By G V Joshi
One of the first major Solar Power related decision approved by the Union cabinet, is to develop 50 solar cities in India. This can give a major boost to the generation of solar energy and its use. The Indian city of Agra, former capital of the Indian in Mughal days and home of the Taj Mahal, is to become the country’s first solar city. Each state will have at least one solar city and this gives the project a national vision.
The cities are to be divided into different categories, and the aim is to reduce the demand for conventional energy in these by 10 per cent when the solar project gets implemented. Solar cities are being developed in many other countries and some of them have shifted to the use of solar energy in a major way.
The development of solar cities is a part of the government’s ambitious plan under the Jawaharlal Nehru National Solar Mission to increase the solar power generation in India.
All these days, solar energy was considered to be costly and was not competitive against conventional energy. But the situation has been changing since then. New technologies have brought down the cost of solar energy, which is now not much higher than that of thermal energy.
But a solar city will need a solar park nearby. What is a Solar Park? A Solar Park, also known as a photovoltaic power station in an engineer’s vocabulary, is a large-scale photovoltaic system (PV) designed for the supply of electricity into the main electricity grid from thermal/hydro/ nuclear power stations. They are sometimes also referred to as solar farms especially when sited in agricultural areas.
The Solar Park uses photovoltaic effect, which for a common man means producing electricity in a material upon exposure to any light but generally light from our Sun.
The photovoltaic effect was first observed by French physicist A E Becquerel in 1839. A photovoltaic cell or solar cell is an electrical device that converts the energy of light directly into electricity. Solar cells are the building blocks of photovoltaic modules, otherwise known as solar panels.
In 1883 Charles Fritts built the first solar cell by coating the selenium with a thin layer of gold to form the junctions; the device was only around 1 per cent efficient.
The first practical photovoltaic cell was publicly demonstrated on April 25, 1954 at Bell Laboratories, research wing of American Telegraph and Telephone Company (AT&T). The inventors were Daryl Chapin, Calvin Souther Fuller and Gerald Pearson. It was only six per cent efficient. Since then efficiency has been going up steadily. By 1960 the efficiency had reached 10 per cent. By 1985 the figure had crossed 20 per cent.
What is solar cell efficiency? Solar cell efficiency is the ratio of the electrical output of a solar cell to the incident energy in the form of sunlight. It is the percentage of the solar energy to which the cell is exposed that is converted into electrical energy.
Efficiency continued to go up and the prices continued to drop. The price of solar panels fell steadily for the next 40 years.
In September 2013, a solar cell achieved a new laboratory record with 44.7 percent efficiency, as demonstrated by the German Fraunhofer Institute for Solar Energy Systems.
A team from the University of New South Wales in Australia has achieved a record 40.4 per cent conversion efficiency by using standard solar cells combined with a mirror and filters. But these are achieved in research laboratories only. Solar cell energy conversion efficiencies for commercially available solar cells are only around 14-19%.
The first 1 MW solar parks was built by Arco Solar at Lugo near Hesperia, California, USA at the end of 1982. It was followed in 1984 by a 5.2 MW installation in Carrizo Plain also in California. Both have since been decommissioned, though Carrizo Plain is the site for several large plants now being constructed or planned.
Solar parks generally use unusable barren land. Those are the lands that are not used for agriculture and located away from cities. The idea of setting up large scale solar power plants in the wastelands of various parts of the country was first put in motion in November 2013 by the previous government.
India’s first Solar Park came up at Charanka village in Gujarat in April 2012. Spread over close to 5,500 acres of unused land in the District of Patan in Gujarat, “Charanka Solar Park” was developed by Gujarat Power Corporation Ltd (GPCL) under the state government’s solar policy.
The estimated capacity of the plans is 590 MW, and according to GPCL, a total of 224 MW has so far been commissioned by 20 developers.
Most of the projects were commissioned during the first half of 2012. In addition the park also has the capacity to generate 100 MW of Wind Power and is considered a good model for solar-wind hybrid Park.
The Dhirubhai Ambani Solar Park at Dhursar village near Pokhran in the Jaisalmet district of Rajasthan is one of a large number of solar parks expected to be built in a 35,000 km2 area of the Thar Desert that has been reserved for solar power projects.
The solar park was named after the late Dhirubhai Ambani, the founder of Reliance Industries, and was constructed using 500,000 modules by First Solar, and covers an area of 140 hectares.
India has a target of developing 22,000 MW of solar power plants, and an additional 8,000 MW is expected in local generation, bringing the total to 30,000 MW by 2022. There are about fifteen solar cell manufacturers in India. They can manufacture solar panels producing about 1,400 megawatts of electricity per year.
More than 85 per cent of the solar cells used today are made from crystalline silicon, but scientific research continues so find new materials that could do the job better.
Research on discovering new materials and achieving higher efficiency is going on throughout the world. There’s a lot of excitement about a class of materials called perovskites that promise to deliver efficient and cheap solar cells. There are predictions that the efficiencies could reach 50 per cent, and the costs could fall.
It is time scientists working at the National Physical Laboratory (NPL) at Delhi and other associated laboratory take up research on developing cheap and more efficient solar cells on a war footing.