LOOKING TO THE FUTURE: Photovoltaics

Photovoltaic technology uses devices called solar cells to change light energy directly into electrical energy. There are no magnets, pistons, or turbines. There are only the solar collectors and wires.

This technology was discovered in the nineteenth century, and was developed in the 1960s to power satellites orbiting in space. The technology was slow to catch on for everyday use because the photovoltaic cells were so expensive to produce. In the 1950s, a photovoltaic generating system cost about $2000 per watt of power. Today the cost is about $5 per watt, and is still dropping.

Photovoltaic cells are currently used in small applications like calculators and wrist-watches; in medium-sized arrays that power highway lighting, recreational vehicles, and off-the-grid homes, and in large arrays owned and operated by power companies.

Many different companies are working to increase the efficiency and to bring down the cost of this technology. At this point, solar cells are about 10% - 20% efficient. About 10% or 20% of the solar energy that strikes a photovoltaic collector is converted into electrical energy. But even this low efficiency makes photovoltaics the right choice for many situations. After all, the sun's energy is free, abundant, and perfectly clean.

Take a tour through a photovoltaic system