System Voltage Selection: 12 or 24 volt?
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. 24 or 48 volt
systems are suggested for medium to large systems. With 24 /48 volts we
have less wire loss problems and larger inverters are available. 24/48
volt DC appliances are more rare than 12 volt units. For this reason we
lean heavily toward AC loads for these larger systems. This simplifies
wiring of the home to conventional AC wiring which exists in most homes
and which any electrician can wire economically.