Introduction

Engineers estimate that sunlight could provide 10,000 times the amount of energy needed to fulfill humanity's current needs. The challenge is, and has always been, to find ways of capturing this abundant energy cost effectively.

Making solar power attractive

Although the energy source is free, the materials used to make solar or photovoltaic cells, such as copper and high-grade silicone, are relatively expensive. Although in real terms, the technology today is 90% cheaper than it was in 1970s, when solar enjoyed its first wave of mainstream popularity, in part in reaction to the 1973-4 oil-price crisis, solar energy still costs around 5 – 10 times more than energy from coal.

However, a number of factors are conspiring to make solar a far more attractive proposition: growing awareness of climate change, the need for Governments to achieve emissions targets and, more recently, the increasing, and increasingly unpredictable, price of fossil fuels.

Countries investing in solar power

Spain has been a major investor in this area for some time, both at home and internationally, and in 2007 launched Europe’s first commercial solar power tower system. Based near Seville, this 11MW facility will be expanded to produce 300MW by 2013.

A more surprising development perhaps is Germany becoming a global ‘solar power’, second only to Japan. An incentive scheme introduced in 1999 means households can sell electricity generated by their home solar cells back to the grid at a guaranteed premium, approximately four time market rate, guaranteed for 20 years.

By giving consumers the confidence to invest, Germany has seen demand soar and the value of its solar industry grow from €450m to €4.9bn over the past six years. 50,000 people are now employed in the sector and this figure is expected to grow to 200,000 by 2020.

How does solar work?

Photovoltaic cells consist of one or two layers of semi-conducting material, such as silicon. Light falling on the cell creates an electrical field as photons from the suns’ rays knock electrons loose from silicon atoms. This ‘flow’ of electrons produces electricity.

Cells are rated in terms of the power they produce in full sunlight – known as the kilowatt peak (kWp). It is estimated that each kWp saves circa 455kg of carbon emissions per year from conventional energy sources.

Recent developments in solar power

Recent developments have focused on concentrating the sun’s power using rows of mirrors, tracking the sun throughout the day, to heat water in a ‘power tower’ to 1500 degrees Celsius. This turns a steam turbine, producing electricity. This ‘solar thermal’ approach is being used in large scale solar arrays in the US and Spain.

Case study: Commercial solar power in action

Solarcentury worked on a £5.5 million project to turn Manchester’s CIS Tower, a noted local landmark, into the largest commercial solar façade in Europe. Read the case study of commercial solar power in action.