Inverters: Using Your Power

Batteries deliver direct current, or DC, when you ask them for power. As long as the voltage of your battery and load match, you can tap this energy to run any DC lights or appliances directly. Normal household appliances won’t run on DC though, and DC appliances are usually more expensive, smaller in capacity and harder to find.

Only DC power can be stored, so all your storage happens on the DC side of your system in the batteries. AC power has to be generated on demand. To meet this highly variable demand you need a device called an inverter. The inverter converts low-voltage DC from the battery into high-voltage AC as fast as your household lights and appliances demand it. The appropriate inverter depends on the type of loads you need to run, and how many you need to run at the same time. You want one that will deliver enough wattage to start and run all the AC appliances you might turn on at the same time, but no bigger than necessary.

A second consideration is the quality of the power that comes from the inverter. Usually inexpensive inverters produce a hybrid waveform called a modified sine wave. Most appliances will accept it and hardly know the difference. There are some notable exceptions to this rosy picture, however; ceiling fans, audio equipment, portable power tool chargers and other equipment can underperform or be damaged. Computing equipment generally is okay, though power dips from other loads can cause unexpected crashes.

Pure sine wave inverters have been available since the mid-1990s. A variety of high-efficiency, moderate-cost pure sine wave inverters are available now. Pure sine wave inverters deliver top-quality AC power and are almost always a better choice for household use. Many of the larger, household-size inverters come with built-in battery chargers that come on automatically anytime outside AC power becomes available from starting a generator or plugging into an electric vehicle.