What are photovoltaics?

Solar photovoltaics (PV) are devices that turn sunlight into electricity. (The word photovoltaic comes from two Greek words: “photo” means light, and “voltaic” means electricity). Photovoltaics are used in a variety of places– not only solar panels on homes, but also on solar-powered backpacks that can charge electronics, electric car charging stations, and on standalone devices like parking meters. One of the first uses of photovoltaics was to power satellites, starting in the 1960s. Scientists first discovered the “photovoltaic effect” of certain materials in the 1800s, and several decades later (in the 1950s) created solar cells that were efficient enough to power electronics.

The photovoltaic effect

We won’t go into complex technical detail, but here are the very basics of how the photovoltaic effect works. Materials like silicon and gallium arsenide are natural semiconductors. When sunlight hits a photovoltaic cell made from silicon, the sunlight knocks loose electrons in the silicon. That flow creates electricity that can be used in your home.

Photovoltaic panels

Individual photovoltaic cells are wired together to make the solar panels that go on your roof. These panels are typically joined together in larger solar arrays to provide more power. The current flows through the panels into an inverter, which converts it into electricity that you can use inside your home. Different types of panels are available. Homeowners with limited space might choose monocrystalline silicon photovoltaics, which are the most efficient available (but also a little more expensive). Polycrystalline silicon panels are a little bigger, but less expensive. Some people choose to forgo panels altogether and use solar shingles, which are designed to look like regular shingles on your roof (unfortunately, they’re a lot less efficient, so for most people, bigger panels are a better choice).

What are the advantages of photovoltaics?

Every hour, the amount of solar energy hitting the Earth is greater than all the electricity humans use in a year. That’s a lot of power, and the sun doesn’t charge for it. After you’ve paid for your solar panels, you’re essentially getting free energy. Solar incentives (like the federal solar tax creditSRECs, and state and local rebates) are making this a great time to invest in panels. The environment will thank you, too: getting electricity from solar panels is a great way to fight climate change, since coal power plants are the biggest source of CO2 emissions in the U.S. Coal power plants are also terrible for health, since coal pollution can cause (and worsen) asthma, bronchitis, and even cancer. Want to go solar? Sign up (it’s free!) to see deals on solar in your area.