Solar Energy - Energy from the Sun

Several scientific works have concluded that the Sun is the central and the largest part of our solar system, making up about 99.8% of the entire system. It's mass is about 330,000 times the mass of the planet Earth and has a diameter of about 1.5 x 10⁶ Km. It is about 1.5 x 10⁸ Km away from the Earth and yet has a very powerful influence on life on Earth.

The Sun's surface temperature is about 6,000oC, while the temperature of the core is about 1.4 x 10⁷oC. The temperature of the Sunspots (the coolest regions of the Sun's surface) is about 4,000oC The luminosity (the amount of energy emitted by a star each second - Sun often considered as a star) of the Sun is about 3.9 x 10²⁶ Watts.

The Sun releases considerable amount of light and heat to the planets and stars of the solar system. The Earth receives about 1.74 x 10¹⁷ W) of solar radiation from the Sun at the upper atmosphere. Thirty percent (30%) of the solar radiation is believed to be reflected back while the remaining seventy percent (70%) are absorbed by the atmosphere, oceans and land masses. The absorbed energy is in the order of 3 - 4 x 10²⁴ J per year. According to some studies using the 2002 World's energy requirement figure, this absorbed energy figure represents more energy in one hour than the Earth need in one year!!.

With the brief facts presented below, it goes without saying that if properly harnessed, the sun's energy can be directly used to provide all the energy needed on Earth.

Literally, the sun powers the universe - everything on Earth derives its energy from the sun. Over years, the sun energy is converted into other energy sources such as fossil fuels, biomass, wind, hydropower etc which we have used extensively to meet the energy needs of our World. These are indirect energy sources and one of them particularly, fossil fuels (crude oil, gas and coal) have been used predominantly for energy supply to provide electricity for light and heat for domestic and industrial uses. Unfortunately, fossil fuels produce energy and produce with it considerable amount of pollutions and the greenhouse gases that endanger our environment. Moreover, fossil fuels are not renewable.

Solar Energy Applications:

Solar energy has been used for thousands of years to dry clothes and agricultural products, among other things. With the growing concerns over climate change and global warming and the need for alternative energy sources, there is increased consciousness of using solar for energy production for domestic and industrial uses. The current and potential uses to which solar power can be put are:

Electricity generation through solar power plants or photovoltaic systems
Space heating and cooling in active and passive solar buildings;
Natural lighting or "daylighting";
Solar Water Heating - to provide hot water for homes, businesses and swimming pools;
Thermal cooking;
Water treatment by "thermal" distillation and disinfection;
Providing high temperature process heat for industrial purposes;
Agricultural purposes (drying, power supply for equipment, running

greenhouses etc); and
Solar electrical vehicles.

The applications above can be discussed under two broad headings:

(i) Solar Electricity; and

(ii) Solar Heating

Please follow the links for each subject heading for further details.

Solar Energy and the Environment:

Solar energy is a renewable resource. A renewable resource is a resource that is able to be replaced or replenished, either by the earth's natural processes or by human action. Solar energy is available at varying proportions almost everywhere on earth. It cannot be depleted unlike the fossil fuel based energy resources.

Solar energy is a “clean” energy resource. It does not involve the emission of Green House Gases (GHGs) that are believed to be responsible for the worsening global warming of our planet, Earth. It provides a suitable energy alternative to the traditional fossil fuel energy sources that are currently widely in use.

The slight drawback for Solar Energy are waste products generated from the use of silicon to produce PVCs and possible desertification from operating solar thermal farms (expanse of land containing collectors or PVCs). These defects can however be managed effectively to limit impact on the environment.

Other Sources of Information: