breaker or fuse?

[ImpatientMaker]

I'm laying out the components of my portable solar generator. Currently I have a 200A fuse to go between battery and inverter. However, I'm considering buying a breaker instead, mostly so I have a convenient "off" switch.

Also wondering how to figure out what size. I upgraded from a 2000w to a 3000w inverter so I'm thinking I need a larger breaker/fuse.

 

[gnubie]

The current can be derived by dividing the watt rating by the DC voltage coming into the inverter. Since you are running from battery the voltage will go down as the battery discharges and also as load on the battery increases. Let's assume you have a 12 volt lead acid battery and have set a low voltage cut off at 11 volts. The calculation would be 3000 / 11, giving about 273 amps. Add in allowances for brief surges, for inverter startup; starting high power AC devices etc; and losses in the inverter itself, and the fuse should be IMO rated for somewhere around 350 amps.

Be careful when buying high current DC breakers. There's a lot of junk out there. Can you post a link to the breaker you are considering buying?

 

[ImpatientMaker]

The current can be derived by dividing the watt rating by the DC voltage coming into the inverter. Since you are running from battery the voltage will go down as the battery discharges and also as load on the battery increases. Let's assume you have a 12 volt lead acid battery and have set a low voltage cut off at 11 volts. The calculation would be 3000 / 11, giving about 273 amps. Add in allowances for brief surges, for inverter startup; starting high power AC devices etc; and losses in the inverter itself, and the fuse should be IMO rated for somewhere around 350 amps.

Be careful when buying high current DC breakers. There's a lot of junk out there. Can you post a link to the breaker you are considering buying?

Thanks Gnubie! Really helpful. I'll use my 200A fuse for now and order a higher amperage one. TBH, reviews on cheaper breakers on Amazon confirm your assertion about junk - The exception seems to be Blue Sea products. I think I'll go with fuse and just a switch, like this one.