Solar Photovoltaics

Solar Cells

Various types of solar cells

Solar cells, also called photovoltaic (PV) cells by scientists, convert sunlight directly into electricity. When sunlight (a form of energy) hits the solar cells inside a solar panel, it excites the electrons of a material (usually silicon) inside the cell. This reaction creates electron flow that is turned into electricity.

Solar cells were first being used to power space satellites and smaller items such as calculators and watches.  Today, thousands of people power their homes and businesses with individual solar PV systems.  Utility companies are also using PV technology for large power stations.

Uni-Solar building-integrated solar shingles.

Traditional solar cells are made from crystalline silicon, are usually flat-plate, and are generally the most efficient. Second-generation solar cells are called thin-film solar cells because they are made from amorphous silicon or nonsilicon materials such as cadmium telluride. Thin film solar cells use layers of semiconductor materials with thickness of only a few micrometers. Because of their flexibility, thin film solar cells can double as rooftop shingles and tiles, building facades, or the glazing for skylights. Third-generation solar cells are being made from a variety of new materials besides silicon, including solar inks using conventional printing press technologies, solar dyes, and conductive plastics.

Examples of solar panels

Solar PV Panels

Solar panels used to power homes and businesses are typically made from solar cells combined into modules that hold about 40 cells. A typical home will use about 10 to 20 solar panels to power the home. The panels are mounted at a fixed angle facing south, or they can be mounted on a tracking device that follows the sun in order to capture the most sunlight. Many solar panels combined together to create one system is called a solar array. For large electric utility or industrial applications, hundreds of solar arrays are interconnected to form a large utility-scale PV system.

What Can You Do with Solar PV Panels?

A Sharp 4.9kW grid-tied PV system installed at a local Knoxville residence by Green Earth Services

Rising energy prices and growing environmental concerns are making solar electric systems more attractive to homeowners and business owners. A solar electric system reduces high energy costs and keeps your home or business up and running during power outages.

While the capital cost of installing photovoltaic equipment is high, the fuel (sunlight) is limitless and free. In addition, solar PV panels provide an excellent way to add value to your home. Many financial institutions are even providing the option of including the cost of PV systems into new home mortgages, making them  easier to finance. A solar system will provide the biggest benefit and the quickest payback to customers who have already diligently retrofitted their homes with energy efficiency measures.

When considering adding solar PV panels to your house or business building, you need to think about what types of PV panels will best suit your needs. Other questions that you may want to ask include whether there is a south-facing roof on your building, whether the aesthetics of the building are important to you, and what kinds of federal and state incentives are available to you.

The National Renewable Energy Laboratory (NREL) developed a program called In My Backyard (IMBY), which can estimate the electricity you can produce with a solar photovoltaic (PV) array at your home or business. Learn more here.

Learn more about how to go solar.

Download DOE’s guide to consumers on how to own solar PV systems.