AC and DC Loads
AC (alternating current) electricity is the type provided by the local electric company, and is the type most people are familiar with. AC electricity is what operates common household appliances and shop tools. To power AC loads in an alternative energy system, you will need either an engine generator (which produces AC power) or an inverter (which changes DC power to AC). You can also use an AC power source (like a generator) to power DC loads, if you have an AC to DC "convertor."
DC (direct current) electricity is the type stored by batteries and is what powers your automobile electrical system (lights, radio, etc.). DC electrical appliances (lighting, refrigerators, etc.) are easily available from stores, and often provide better efficiency than their AC counterparts. Most renewable energy systems utilize both AC and DC electricity.
In most cases, both the electrical system (wiring, switches, etc.) and the loads it provides power to are rated for either AC or DC current. It is important to keep AC and DC electrical loads and systems separate. Serious damage to the electrical system and any loads connected to it can occur if the AC or DC loads or wiring are connected to the wrong type of current, introducing a high risk of fire and/or personal injury.