12 24 48 volt

For smaller systems, 12 volts is usually OK. 24 Volts is pretty common and many of the 12 volt switches/breakers/fuses will work at 24 volts too.

48 volt fuses/breakers/AC battery chargers, etc. are more difficult to find.

There are some other issues (if a 12 volt battery cell fails, you know right away--nothing runs at 10 volts--If a 48 volt cell fails, the system can still work at 46 volts--But the bad cell can cause problems in the bank--over heat and cause a fire, discharge other parallel strings, etc.). Also 48 volt battery banks have lots of cells to check (24 cells for a single string, 72 (thank your vtmap) cells for 3 parallel strings).

Usually, you define your loads and power needs and then fit the battery configuration to support those needs. And, a good dividing line--If the battery bank is >~800 AH, look at going to the next higher voltage.

Another, if your loads are around 1,200 to 2,000 Watts maximum, a 12 volt bank is usually fine. If your loads are 1,200 to 2,400 to 4,000 Watts, a 24 volt battery bank is usually a better choice. If your loads are 4,800 or larger, you should be working with a 48 volt battery banks.

That is what's "standard" for off grid solar power today. There are other AC inverters (used in computer rooms and such) that have higher working voltages--But I would suggest that you avoid those unless you have really need them. It is difficult to find solar/AC battery chargers that work at high voltages, and working with large AH / High voltage DC Battery banks is really scary to me. Plus, the number of cells really is asking for a battery management system to monitor for bad cells/problems in wiring/charging--Another expense and complexity (and more things to maintain/go wrong).

-Bill