Appliance Science: How solar panels convert light into electricity

CNET: Appliance Science: How solar panels convert light into electricity

It sounds like magic: capturing energy from the sun and converting it into electricity to run your toaster. It's science, not magic, though. Solar panels use a curious bit of science called the photovoltaic effect to convert one form of energy into another. Here's how solar panels harvest light, converting it into electricity.

The sun is an intense powerhouse, outputting in the region of 10 decillion (that's a 1 followed by 34 zeroes) joules of energy per year. That's a lot. The whole planet is bathed in this wash of energy, and it is one of the things that makes this such a pleasant place to live. It drives the weather, heating the atmosphere and making life possible. So, wouldn't it be useful to be able to convert some of this energy into a form that we could use?

That's what plants do through photosynthesis, using light to combine carbon from the atmosphere into sugars that they metabolize to grow. And the solar panels that you see on an increasing number of roofs do something similar, converting light into electricity. They can do this because of something called the photovoltaic effect, which converts solar energy into electrical energy.

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CREATIVITY-ONLINE: These Sun Hats Bring Solar Power to a Head Near You

Who wouldn't want their own solar sun hat? Especially if you live in a part of Colombia so remote that there is no electricity, and people walk home in the dark and light their dwellings with candles.

Colombia's biggest utility company EPM is starting a solar energy program. To kick it off, EPM and DDB Colombia decided to harness the blazing sun people in isolated communities toil under all day. They already have the habit of wearing hats, so EPM gave them new ones called Sun Hats.

Each hat has two little solar panels that are fully charged by eight hours of sun. At night, they turn into flashlights similar to a miner's headlight to provide four hours of light.

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UNION OF CONCERNED SCIENTISTS: One Million Solar Energy Systems Now Turned On in US

Around the country, solar advocates are cheering. One million solar installations(including nearly 950,000 rooftops) are now turned on somewhere in the US, a symbolic milestone signaling a fundamental change in the energy landscape.

What are the implications of all this?

Let’s look at some of the answers.

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VOX: Solar power is contagious. These maps show how it spreads

Rooftop solar is expanding rapidly in the United States — by some estimates, a new system goes up every four minutes. There are plenty of reasons for that, from falling prices to generous federal subsidies to innovative leasing schemes.

But there's another, little-discussed factor here: Residential solar power is contagious. Yep, contagious. Studies have found that if you install solar photovoltaic panels on your roof, that increases the odds that your neighbors will install their own panels.

SolarCity, the largest solar installer in the United States, just published some fascinating data on this "contagion" effect. The company has installed 230,000 rooftop systems nationwide (often by allowing customers to lease panels rather than buy them upfront). It says fully one-third of customers were referred by a friend or neighbor.

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