At about 500 Watts, the poor performance and expense of 12 volt systems outweigh the convenience. The very maximum at is about 1500W at 12V. The problem is that we need to use very big, expensive wire to move more than 500 Watts at 12 Volts, especially over a long distance. The easiest,cheapest, and most effective way to remedy this is by raising the system voltage. Voltage acts like water pressure, the more the better. It is much easier to push a large flow of water (AMPS) through large pipes (Wire) with HIGH PRESSURE (High Volts). High voltage is good and it becomes necessary at about 1000 Watts.
Possibly the greatest advantage is the cost savings. Raising the voltage means we can use a much smaller, less expensive charge controllers while increasing performance at the same time. When we move to 24 Volts, we double our charge controller capacity (cutting our controller costs in half). When we go to 48 Volts we quadruple our capacity (CUTTING CONTROLLER COST BY 75%!). A thoughtfully executed system can save you thousands.
Since having 12 volts available is a very nice thing, we use a simple and inexpensive converter so we can utilize 12 volt accessories.
Batteries and equipment are standardized to increments of 6 or 12 volts, so 6V, 12V, 24V, 36V and 48V. We need to keep this in mind when we size the battery bank. For example, if we wanted to use a 48 Volt system we would need 8- 6V or 4- 12V batteries.