Solar energy has different solar technologies. It can be converted to electricity or heat in two ways:
Photovoltaic - the word “photovoltaic” is a combination of the words ‘photo’, which means light, and ‘voltaic’, which refers to the production of electricity. Photovoltaic technology generates electricity directly from sunlight (energy). A number of solar cells electrically connected to one another and mounted in a frame is called a photovoltaic module.
Individual cells can vary in size from about 0.5 inches to about 4 inches across. However, one cell only produces 1 or 2 watts, which isn't enough power for most uses. For solar electricity at home, solar cells are grouped together on rooftops.
A photovoltaic cell is a specially treated wafer of silicon, sandwiched between two thin contact plates. The top contact is positively charged and the back contact is negatively charged, making it a semiconductor. That semiconductor absorbs photons of light and release electrons. When free electrons are captured, an electric current results that can be used as electricity.
Photovoltaics is a very rapidly growing global technology. Homeowners, businesses, governments, local bodies, and non-profit organisations throughout the world use Photovoltaic (PV) panels to provide electricity for their needs. Users are found in rural, suburban and urban areas.
Solar thermal - at the core of a solar thermal system is the solar collector fitted at an optimal angle on a roof. It transforms the sunlight into heated fluid contained in it to very high temperatures. This fluid is then transferred via the pipes to the storage tank and stored there. There are also collectors which directly heat the air. Those systems circulate the air through collectors and transfer large part of energy onto the air. Later, that air returns itself to a heated chamber maintaining the chamber's temperature.
The most common types of solar water heaters are evacuated tube collectors (44%) and glazed flat plate collectors (34%) generally used for domestic hot water and unglazed plastic collectors (21%) used mainly to heat swimming pools.
Where to use solar systems?
A fundamental factor which determines availability of solar radiation is the climate formed by geographical factors, such as: latitude, size of lands and seas, sea tides, height above sea level, land formation. In order to determine opportunities of using solar radiation energy, the following fundamental parameters should be defined along with their distribution in time: insolation (number of hours of sunshine), irradiation of horizontal and sloped surface, structure of solar radiation.
The direct sun power incident on a solar panel depends not only on the power contained in the sunlight, but also on the angle between the solar panel and the sun. The tilt angle has a major impact on the solar radiation incident on a surface. For a fixed tilt angle, the maximum power over the course of a year is obtained when the tilt angle is equal to the latitude of the location. However, steeper tilt angles are optimized for large winter loads, while lower title angles use a greater fraction of light in the summer. .
Why use solar systems
Solar energy can be utilized for varied applications:
- Residential purpose - for heating the water with the help of solar heater. The PV can be installed on the roof of the residential home to collect the solar energy which is then used to warm the water. Solar energy can also be used in producing the electricity. Batteries will store energy captured in day time and supply power in night.
- Commercial and industrial purpose - is frequently used to power the radio and TV stations. It is also used to supply power to lighthouse and warning light for aircraft. The solar energy is also used in major industries for providing power for manufacturing process.
- Remote applications - off-grid locations can be also supplied with the solar energy.
- Transportation - Solar energy is also used for public transportation such as trolleys, buses and light-rails.
- Solar pool heating - The most popular domestic use of solar energy is the solar pool heating, this allows swimming even during cold seasons.
- The main advantages of solar energy are that it is clean, able to operate independently or in conjunction with traditional energy sources, and is remarkably renewable.
- FACTS - For a typical small farm, an array rated at about 1 kilowatt would provide sufficient energy to meet the basic electrical needs of a family of four – to power lights, television, radio, a small refrigerator and a microwave oven.
What are potential obstacles?
One of the main obstacles is the initial cost of the equipment used to harness the suns energy. Solar energy technologies still remain a costly alternative to the use of readily available fossil fuel technologies. A solar energy installation requires a large area for the system to be efficient in providing a source of electricity. Solar energy is useful when the sun is shining, the availability of solar radiation varies from day to day, and from season to season.