System Voltage Selection - 12, 24 or 48 volts?

The nominal voltage of your system is usually determined by the system size. Small to medium systems, where most loads are DC, or a few loads are AC through an inverter, lend themselves to 12 volts nicely. Many lights and small appliances can be found at this voltage and efficiencies are high.

On the down side, 12 volt suffers from high line loss problems. The solar modules and loads cannot be far from the battery bank. To review the wire loss tables, click here.

24 volt systems are suggested for medium to large systems. With 24 volts we have less wire loss problems and larger inverters are available. 24 volt DC appliances are more rare than 12 volt units. For this reason we lean heavily toward AC loads from these larger inverters. This simplifies wiring of the home to conventional AC wiring which exists in most homes and which any electrician can wire economically.

With the increased efficiency of AC lighting and the unlimited variety of low cost AC appliances, 24 volt systems, as well as 48 for large systems, have many advantages. Most of the modern grid intertie systems are running 48 volts DC or higher.