Big ass -48vdc battery banks, float charge controllers and precision sine wave inverters are a solved problem. If it's good enough for a $235,000 Infinera DWDM platform...
Floor space is severely limited in Japanese homes however. I'm not an expert but what you describe sounds large. Most have a little bit of space at least on one side of the house however due to Japanese building code, so your own pole might actually be more practical ;-).
The funny thing is, all audio circuits run on DC power, thus necessitating the inclusion of an AC/DC converter in every piece of hifi equipment on the planet.
So if you go to the trouble of setting up a battery bank, it would make sense (both financial and sound quality) to ditch the sine wave inverter and hack your equipment to accept DC directly.
You know what's interesting to me? Almost everything runs on DC these days. Lights are solid state, just about all electronics have a power supply that converts to DC, even a lot of (admittedly high end) home gadgets use brushless DC motors. The only AC devices I can count in a normal home are the big appliances like electric stoves, HVAC fans, etc. I wonder why there has not been more progress in a DC home distribution standard. Especially because efficiency generally increases with load, all of those little wall warts are less efficient than one big AC to DC converter.
because there's no single DC voltage that all devices use, so you'd end up with homes wired with 48VDC and many power brick/wall-wart dc-dc converters to obtain 24VDC, 19VDC, 17.5VDC, 12VDC, 5VDC, etc.
and the cable gauge would need to be incredibly thick to avoid significant losses, DC does not go very far distances well at all. Be ready to pay for #2 gauge copper in your walls instead of 14ga.
