Solar Panels

Solar panels are devices that convert light into electricity. Most of the time, the most powerful source of light available is the Sun, called Sol by astronomers. Some scientists call them photo-voltaics which means “light-electricity.”

A solar panel is a collection of solar cells. Lots of small solar cells spread over a large area can work together to provide enough power to be useful. The more light that hits a cell, the more electricity it produces. Spacecraft are usually designed with solar panels that can always be pointed at the Sun even as the rest of the body of the spacecraft moves around, much as a tank turret can be aimed independently of where the tank is going.

The solar panels are made of solar cells. A cell is a small disk of a semiconductor like silicon. They are attached by wire to a circuit. As light strikes the semiconductor. Light is converted into electricity that flows through the circuit. As soon as the light is removed, the solar cell stops producing power.

Solar panels are very hardy. Compared to alternative power sources, they wear out very slowly. Their effectiveness decreases around 1 to 2 percent a year. This means after a five year mission (boldly going where no probe has gone before), the solar panels will still be making more than 90% of what they made at the beginning of the mission (as long as they haven’t gotten farther away from the Sun).

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