Skylight substitute harvests solar power and reduces overheating
Diamond-Power skylight panels are designed to harness solar energy, while reducing the solar heat load on buildings
There's no doubt that skylights make for psychologically-nicer buildings, while also reducing the amount of electricity required for daytime artificial lighting. If they let in too much sunlight, however, they can actually increase the amount of electricity needed for air conditioning. California-based EnFocus is attacking the situation from two ends - its Diamond-Power panels diffuse sunlight to keep interior heat down, while also harnessing it to create electricity.
Designed for use in commercial buildings, each weatherproof panel is about the size of a regular skylight, and weighs 100 pounds (45 kg). A series of small lenses in each one focus the sunlight by 400 times, onto strips containing high-efficiency gallium arsenide photovoltaic cells. These lenses are also mounted on a dual-axis tracker, which allows them to pivot with the Sun throughout the day.
Each panel has an electrical output of 288 watts, which the company claims results in 720 kilowatt-hours of power generation annually, while also providing 1,490 kWh-worth of lighting. Additionally, each panel reportedly reduces a building's heat load by 2.1 MBTU (million BTUs) per year ... we can assume these figures are for sunny California.
All told, EnFocus states that its Diamond-Power panels can reduce a building's electrical bills by up to 50 percent, and should pay for themselves within five years. Those figures were apparently enough to impress Google, which is testing the panels at one of its Silicon Valley offices.
Other solar-power-harvesting window products include Ensol's spray-on film, Pythagoras Solar's photovoltaic glass units, and New Energy Technologies' Solar Window.
Source: Clean Energy Authority
About the Author
An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.
All articles by Ben Coxworth
Surely if a roof lets in too much light, use self adjusting venetian blinds. Another cheap way to cool a roof is by spraying it with water.
The unit MBTU was defined as one thousand BTU, presumably from the Roman numeral system where \"M\" stands for one thousand (1,000). This is easily confused with the SI mega (M) prefix, which multiplies by a factor of one million (1,000,000). To avoid confusion many companies and engineers use MMBTU to represent one million BTU.
Despite what Wikipedia says, the company is using MBTU to mean million BTU.
Actual skylights also save on bulb life. Prisms also allow you to choose to direct the infrared, and UV light in or out.
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