Solar energy is produced by the sun. It’s the energy transmitted from the sun in the form of electromagnetic radiation. It is taken from the sun and converted into electrical/ thermal energy. Solar is actually the Latin word for sun. There are many reasons why solar energy is better for the environment but there are some down sides. 
The earth receives about 1,366 watts of direct solar radiation per square meter. In one second the sun produces energy to meet the current needs of the entire Earth for 500,000 years. Solar energy used to photosynthesis. 99.99% of solar radiation goes to waste. Solar energy will never run out and it is very abundant and clean.
 Solar energy has been used by humans for thousands of years. For example, ancient cultures used energy from the sun to keep warm by starting fires with it. They also kept their homes warm through passive solar energy designs. Buildings were designed so that walls and floors collected solar heat during the day that was released at night to keep them warm. If you have ever stood in the sun to get warm then you too have utilized solar thermal energy.

 The discovery of photovoltaic happened in 1839 when the French physicist Edmond Becquerel first showed photovoltaic activity. Edmond had found that electrical current in certain materials could be increased when exposed to light. 66 years later, in 1905, we gained an understanding of Edmonds' work when the famous physicist Albert Einstein clearly described the photoelectric effect, the principle on which photovoltaic are based. In 1921 Einstein received the Nobel Prize for his theories on the photoelectric effect.

 Solar cells of practical use have been available since the mid 1950’s when AT&T Labs first developed 6% efficient silicon solar cells. By 1960 Hoffman Electronics increased commercial solar cell efficiencies to as much as 14% and today researchers have developed cells with more than 20% efficiencies. 20% efficient means that out of the total energy that hits the surface of a solar cell; about 20% is converted into usable electricity.

 The first long-term practical application of PV cells was in satellite systems. In 1958 the Vanguard I, was launched into space. It was the first orbiting vehicle to be powered by solar energy. Photovoltaic silicon solar cells provided the electrical power to the satellite until 1964 when the system was shut down. The solar power system was so successful that PV’s have been a part of world-wide satellite space programs ever since. The sun provides endless nonpolluting energy to the satellite power systems and demand for solar cells has risen as a result of the telecommunications revolution and need for satellites.

 The energy crisis and oil embargoes of the 1970’s made many nations aware of their dependency on controlled non-renewable energy sources and this fueled exploration of alternative energy sources. This included further research into renewable sources such as solar power, wind power and geothermal power.

 An economic breakthrough occurred in the 1970's when Dr. Elliot Berman was able to design a less expensive solar cell bringing the price down from $100 per watt to $20 per watt. This huge cost savings opened up a large number of applications that were not considered before because of high costs. These applications included railroads, lighthouses, off-shore oil rigs, buoys, and remote homes. For some countries and many applications, solar energy is now considered a primary energy source, not an alternative.


Down Sides to Solar Energy: 
 * Solar energy technologies still remain a costly alternative to the use of readily available fossil fuel technologies. As the price of solar panels decreases, we are likely to see an increase in the use of solar panels. 
 * Solar energy installation requires a large area for the system to be efficient in providing a source of electricity. This may be a disadvantage in areas where space is short, or expensive (such as inner cities).
 * Pollution can be a disadvantage to solar panels, as pollution can degrade the efficiency of photovoltaic cells. Clouds also provide the same effect, as they can reduce the energy of the sun’s rays. This certain disadvantage is more of an issue with older solar components, as newer designs integrate technologies to overcome the worst of these effects.
 * Solar energy is only useful when the sun is shining. During the night, your expensive solar equipment will be useless, however the use of solar battery chargers can help to reduce the effects of this disadvantage.
 * The location of solar panels can affect performance, due to possible obstructions from the surrounding buildings or landscape.Main Advantages of Solar Energy:

Main Advantages of Solar Energy:
 * Solar cells are long lasting sources of energy which can be used almost anywhere.
 * Solar cells provide cost effective solutions to energy problems in places where there is no mains electricity. Solar cells are also totally silent and non-polluting. As they have no moving parts they require little maintenance and have a long lifetime. Compared to other renewable sources they also possess many advantages; wind and water power rely on turbines which are noisy, expensive and liable to breaking down
 * Rooftop power is a good way of supplying energy to a growing community. More cells can be added to homes and businesses as the community grows so that energy generation is in line with demand. Many large scale systems currently end up over generating to ensure that everyone has enough. Solar cells can also be installed in a distributed fashion, i.e. they don't need large scale installations. Solar cells can easily be installed on roofs which mean no new space is needed and each user can quietly generate their own energy.