Xantrex XW 6048 DC breaker sizing

offgrid12

I was looking at the XW 6048 inverter and trying to decide how to size a breaker for it. I am guessing I would either need a 175 A or a 250 A breaker. The manual says 130 A at rated power and the sticker on the inverter says 160 A maximum. So if I take 1.25% * 130 A = 162.5 A, I get a 175 A breaker and if I take 1.25% * 160 A = 200 A, I get a 250 A breaker. Is there anyone that has this inverter that knows how to size the DC breaker?

BB.

More or less, the starting point is how large of continuous load you want to pull... Basically:

• 6,000 Watts * 1/0.85 inverter eff * 1/42 volt batt cutoff * 1.25 NEC derating for wire/breaker = 210 Amps (worst case voltage drop/low battery charge)

130 amps sounds a bit on the low side... Using the XW ~93% efficiency number:

• 6,000 watts * 1/0.93 XW eff * 1/130 amps = 49.6 volts

Which really does not seem to be a "worst case" number... Even using some less worst case numbers:

• 6,000w * 1/0.93 eff * 1/46 volts batt cutoff = 140 amps
• 140 amps * 1.25 = 175 Amp branch wiring/breaker
• 6,000 s * 1/0.93 eff * 1/160 amps max = 40 volts minimum

So, from my point of view, the minimum breaker I would suggest is 175 amps.

The 160 amp maximum--Not sure if they mean 160 amp maximum input current or 160 amp maximum input circuit breaker (if one existed).

The installation manual is a bit more exact on the wiring requirements:

http://static.schneider-electric.us/docs/Electrical%20Distribution/Solar-Energy/Conext%20XW%20Installation%20Guide.pdf

4/0 cable and 250 amp breaker (page 43/2-12).

-Bill

Ethan Brush

If you really want to be meticulous, sometimes its a bit tricky to figure out what the absolute max input current of inverter is. As Bill pointed out, the input current will vary with voltage, efficiency, etc. In addition, most inverters can exceed their rating for short periods of time. Sometimes a manufacturer will give you an "absolute max" current rating, not sure if thats what that 160A figure was. Note you typically dont need the 125% for inverter input sizing as that is for continuous loads which are 3 hours or more. Technically its "100% of non continuous loads plus 125% of continuous loads". Most of us off griders wont be pulling 6000 watts for 3 hours but use your own judgment and circumstances here. I would be fine with a 175A and 2/0 cables, and that will get keep you under 1.5% voltage drop at 30 feet.

mike95490

My Midnight ePanel for my XW-6048, has a 250A breaker. cable lugs bolt onto it. But the midnight breakers are special fast trip ones (I think) and 12Kw is within the short surge of the unit.