When I was first considering going off grid, I researched and discovered that for every 1 amp of AC (120v), I would need 10 amp of DC (12v). So, in a spark of, no doubt, ignorance and misunderstanding, I figured I'd run 120vDC, and save myself some complication.
Research which led me here taught me that true sine wave vAC at "120v" actually peaks closer to 170v. No problem, just add 4 (168v) or 5 (180v) 12vDC cells, and we'll be all set. And, gosh, wouldn't you know it, batteries can even come in 2 volt, single cell sizes (rather than 6 cell sizes). Who knew? Even easier to nail down that exact 170v I'm aiming at! Further research taught me that modern inverters 2 step the conversion of DC to AC by first "inverting" the voltage from 12vDC to 160vAC @ 25KHz, then back to 160vDC, then finally to 120vAC @ 60Hz (for the states) true sine (rms?). Somehow this triple conversion allows an inverter to be ~1/10th it's normal size (3 lb/kw rather than 30 lb/kw... at least, that's the aproximation and it's reportedly due to "physics").
It appears that, at least electrically, there is no inefficiency from having to step voltage up or down from the DC power source, so planning for a 168-180vDC system is pointless--unless I have an application which requires massive amperage via shallow battery draws (which I don't, it's just a regular old house), though I suspect my batteries would love the pampering. 
Otherwise, wouldn't there be some mention of it somewhere?
Regardless, I'd like to understand why, even if only briefly explained. It seems that pushing ~170vDC into an inverter would allow for simpler construction (hence cheaper?) at the very least.
