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What Are Photovoltaics?

By: James Murray-White - Updated: 1 Jan 2013 | comments*Discuss
Photovoltaics Cells Convert Light

Photovoltaics are cells made from glass and steel that convert light into electricity. Inside the core of the cell are components known as photodiodes, which feed the incoming solar rays into semiconductors, which react with the sunlight, thus converting to electricity.This is an extremely effective way of harnessing power from the sun, and using a plentiful and renewable resource as an energy source, instead of relying on environmentally-damaging and limited fossil fuels.

Worldwide Applications of Photovoltaics
The worldwide use of photovoltaic systems is increasing annually, with Germany, Japan and the US leading in research and use of. As an example, in Germany at the end of 2005, there was a total of 1,429,000 PV wattage capacity (KWp) (combining both off-grid system an on grid figures). In contrast, for the same period in the UK, the figure was 10,877 KWp.

The first large-scale use of photovoltaic systems as a power source was in powering satellites orbiting the globe. Other commercial uses include roadside breakdown assistance telephones, remote sensing systems, and the protection of underground pipeline systems, by powering cathodes that prevent corrosion of the pipes metal surface. The public probably first became aware of the application of photovoltaics through their use in powering personal calculators, pioneered in the 1970's. A recent, very useful and innovative gadget on the market is a photovoltaic mobile phone (and Ipod, laptop etc) charger – these portable, fold-out devices are worth the investment, and really show that there are alternatives to our increasing gadget-driven energy consumption in the Western world.

Photovoltaics in a Sustainably-Built Construction
The CIS Tower in Manchester, an office complex housing the Innovative and ethical Co-operative Bank and financial services, is covered in photovoltaic cells, and is the largest PV project in the UK. The project cost 5.5 million pounds in 2005, and is estimated to generate 180,000 Kwh per year, which is fed directly into the National electricity grid. This gives enough power to run approximately 73 homes – all year round; all their energy needs met through harnessing the sun.

On this kind of scale, photovoltaics is a significant contributor to energy collection, storage, and use. However, on a small-scale, per building level, the costs are prohibitive, and storage of converted electricity becomes a problem. The cost per unit is equally a prohibitive factor, and unlike the small household wind turbines, recently on the market at DIY stores, it is not possible to simply buy a unit, attach it, and connect up to the National Grid, or use the power exclusively in the home. This situation is changing however, due to concerns over depleted fossil fuels and the growing interest in alternative and renewable energies, so check with your local Energy Saving Trust (EST) or green architect or building suppliers.

Houses in remote areas of the UK, where it is difficult to get cables to, are sometimes given financial help to design and erect a photovoltaic system, but these examples are few. Photovoltaics can play a part in the make-up and powering of a sustainably built building: however they are expensive, and might be best considered as part of a wide package of renewable energy sources, that could also include passive solar design, and energy from wind, as two examples.

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