Look at the calculator on your desk. Chances are the sun powers your calculator. Just check for the familiar small, dark gray panels on the front of the calculator. If they are there, your calculator operates with solar panel technology.
How does that little solar cell help you do your job? It uses photovoltaic cells. Photovoltaic (PV) is combination of the words that mean light (photo) and electricity (voltaic). Photovoltaic cells or modules (groups of cells) convert the light of the sun directly into electricity. It may seem exotic to use photovoltaic cells to power a small hand calculator, but solar panel technology is being applied to more common uses every day.
Here's how PV cells turn sunlight into electricity. They are made of materials called semiconductors. A frequently used semiconductor is silicon. When the sun strikes the semiconductor, the silicon soaks up some of the light. This transmits the energy within the sunlight to the semiconductor.
The energy breaks the electrons free, permitting them to flow unrestricted. To make something useful of all these free-floating electrons, the cells use electric or magnetic fields that drive the free electrons to flow like river, creating a current.
By inserting metal contacts at the top and bottom the PV cell, we can extract the current to power something outside the cell, like your calculator. The total wattage (or power) is determined by the extracted current added to the cell's voltage.
Advances in solar panel technology may actual see the panel itself disappear. The newest and most promising advance is the dye-sensitized solar cell (DSC) technology. Michael Grätzel, a chemist at the Swiss Federal Institute of Technology, pioneered DSC, also called Grätzel cells, in 1991.
DSC is designed in layers: a photosensitive layer composed of nano-sized, ultrathin semiconductor crystals over a fine layer of titanium dioxide. When sunlight hits the photosensitive layer, the loose electrons collect on the layer of titanium dioxide and produce an electrical current. A dye made of amorphous organic material covers the titanium dioxide -- the dye absorbs sunlight and attracts free-flowing electrons, which creates a charge.
DSC lends itself to thin layers of photosensitive film. This transparent, lightweight, flexible and low-cost, sheets or dye film can be applied to the windows of your house or car, even to your sunglasses. The film generates a charge that can be applied to a small battery to power anything, including your phone or MP3 device.
The military even has applications for the DCS technology. The film can be applied to tents to power lights and laptops. In larger applications, it could power entire command centers. It could cover backpacks or be made into wearable solar panels and power a soldier's electrical devices, eliminating the need for bulky and heavy supplies of batteries.