“Solar shingles on a home in San Diego, Calif. See more pictures of green living.Sandy Huffaker/Getty Images
You’ve probably seen solar panels on the rooftops of houses or office buildings, but have you ever seen solar shingles up there? If you have, chances are you didn’t know it.
Solar shingles are an integrated photovoltaic (PV) building product, which means they directly generate electricity from sunlight. They’re made with specific materials that naturally undergo an electronic process in the presence of sunlight.
From a distance, they look like ordinary roof shingles. But up close, it’s obvious they’re more than that. Solar shingles are used on the roofs of commercial and residential buildings to generate electricity, and some models can convert the electricity to heat.
Solar shingles are made of the same materials as those used in regular solar panels, including wire, a photosensitive waterproof product to protect the roof from outdoor elements, and material that can generate an electric current in sunlight.
In fact, solar shingles and solar panels operate the same way and are overall quite similar. The main difference between them is cost. Solar panels have one function: They generate electricity. But solar shingles serve a dual purpose — they generate electricity and act as shingles, which makes them less expensive in the long run.
If you’re curious how solar shingles work, turn to the next page to learn about their interesting technical aspects.
Solar Shingles 101
Solar shingles have a special property that allows them to make electricity from sunlight. Let’s break down the scientific process behind how this works.
A photon is a unit of electromagnetic radiation with no charge; Its protons (positively charged subatomic particles) and electrons (negatively charged subatomic particles) are equal, giving it no charge. The photon, here, is a particle of sunlight. Sunlight strikes a solar shingle coated with a special surface that naturally knocks off an electron from the particle of light. The freed electron travels through an electrical circuit to an area where other electrons are stored. This collection of electrons is then harvested to generate a current. This is how all solar electricity works, whether it’s a solar shingle, solar panel or something else. Photovoltaic (PV) devices like these can be used to power anything from a calculator to a skyscraper.
Solar shingles, in theory, can produce 100 percent of a building’s electricity usage, but it depends on a number of factors: the demand of a building, the amount of sunlight the structure gets at that particular geographic location, the building’s current utility rates and availability of sufficient space on the roof that opens to southern skies.
Solar shingles can work practically anywhere (even in gray-weather places) because they can use diffused, scattered sunshine on overcast or even rainy days. In fact, the country with the most buildings that use PV devices is Germany, and the American Solar Energy Society (ASES) says that all 50 states in the US get better sunlight than Germany.
But what if you live in a sunny place where there is ample sunlight year round? Can your solar shingles produce too much power? Yes, and this is good news. When this happens, your excess energy is sent to the electric grid, and you usually receive a check from the electric company or a credit on your next utility bill. Jurisdictions differ in how they address excess energy, so check with your electric company to find out how this process works in your area.
Tax incentives
Currently, the U.S. federal government provides a $2,000 tax deduction for homeowners to put a PV device on their houses, including solar shingles, and a $2,000 credit if they put in a solar hot water or solar thermal unit. Some states and local jurisdictions offer their additional incentives
Installing Solar Shingles
Solar shingles are about the same size as a typical roof shingle, while solar panels are flat, rigid panes often several square feet. It’s because of this size difference that installation of solar shingles is much more labor-intensive — more shingles are needed to complete a job compared to the number of panels required for the same project. Installers tediously put in one shingle after another after another and wire each one inside the building. If you decide to get solar shingles, always hire a professional certified by a reputable certifying group, such as the North American Board of Certified Energy Practitioners, International Brotherhood of Electrical Workers or state or trade organizations.
Photovoltaic (PV) installations cost between $9 and $11 per watt. An average system will range from $15,000 to $30,000 (after incentives). Price is affected by the size of your PV system and the amount of sun and shading in your location.
The time it takes to do an installation varies and is affected by roof space, the number of people in an installation crew and the status of the building (re-roofing verses new construction). Once all the solar shingles are put in and wired together indoors, under the roof, the installer applies for a permit to connect your system to the electric grid.
Needless to say, homeowners can’t (or shouldn’t) attempt installation on their own. However, the industry is changing, and five to 10 years from now, homeowners may be able to safely and easily "plug and play," according to the American Solar Energy Society (ASES). For this to happen, more sophisticated infrastructure would have to be in place, specifically, smart meters and a smart grid, which don’t yet exist. Here’s how it would work: The homeowner would plug his or her solar shingles into a smart meter — a meter with plug-in ports for solar electric applications like solar shingles. Through this special meter, they could hook up to the electric grid.
The next page has even more information to take your roof solar, as well as other ideas to make your home energy efficient. Enjoy all that money you’ll save.
Lots More Information
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Sources
- Collins, Brad. Executive Director of the American Solar Energy Society. Personal interview. April 30, 2009.
- Stanley, Tomm. "Going Solar: Understanding and Using the Warmth in Sunlight." Stonefield Publishing. 2004.
- The American Solar Energy Society. http://www.ases.org (April 30, 2009 and May 2, 2009)
- The Solar Energy Industries Association. http://www.seia.org (April 30, 2009 and May 2, 2009)
