The sun's power can be felt on earth - even at a distance of 93 million miles - as both heat and light. Photovoltaics is the technology which generates electrical energy 'fuelled' simply by light. First identified over 150 years ago, photovoltaics (also known as PV) became known during the 1960's providing power in Space for the NASA programmes. Since then it has been well established on Earth powering remote industrial equipment for Telecommunications, Cathodic Protection of Pipelines, navigational aids etc. as well as bringing power to the two fifths of the world's population (55 billion people) with no access to electricity.

These uses for photovoltaics tend to occur where there is plentiful sunlight, as well as heat. It has led to the belief that PV needs tropical sunlight, whereas in fact it works in bright daylight in Northern Europe. The Scolar Programme demonstrates PV working in British weather conditions, and provide evidence for the role it can play in a country with a well developed national electrical grid.

During the 1990's unease has developed internationally about the dangers of global warming, as well as the squandering of the earth's fossil fuel resources. Photovoltaics has an increasingly important part to play as a contributing fuel to the energy mix of the future, particularly in the industrialised world interfacing with a national grid. It is an ideal energy source for the urban environment. Power is generated silently, unobtrusively and without movement from the structure of a building with none of the transmission or distribution problems of other renewable power sources such as wind and wave energy. If all the 'unused' roofs and walls of buildings were clad with photovoltaics it could contribute to the emerging 'energy gap' where demand for power outstrips acceptable supply.

Photovoltaics can be manufactured using a wide range of production methods. The technology used in space produces the maximum power per unit area at a high cost. For use on earth much research has taken place to find the optimum balance between cost and power output. The first generation technology used after the space programmes uses silicon (which is found in sand) as crystals cut into thin wafers and connected side by side. The silicon is either from a single crystal or made up of a number of crystals ('mono or polycrystalline'). Other technologies lay the active material in very thin layers on a substrate such as glass ('thin film' technology) which has benefits in terms of manufacture, and thus the opportunity to reduce prices through increased volume. The two technologies which have achieved most impact in the market are based on silicon and cadmium.

The Scolar Programme is in tune with current trends for development of photovoltaics by using the available technology and getting it better known. People need to see and understand how the technology works - whether or not governments provide incentives - before they are likely to incorporate it in their lives. Scolar has enabled this essential first step on the way to the widespread use of solar electricity in Britain.

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