12v, 24v, 48 volt, or 120 volt?

Most people begin with a 12 volt system because of it's simplicity, and the ability to charge the battery bank with an automobile alternator. However, one must consider that the voltage one obtains from the system is ten time higher. Converting from 12 volts to 120 volts is not efficient.

An ideal system is one in which the DC voltage is equal to the AC voltage. For instance, if you are using a grid-tie system whereby you are feeding your excess power back into the grid, you would want a 220 volt system.

Off-grid systems are most cost effective at 24 volts. Most midsize wind turbines produce either 24 or 48 volts. By having either a 24 volt or 48 volt battery bank, you can easily and inexpensively use the same charge controllers for either wind or solar.

By using a 24 volt system, the equipment is inexpensive and easily obtainable. One can add a wind generator down the road with no modification of the system.

The higher the voltage, the more efficient the system. Higher voltage also allows for longer distance between the solar panels or wind generator and the battery bank and inverter.