World's Largest Coal Maker Will Produce Solar Panels In India | What are Solar Wafers? | Solar wafer manufacturing process |

The world’s largest coal mining firm is to bellicosely go after solar energy and continue to close smaller mines.

 Solar power was considered a marginal power source, But it is now one of the major drivers behind the transition to greener, more sustainable sustainable energy.

India currently uses about one billion tons of coal annually, making it the world's second largest consumer behind China.

 Coal India Ltd, world's largest coal miner, would travel into solar wafer manufacturing and wants to aggressively participate in the country's solar energy auctions, its chairman told Reuters on Tuesday. Pramod Agarwal said its joint travel with state-run NLC India Ltd plans to invest around ₹ 125,000 crore in solar power projects with a capacity of 3,000 megawatts, in which Coal India will invest some ₹ 60,000 crore by March 2024. It plans to keep closing small mines and stay away from opening those that would require mass hiring.

Agarwal said that the company's regular falling headcount could lead to a major decrement in costs. The net decrement of employees is to the tune of 13,000 to 14,000 per annum. State-run Coal India will face increased costs due to periodical wage revisions for non-executive employees, effective from July 1, 2021. "But manpower reduction will have a stabilizing effect, so the wage bill effect may be flat, Agarwal said.

 Coal India also revealed that the company is going to shut down small mines while also abstaining from opening mines that would require mass hiring. He also stated that in a span of three years until March 2020, it has shut down 82 mines while also blistering its workforce by 18,600.

The report also mention that India as of now only makes solar cells, not wafers. To uplift the manufacturing of solar equipment in India, authorities are planning on imposing custom duties on some equipment starting in April 2022. 

Alongside the rise of solar, other clean energy sources like wind farms and hydropower are also growing. Renewable energy now generates a third of global power capacity.

What are Solar Wafers?

Silicon Wafer is a circular disk of high purity silicon material. It's a fundamental of photovoltaic power generation, and production foe which it requires high technology. Photovoltaic power generation system converts sunlight energy directly into electrical energy.

It is a form of photoelectric cell, defined as a device whose electrical characteristics, such as current, voltage, or resistance, vary when exposed to light. Individual solar cell devices are often the electrical building blocks of photovoltaic modules, known colloquially as solar panels. The common single junction silicon solar cell can produce a maximum open-circuit voltage of approximately 0.5 to 0.6 volts.

Solar wafer manufacturing process

The manufacturing and production process of solar cells from a single crystal p-type silicon wafer has different patents and company trade processes, however, the steps below are the generalized method and process of most number of Silicon/Solar Wafer manufacturers. 

1. Texturing - After the initial cleaning procedures, the wafer is being textured to create pyramid-like structures on the silicon surface. These pyramid-like structures made the incoming sunlight to reflect and bounce into other pyramids on the surface to improve the overall rate of sunlight absorption. 
2. N doping (usually Phosphorous) - After texturing, a variety of methods are being utilized to dope the top surface of the p-type solar wafer to produce n-type regions. This process typically uses gas diffusion in a high-heat furnace, can create a critical p-n junction which will form as the permanent electrical grid.  

1. Edge diffusion cleaning - The process of doping the surface of the solar wafer, causes the Phosphorous dopant to disperse to the wafer edges, and if the excess dopant remained it can cause short-circuits between the negative and positive contacts of the solar cell. So the excess dopant should be removed by an acid-etching procedure.
2. Anti-reflective coating - To improve its light absorption, the wafer will be coated by an anti-reflective coating which is usually a silicon nitride coating. 
3. Screen printing of front and rear surface contacts - This is the final step of the production process, the front, and rear surface contacts are being screen printed into the wafer surface to produce positive and negative contacts of the solar cell. Then, the solar cells are now ready to be wired altogether to make solar panels.

Top five largest solar power plants in India

1. Bhadla Solar Park – 2,250MW

Bhadla Solar Park is claimed to be the largest solar power plant in the world, it is located in Bhadla village, in Rajasthan’s Jodhpur district. crossing 14,000 acres, the fully operational power plant that has been installed with a capacity of nearly 2,250 megawatts (MW).

This huge solar power plant was developed by multiple entities, such as Rajasthan Solar Park Development Company Limited (subsidiary of Rajasthan Renewable Energy Corporation Limited), Saurya Urja Company, and Adani Renewable Energy Park Rajasthan (joint venture between Adani Enterprises subsidiary Adani Renewable Energy Park and government of Rajasthan). Rajasthan’s current solar power consumption is 10% of the state’s total power usage.

2. Shakti Sthala solar power project – 2,050MW

Shakti Sthala Solar Power, also known as Pavagada solar park, is a 2GW solar complex developed in Pavagada, Tumkur district, approximately 180km from Bengaluru, Karnataka, India.  The developers increased the capacity by 50MW.

The project was developed by Karnataka Solar Power Development Corporation Limited (KSPDCL), a joint venture between Solar Energy Corporation of India (SECI) and Karnataka Renewable Energy Development Limited (KREDL), with an estimated investment of Rs16.5bn ($2.5bn).

3. Ultra Mega Solar Park – 1,000MW

Kurnool Ultra Mega Solar Park is a solar park spread over a total area of 24 square km in Panyam mandal of Kurnool district, Andhra Pradesh, with a capacity of 1000 MW. It was inaugurated by then chief minister of Andhra Pradesh Nara Chandrababu Naidu on 8 Jan 2019. The park was built at an investment of around ₹70 billion (US$980 million) by solar power developers and the Central and State governments. Solar power developers invested ₹10 billion (US$140 million), while the remaining ₹60 billion (US$840 million) was funded by APSPCL supported by a ₹2 billion (US$28 million) grant from the Union Government.

4. Rewa Solar Power Project – 750MW

The 750- megawatt Rewa solar Power Plant in Madhya Pradesh was dedicated to the nation by Prime Minister Narendra Modi on Friday (July 10). The solar plant was set up by the Rewa Ultra Mega Solar Limited, a joint venture between Madhya Pradesh Urja Vikas Nigam Limited and the Centre’s Solar Energy Corporation of India (SECI). The project has also received Rs 138 crore financial assistance from the central government.

5. Kamuthi solar power plant – 648MW

Kamuthi Solar Power Project is a photovoltaic power station spread over an area of 2,500 acres (10 km²) in Kamuthi, Ramanathapuram district, 90 km from Madurai, in the state of Tamil Nadu, India. The project was commissioned by Adani Power. With a generating capacity of 648 MW_p at a single location, it is the world's 12th largest solar park based on capacity.