Solar energy – power from the sun – is free and inexhaustible. This vast clean energy source represents a viable alternative to the fossil fuels that currently pollute our air and water, threaten our public health and contribute to global warming. In a broader sense, solar energy supports all life on earth and is the basis for almost every form of energy we use. The amount of energy received from the sun that falls on the Earth’s surface is enormous. All the energy stored in Earth’s reserves of coal, oil, and natural gas is matched by the energy from just 20 days of sunshine.

Solar energy can be converted to useful work or heat by using a collector to absorb solar radiation, allowing much of the Sun's radiant energy to be converted to heat. This heat can be used directly in residential, industrial, and agricultural operations; converted to mechanical or electrical power; or applied in chemical reactions for production of fuels and chemicals. Solar energy part of the renewable energy generated worldwide and accounts for just over 2 per cent of the whole electricity generation. Hence there is huge potential for the development of technology for solar energy. The solar market grew by an average of 15 per cent annually during the 1990s, the grown rate that is expected to continue as costs decline and new markets open up.

Some of the successful solar energy projects in different parts of the world are a good example of reducing carbon emissions and producing clean energy. Solar energy is light and heat energy from the sun. This vast amount of energy is more than 23,000 times that used by the human population of this planet. Solar energy can be captured by solar panels. There are two main types of solar panels which use complete different technologies to make use of the energy from sun.

• Solar water heating collectors - these panels absorbs the energy from the sun and transfers it to heat water. Solar Power Solar water heating systems are the most popular form of solar energy used in the UK. There are 2 types of solar water heating collector: flat plate and evacuated tubes.

• Photovoltaic or solar electric panels – these panels transform the solar from radiation directly into electricity. Photovoltaic (PV) or solar electric can offer us all the ability to generate electricity in a clean, quiet and renewable way. The variety of applications for solar electric are numerous. Photovoltaic (PV) cells are used in simple applications e.g. calculators and watches and also for domestic and larger applications. Large PV systems can be integrated into buildings to generate electricity for export to the National grid.

For maximum efficiency, solar panels should be mounted on a south facing roof at a 30 degree angle with the horizontal and away from any shadows from tress, surrounding buildings or chimneys. Solar technologies are used in watches, calculators, water pumps, space satellites, for heating water and supplying clean electricity to the power grid. There is enough solar radiation, striking the surface of the earth to provide all our energy needs.

Solar technology has spread throughout the world and there are large solar projects planned and being built in Portugal, China, the UK, India and other countries. A plan to build the world's biggest solar energy power station, covering about 250 hectares and capable of sustaining 130,000 households, has been unveiled in Portugal at an abandoned mine near the town of Beja, in the southern Alentejo region. With a potential output of 116 megawatts, the new station would be several times the size of what is now the world's largest solar energy plant. The output would be fed into the Portuguese electricity grid at a government-set price.

China invested £3.3bn in renewable energy last year, making it one of the biggest investors in renewables in the world. There are 30 million solar households in China, which account for nearly 60 per cent of global solar capacity. Local government officials in Dunhuang in Gansu province said they would build the world's biggest solar plant there, a 100-megawatt project costing £400m that will take five years to build. In fast-moving Shanghai, China's biggest city and its financial hub, hundreds of thousands of householders are using solar panels to heat the water for their morning showers.

In the UK, the CIS Tower in Manchester, the city’s tallest building is on course to be the biggest user of solar panels in the UK. In India, the Tata Group and BP set up Tata BP Solar Ltd, with the aspiration to improve quality of life throughout India and the world with clean energy.1

Solar energy technologies are poised for significant growth in the 21st century. More and more architects and contractors are recognizing the value of passive solar and learning how to effectively incorporate it into building designs. Many offer rebates, production incentives, and tax incentives, as well as loan and grant programs. Solar energy will play an increasingly integral role in endinsg dependence on fossil fuels, combating the threat of global warming, and securing a future based on clean and sustainable energy. 2

Notes

1. P. Brown, ‘Global Warning: The last chance for change,’ Dakini Books NP (2006) p.309
2. Union of Concerned Scientist, How Solar Energy Works,
http://www.ucsusa.org/clean_energy/renewable_energy_basics/how-solar-energy-works.html