The electricity generated by a solar panel always starts as direct current (DC). Standard household electrical outlets must provide alternating current (AC) electricity, which most motors require.

Solar power systems therefore require an inverter to make AC electricity.

According to biophysicist Dr. Bill Bruno, off-grid solar DC lighting systems can be very safe, However, modern inverters, including “pure sine wave” inverters, use electronically switched transformers that operate at several tens of kilhertz, generating harmonics all the way up to at least 100 megahertz. Unless enclosed in metal housing with proper filters on every wire, this radiofrequency radiation will escape through the air and along the wiring.

An inverter’s instructions may advise that if your radio or TV stop working, move them further from the inverter. Thus, many cheaply made inverters generate magnetic fields that Prevention Magazine calls “dirty” electricity. Prevention’s Nov., 2011 report describes how such magnetic fields and “dirty” electricity are health hazards.