Solar Cell

The humble Solar Cell is not as new as we may think because it first began its life with the work of the French physicist Antoine-César Becquerel in 1839. Becquerel discovered the photovoltaic effect while experimenting with a solid electrode in an electrolyte solution; he observed that voltage developed when light fell upon the electrode.

About 50 years later, Charles Fritts constructed the first true Solar Cell using junctions formed by coating the semiconductor selenium with an ultra thin, nearly transparent layer of gold. Fritts's devices were very inefficient, transforming less than 1% of the absorbed light into electrical energy.

By 1927 another metal semiconductor-junction Solar Cell, in this case made of copper and the semiconductor copper oxide, had been demonstrated.

By the 1930s both the selenium cell and the copper oxide cell were being employed in light-sensitive devices, such as photometers, for use in photography. The early Solar Cells, however, still had energy-conversion efficiencies of less than 1%.

This impasse was finally overcome with the development of the silicon Cell by Russell Ohl in 1941. But then in 1954, three other American researchers, G.L. Pearson, Daryl Chapin, and Calvin Fuller, demonstrated that silicon Solar Cells were capable of a 6% energy-conversion efficiency when exposed to direct sunlight.

By the late 1980s silicon cells, as well as those made of gallium arsenide, with efficiencies of more than 20% had been fabricated. In 1989 a concentrator Solar Cell, a type of device in which sunlight is concentrated onto the cell surface by means of lenses, achieved an efficiency of 37% due to the increased intensity of the collected energy.

In general, solar cells of widely varying efficiencies and cost, are now readily available although as with any Solar Panels there are certain limitations for consistent power generation. However, there are ongoing improvements in technology as industry strives to eliminate Solar Power Limitations.

(Article courtesy of encyclobeamia.solarbotics.net Author Eric Seale)

The official description of Solar Cells is this;

'any device that directly converts the energy in light into electrical energy through the process of photovoltaics'.

How this is done can be seen from the main structure of a most commonly used cell shown below, the absorber layer and the back junction layer are both made of the same material.

Typical Configuration of Solar Cells

Both batteries and fuel cells use chemical reactions to produce electricity and generators have moving parts to do the same work. However, unlike both of these processes the Solar Cell has no moving parts, no chemicals but converts the sunlight into electrical energy.

This in itself makes this type of Solar Energy an environmentally friendly solution to gaining access to electricity, (sunlight is also free).

An individual cell can be used on its own as seen in such tings as small calculators and the like, or they can be grouped together in what's known as 'arrays'. These arrays can be made up of many thousand individual cells and used as a central power station the same way a coal/oil fired and nuclear power stations are used.

One issue with collecting power from Solar is that for a consistent flow of electricity there is need for a Power Back up so as to supply power in times of no sun

A grouped Solar Cell which is configured smaller are commonly referred to as Solar Panels, these are used extensively in remote areas where power is not connected and can be found running water pumps in desert areas and navigational, equipment at sea.

We can also see this technology being used for certain street lighting and road safety signs where the cost is prohibitive if power from the grid were to be installed. Even public phones in remote areas and emergency telephones are using this type of technology.

Solar Panels are used extensively in space because of having no moving parts requiring maintenance. As a consequence, most space satellites, including communications and weather satellites, are Solar Powered.

Needless to say the commercial sector has fully embraced Solar Cell technology by using them in children's toys, calculators, communications and so on, the list is endless and no doubt has not yet ended.