It's not hooey. I've got 2 circuits - one for 240VAC, and another for 24VDC. The cabling is identical, i.e. normal 240VAC live + neutral + earth, 10-amp. The low voltage circuit uses the same cable, but doesn't use the earth wire, and the individual circuits were designed to make sure no more than 10 amps were possible on any outlet. The low voltage system is used for lighting (although 24 volt light bulbs are rare and expensive), and a couple of 24 volt power outlets, one of which is used for refrigeration - a normal fridge converted to use a Danfoss 24 volt compressor.
There are more drop-in DC LED lights these days, and they can take 8-30 volt input, so I'm gradually replacing the halogens with LEDs.
There's a good reason to use 240VAC cabling on a 24VDC circuit - even though you have to install 3-4 x runs, 240 cabling is cheap, and 24 volt cabling is not cheap.
Conversion losses are an issue - the inverter runs about 85 - 95% (better at higher loads), and the batteries (lead-acid) are also about 90% efficient, i.e. you need to put about 10% more back in than you take out - so you just up the PV numbers to account for that.