Trying to understand how different DC setups affect the AC output

[eriemountain]

Can anyone explain (in non technical terms) how different configurations of DC power affect the AC power that the inverter gives? Particularly the difference between high volt/low amp and low volt/high amp setups, assuming the same total wattage. If the combined watts are the same, and it is being converted to 120v AC power, what is the difference, either for the end user or for battery consumption/wear? (ignoring the difference in cost/materials to set up)

 

[DThames]

Power in watts is volts times amps. It takes 4 times the amps from a 12v battery as from a 48v battery to have the same watts. Example,
12v * 40amps = 480 watts
48v * 10amps = 480 watts (on DC side)
Inverter output, will be the same, 480 watts * inverter efficiency.

 

[John Frum]

At 12 volts a 3000 watt inverter requires 4/0 awg(107 mm2) wire and a 400 amp fuse
4/0 awg wire is largest wire that we typically use for diy solar.

That means its impractical to go to a higher wattage inverter at 12 volts.

At 24 volts a 3000 watt inverter requires 2 awg(35 mm2) wire and a 200 amp fuse

At 48 volts a 3000 watt inverter requires 6 awg(16 mm2) wire and a 100 amp fuse.

As the system voltage doubles the ampacity halves.

Also as voltage increases voltage drop as a percentage decreases.
And since voltage drop also increases with amperage the 48 volt system is dramatically more efficient for the same inverter size than a 12 volt system.

 

[John Frum]

It also means it is possible to run a 12000 watt inverter at 48 volts for the same size wire as a 3000 watt inverter at 12 volts.