Silver Coatings with Protective Transparent Films for Solar Concentrators

Historic

212 BC, Archimedes used mirrors for the first time to concentrate the Sun’s rays. In 1615, a small solar powered motor was developed by Salomon De Caux, this motor consisted of glass lenses and an airtight metal vessel. Lavoisier and Joseph Priestley developed the theory of combustion by concentrating solar radiation on a test tube for gas collection. In 1878, Paris, a small solar power plant was exhibited; the plant was made of parabolic dish concentrators. The first CSP was installed in 1913, in Egypt as a parabolic trough solar field for pumping water. Because of the oil crisis in 1970s lot of pilot CSP plants were built. Then, the first commercial CSP was operated in California, USA (1984-1991) It was not until 2006 that interest was once again rekindled for the development of large scale CSP plants. (Behar, Khellaf, & Mohammedi, 2013).

The central solar thermal electricity produced concentration similarly to conventional power plants: using steam to drive a turbine. The difference between them lies in the origin of energy instead of fossil fuel using solar radiation. Solar concentrators with tracking systems focus a large area of sunlight onto a small area. Thus, four main elements are required: Solar concentrator, receiver, some form of transportation or storage, and power conversion.

Techniques use solar radiation to electrical energy conversion using an intermediate conversion into thermal energy are classified into two groups: those that concentrate solar radiation along a line and concentrate solar radiation at a point. For linear concentration, two technologies that are used: parabolic trough and linear Fresnel reflector. Pointed concentration, with much higher concentration ratios and the ability to track two axes, there are two applicable technologies: the central tower and parabolic dish using Stirling engines (Fend et al., 2003).