The capacity of the battery bank is dependant on what is going to be used on the system, whether a household, telemetry system, cctv system or whatever.   Enough power has to be available in the battery bank to support the end user.   Care has to be taken on the type of batteries used, all of our systems use "Deep Cycle" Batteries, these are made for this type of application.   We do come across sites where other types of batteries have been used, such as fork lift truck batteries, even leisure batteries.  Although some people have lived off these successfully in the past, it is not recommended to use them for off grid living, that is where the "Deep Cycle" batteries come into their own.

Charging of the batteries correctly is paramount to the longevity of any system, again, get this wrong and you can have problems with short battery life.

The battery bank is probably one of the most expensive parts of any system, these can cost over half of the entire system.