If you have often wondered what powers most satellites and other small space craft, the answer is energy from the sun. The majority of geostationary satellites feature solar panels that point in the sun's direction. As the efficiency of photovoltaic cells based in space is far greater than here on earth, thanks to the lack of atmospheric interference, they are the perfect source of renewable energy.
A panel is made up of many individual cells. Each cell own it own produces a small amount of energy, when the cells are placed together in an array, the amount of electricity that is generated can be enough to power various motors and other components on orbiting space craft.
Most satellites features panels that rotate to track and follow the sun, by maximizing the amount of sunlight they are exposed to, they can then work more efficiently. A typical satellite would have been designed in such a way that the photovoltaic equipment moves independently of the rest of the spacecraft, to increase the amount of sunlight that is captured. This is a design that has been in use for many decades, in fact solar energy was used in satellites much earlier than it was adapted for use here on earth.
Conversely, it is also possible for a satellite to orient the photovoltaic device to ensure that too much energy is not captured. This safeguard ensures that the various components do not overheat and cause damage to delicate circuits.
Solar energy is thought of as being extremely cost effective in space craft as compared to other power sources. The panels are built to last for decades, or sometimes even longer, the only potential damage that may be caused is due to collision with space debris.
The amount of energy that can be produced by photovoltaic cells above the atmosphere depends in part on solar radiation. Research has found that those satellites in a relatively low orbit suffer a decline in efficiency of the PV cells by around two to three per cent each year.
Photovoltaic concentrators have been used in the design of non terrestrial solar systems for many years. These are mirror like devices that help to focus the sunlight on a specific area, thus increasing the overall efficiency of the panel. The principle is the same as when we use a mirror or magnifying class to focus the sun's rays on paper or kindling to light a fire, and is not too dissimilar to the way a lighthouse beam is enhanced to be seen over a long distance
A PV concentrator helps to reduce costs whilst increasing efficiency. It is a concept which is now being adapted for use here on earth. As there are new advances in the energy systems used on satellites and other orbiting craft, there will also be the opportunity for the technology to be integrated into earth based systems. With fossil fuel resources predicted to start running out in the near future, utilizing the sun's energy will take on a greater importance.
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