I’m interested in building a power wall for home use. Typically you see lithium-ion batteries up to 14s for use in ebikes and all kinds of low-voltage DC applications. For home use you want 220V AC (or 110V AC for Americans).
An inverter would waste a lot of energy going from 12V to 220V at high wattages. The lower the voltage, the more amps are drawn and thus more energy becomes waste heat. You also need thick wires to not have them become fire hazards. The battery also gets strained when drawing high amps from them.
Would it be sensible to build a 60S battery? Transformation losses from 240VDC-> 220VAC should be quite minimal. You can put enough solar panels in series to make charging this battery sensible as well.
Of course there are obvious safety hazards with high voltages but there should be advantages as well, lower strain on battery cells and minimal DC->AC losses.
You are right on the efficiency but as others have said working with DC voltages that high is dangerous. That many batteries in series would also be hell to monitor so you are one bad cell away from burning down your house. Generally when working with DC you want to keep it under 50V to avoid electric shock risk.
For powering a home multiple 48V arrays in parallel is the best bet. You can easily find inverters for that voltage and just bumping the voltage up to 48V avoids a ton of losses without risking electeocution or making the system overly complex. 60V and 72V inverters are also readily available but that’s just risking electrocution for minimal additional benefit. You would also want to be using lithium iron phosphate batteries (LiFePo4) instead of regular lithium-ion batteries. They aren’t quite as energy dense as most lithium-ion chemistries but they are much more safe, much less picky about charging characteristics, and much more long lived. You can get them in 12V cells just like lead acid batteries because they are frequently used to replace lead acid batteries in stationary power storage applications. Depending on the cells you get they can be a pretty much a better drop in replacement for lead acid batteries however it is normally still a good idea to get chargers and inverters designed for them to get the most out of them. That’s because they store much more power than lead acid batteries and unlike lead acid batteries they can be charged just as quickly as they can be discharged.
Source: I did portable inverter setups for a few years.