A roughly 21-acre field near Houston was transformed this year into a 3.9 megawatt solar farm that will help power more than 400 local homes and businesses through the Tennessee Valley Authority.

Solar panels may look sci-fi futuristic, but they operate simply.

A solar cell — also known as a photovoltaic cell — is made of a semiconductor material such as silicon. When sunlight strikes the solar cell, the semiconductor material releases electrons, which are captured by electrical conductors. Electricity flows when the conductors are connected to an external device, such as an appliance or battery.

Solar cells are usually connected in groups of thin, wire-like circuits that run between a tempered piece of glass and a pane of mirror-image glass as backing. These are the basic parts of a solar module or panel.

Circuits in a panel collect solar energy, generating direct current, or DC, electricity. This energy flows through wires to devices called inverters to convert that power to alternating current or AC electricity that can be put to immediate use by a power company or in one’s home.

Sources: U.S. Energy Information Administration; National Aeronautics and Space Administration; Paul Hankins, a worker for STI Solar