Special Applications of Solar Power

Professional Application

Ocean navigation aids: many lighthouses and most buoys are now powered by solar cells.

Telecommunication systems: radio transceivers on mountain tops or telephone boxes in the country can often be solar powered.

Remote monitoring and control: scientific research stations, seismic recording, weather stations, etc. use very little power which, in combination with a dependable battery, is provided reliably by a small PV module.

Cathodic protection: this is a method for shielding metalwork from corrosion, for example, pipelines and other metal structures. A PV system is well suited to this application since a DC source of power is required in remote locations along the path of a pipeline.

Electric power generation in space

The best choice for providing electrical power to satellites in an orbit around the Earth has been and will remain photovoltaic solar generators. Solar cells on the U.S. satellite Vanguard I in 1958 demonstrated the first practical application of photovoltaics. Since then, the satellite power requirements have grown from a few Watts to several kilowatts. Arrays approaching 100 kW are being planned for a future space station.

In the adverse conditions of space environment, a space solar array must be extremely reliable. It is very expensive to lift every kilogram of weight into the orbit, so the space array should also have a high power-to-weight ratio.

Solar-powered vehicles

Solar-powered vehicles and the technology is developing rapidly due to large research interest. Solar-powered cars are becoming common at solar races like the World Solar Challenge and at car and technology shows. Solar boats have also made an appearance.

Cars can use a variety of solar cell technologies, but they usually use polycrystalline silicon, monocrystalline silicon, or gallium arsenide. The cells are wired together into strings while strings are often wired together to form a panel. Panels normally have voltages close to the nominal battery voltage. The main aim is to get as many cells in as small a space as possible. These cells are encapsulated to protect them from the weather and breakage.

It is more difficult to design a solar array than to just stringing bunch of cells together. A solar array acts like a lot of very small batteries all hooked together in series. The problem is that if a single cell is in shadow it acts like a diode, blocking the flow of current for the entire string of cells. Array designers try to correct this by using by-pass diodes in parallel with smaller segments of the string of cells, allowing current to flow around the non-functioning cell or cells. Another consideration is that the battery itself can force current backwards through the array unless there are blocking diodes put at the end of each panel.

The weather conditions, the position of the sun and the capacity of the array all effect the amount of energy one array can collect. At noon on a bright day, a good array can produce over 2 kilowatts (2.6 hp).



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