- Solar Energy is the energy derived from Sun's heat or light. Solar energy is used to heat, cool or light homes and power businesses.

Some Facts about the Sun:

Sun is the central and the largest part of the solar system, making up about 99.8% of the entire system. Some of the basic characteristics of the Sun are:

• Mass: - About 330,000 times the mass of the planet Earth
• Shape:- Sphere with diameter of about 1.5 x 106 Km.
• Distance:-  About 1.5 x 108 Km away from the Earth
• Surface Temperature:- About 6,000oC,
• Temperature of the core:- About 1.4 x 107oC.
• Temperature of the Sunspots*: - About 4,000oC
• Luminosity**:- about 3.9 x 1026 Watts
• Solar radiaton to the Earth:- 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 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 in the form of heat and light.
• This absorbed energy figure represents more energy in one hour than the Earth needs in one year (according to some studies using the 2002 World's energy requirement figure). 
• Literally, the sun powers the universe - everything on Earth derives its energy from the sun. The energy from the sun is the one that gets converted into other energy sources such as fossil fuels, biomass, wind, hydropower and others. While energy from the sun can be called DIRECT Energy source, energy form these other sources could be called INDIRECT Energy sources.

*Sunspots are the the coolest regions of the Sun's surface

**Luminosity is the amount of energy emitted by a star each second - Sun is a star in the middle of the solar system.

What are Solar Energy Systems?

Solar Energy Systems are technologies that harness the heat and light, released from the Sun and absorbed into the Earth, to provide energy used in several forms - heating, lighting, cooling, power generation and so on, on earth. These technologies are in two categories - Solar Photovoltaic and Solar Heat

Solar Energy Applications:

The current and potential uses of solar energy are for heating, cooking and lighting which include but are not limited to the following:

• 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 purification or treatment by "thermal" distillation and disinfection;
• Generation of high temperature process heat for industrial purposes;
• Agricultural purposes (drying, power supply for equipment, running greenhouses etc); and
• Solar electrical vehicles.

Solar Energy and the Environment:

Some of the advantages of Solar energy over other energy sourcesare:

• 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 esponsible 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 drawbacks 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.

Related information on EB:

Photovoltaic Cells

Solar Heating

Solar Electricity

Daylighting

Other Sources of Information:

• Solar Energy - Energy from the Sun
• EIA Energy Kids - Solar