Solar energy is a renewable source of energy unlike other sources of energy such as petrol, natural gas, etc. Thus, harnessing solar energy not only meets the energy requirements for generating electricity or heating without causing pressure on non-renewable sources of energy but also provides a source of clean energy. The solar power energy is harnessed by photovoltaic solar technology. This technology utilises the phenomenon of photoelectric effect by which light is converted into electricity.
What are solar cells?
Solar cells or photovoltaic cells are small individual units made of different semi-conductor materials. Most common semi-conductor materials used to construct solar cells are Silicon and Selenium. Other semi-conductor materials used are cadmium, gallium, arsenide and indium.
When sunlight made of particles called photons strike the solar cell, the electrons on the outermost orbit of the atoms become energised and leave the atom. The resulting free electrons generate a current. This is known as photoelectric effect.
The voltage across the terminals of a solar cell is about 0.8V and the current produced is about 0.6A. The voltage produced by a PV cell depends upon the intensity of the incident solar rays.
What are solar panels?
A single solar cell produces juts 1-2 watts of power. Thus, in order to get more power, individual solar cells are connected together to form large units known as solar power panels or modules.
Solar cells can be connected in the following ways.
Series connection- In this setup, the current generated by each cell remains the same but the input voltage doubles.
Parallel connection-In parallel connection, the current generated by each cell doubles but the input voltage is unchanged.
Series+Parallel connection- In this type of connection, the magnitude of both the voltage and current generated by each cell increases.
Solar panels are constructed by connecting solar cells in Series+Parallel connection. Depending upon the type of solar cells used, the solar panels can be monocrystalline, polycrystalline, thin film or concentrated solar panels.
A solar panel has a front glass sheet which protects the solar cells against weather and debris. High strength tempered glass sheet of 3mm-4mm thickness is used. The solar cells are covered by a transparent film of ethylene vinyl acetate or EVA. EVA layer protects the cells against external impacts and moisture. The rear section of the solar panel is called backsheet. Backsheet is made of various types of plastic such as PET, PP and PVF. Backsheet provides protection against UV rays of the sun, moisture and impacts. It also provides electrical insulation. Aluminium frame protects the edge of the unit consisting of the solar cells. The frame protects the solar cells against strong winds and external impacts. It also serves as a platform for mounting the panel.
What is a solar power plant?
Solar panels can be connected with each other to form arrays. A solar energypower plant consists of large number of arrays of solar panels connected to an electric grid. Both small solar power plant and large scale solar power plants can be built according to energy requirements.
The largest solar panel power plant of the world is Tengger Desert Solar Park in China. The solar plant covers an area of 1200 km in Tengger Desert located in Inner Mongolia Autonomous Region and has an installed capacity of 1547MW.
There are many companies offering solar power plant for home. The area available on the roof of the house, energy requirements and other factors decide the type of solar panels to be installed. 74Wp to 100Wp solar panels are used for medium to large houses. 250Wp to 300Wp are the standard solar panels used in making solar power plants for very large houses. Wp stands for Watt Peak.
Solar power in India
India has made big strides in solar technology. There are many solar energy power plants in india located in various states of the country.
The solar power plants in india produce a total of 12,889 megawatt of energy. More and more solar plants are being installed in the country. It is estimated that by year 2030, India will fulfill 80% of its energy requirement by solar energy.
Bhadlia Solar Park is the top power plant in india in terms of solar energy. It is spread over an area of 10,000 acres near Jodhpur in Rajasthan and has a capacity of 2225 MW.