So far, the discussion of solar electric systems has focused on converting the DC power they produce into the AC power used in our homes. I’d be remiss to leave the discussion there. Solar electric systems can be designed to use DC power directly for all circuits or a few. In my home, for instance, I run a small DC electric pump to pump water from my cistern to the house. This pump uses 24-volt DC current.

I did this for one simple reason: to bypass the inverter both to save energy and to simplify the system. How does bypassing the inverter save energy?

Inverters consume energy when they’re operating. For example, when my inverter converts 24-volt DC electricity from my batteries to 120-volt AC current, it loses about 10 percent of the energy that goes through it. By bypassing the inverter with a DC circuit to the water pump, I raise the efficiency of my system.

Other appliances and consumer electronics can also be run on DC power. For example, SunFrost refrigerators, which are one of the most efficient refrigerators on the market today, can be ordered with DC components at no extra cost. Because refrigerators account for about one tenth of your daily electrical consumption, you can save substantially by purchasing a DC refrigerator and bypassing the inverter.

Ceiling fans can also be ordered in DC models. Here, though, you need to think carefully. I was planning on doing this until I found out that DC ceiling fans cost $200 each, compared to $40 each for standard AC ceiling fans. I couldn’t justify spending $480 more for three ceiling fans to bypass the inverter.

Many other DC appliances are available, but they tend to cost more and are typically designed for use in RVs or cabins. They’re not ideal for household use, unless you’ve pared down your demands.

As a rule, then, DC circuits aren’t of much value in most homes. But don’t close the book on them. Johnny Weiss recommends installation of at least one DC circuit to power a light bulb in the utility room (where the inverter is located) in case of emergency.

Learn more about Powering Your Home with Solar Electricity .