1/0.85 AC inverter eff * 1/10.5 battery cutoff voltage = 112 Amp maximum current draw @ 1,000 Watts
• 112 amps * 1.25 NEC derating = 140 Amp minimum wiring+breaker recommended
The above is conservative, but you don't want to have to hunt down gremlins in the future.

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset