In other words is it possible to have a large 12v system operate with similar efficiency like a large 24v or 48v system?
I would say a large 12V system would be 2,000 watts. A large 24V system would be 4,000. A large 48V system would be 6,000 or more.
In theory you can achieve close to the same electrical efficiency with 12V, just that it takes more equipment. An example; say you have two 12V batteries on a 12V system operating at 1,200 watts. The batteries will obviously be in parallel, total amp draw on the system will be about 100 amps with no inverter losses, each battery must deliver 50 amps. Use those same two batteries in series on a 24V system @ 1,200 watts and the amp draw of the system is now 50 amps. However, each battery is still delivering the same 50 amps to the inverter that they do on 12V.
So hopefully you can see from the example above that building a large 12V system requires using more parallel components, including charge controllers, wiring, and inverters. And it is easily doable - most RV's are 12V and some of those rival many off-grid homes. I like 12V systems for off-grid cabins and smaller off-grid homes because the parts for it can be economically sourced from the thousands of RV dealers and automotive parts warehouses scattered across the country - especially lighting. Once you go to 24 or 48V you need less equipment, but it's unproportionately more expensive equipment. Even something as simple as a circuit breaker or relay for 24V is not commonly available and costs 4x what one will cost for 12V from the automotive or R/V industry.