Solar Cell-Process, Position and Bazaar

Solar cell or photovoltaic (PV) cell is a semiconductor material, which combines some properties of both metals and insulators making it uniquely capable of converting light into electricity. When light is absorbed by a semiconductor, photons of light can transfer their energy to electrons, allowing the electrons to flow through the material as electrical current. Single photovoltaic device, typically available in 12.5 cm and 15 cm square sizes, produces about 1-2 watts of power. To boost the power output of PV cells, they are connected together in chains to form larger units known as modules or panels. Modules can be used individually, or several can be connected to form arrays. PV modules are typically rated between 50W and 350W. One or more arrays are connected to the electrical grid as part of a complete PV system.

Types of Solar Cells

Monocrystalline

Monocrystalline silicon is the base material for silicon chips used in virtually all electronic equipment today. Mono-Si also serves as photovoltaic, light-absorbing material in the manufacture of solar cells. Monocrystalline panels have been commercially developed since the 1960’s. Monocrystalline panels have the best space efficiency and thus occupy lesser space. The cells in monocrystalline modules are cut from a single silicon crystal into wafers roughly 0.2mm thick which make them highly efficient.

Polycrystalline

Polycrystalline cells were previously thought to be inferior to Monocrystalline because they were comparatively less efficient. However, because of the cheaper method by which they can be produced coupled with only slightly lower efficiencies they have become the dominant technology on the residential solar panels market. Polycrystalline or multicrystalline panels have been in mass production since the late 1970’s. Polycrystalline modules are made from cells composed of multiple small silicon crystals which make them cheaper to produce though they are slightly less efficient than monocrystalline modules.

Thin-Film

A thin-film solar cell is a second generation solar cell made by depositing one or more thin layers, or thin film (TF) of photovoltaic material on a substrate, such as glass, plastic or metal. Thin-film solar cells are commercially used in several technologies, including cadmium telluride (CdTe), copper indium gallium diselenide (CIGS), and amorphous thin-film silicon (a-Si, TF-Si). The layers making up thin-film modules are about 40 times thinner than a strand of human hair, at just 2 microns. The layers can be deposited on glass forming a panel similar to crystalline modules, but many other materials can also be used and flexible panels can be made. Although these panels perform better in low light, they take more space than other panels.

Process of Solar PV Cell Manufacturing

The basic component of a solar cell is pure silicon, which is not pure in its natural state. Pure silicon is derived from such silicon dioxides as quartzite gravel (the purest silica) or crushed quartz. The resulting pure silicon is then doped (treated with) with phosphorous and boron to produce an excess of electrons and a deficiency of electrons respectively to make a semiconductor capable of conducting electricity. The silicon disks are shiny and require an anti-reflective coating, usually titanium dioxide. Solar cells are made from silicon boules, polycrystalline structures that have the atomic structure of a single crystal. The most commonly used process for creating the boule is called the Czochralski method. In this process, a seed crystal of silicon is dipped into melted polycrystalline silicon. As the seed crystal is withdrawn and rotated, a cylindrical ingot or “boule” of silicon is formed. The ingot withdrawn is unusually pure, because impurities tend to remain in the liquid. From the boule, silicon wafers are sliced one at a time using a circular saw whose inner diameter cuts into the rod, or many at once with a multiwire saw.

1. Loading- The wafers are loaded on the load cell line (LCL). They are then analysed through cameras to detect the geometry of the wafer and micro-cracks.

2. Etching- This process textures the surface of the wafer so that the sunlight gets reflected rather than trapped. Wafers are rinsed with a strong base then like potassium hydroxide followed by acids like nitric acid.

3. Doping- Layer of diluted phosphoric acid is applied on the wafer through the phosphorous mist. Phosphorus doping is responsible to form the P-N junction on the wafer.

4. Diffusion- Diffusion is usually performed with using a gas/paste dopant. Cells are introduced in the diffusion furnace/conveyor furnace with a common Phosphorus dopant (such as POCl3), to create the N junction.

5. PECVD- Anti-reflective coating is applied on the wafer through the Plasma Enhanced Chemical Vapour Deposition (PECVD) machine to minimise the reflection of the sunlight.

6. Co-firing- The PV cells go through the printing cycle in which pastes of silver and aluminium are applied to the back side of the cell while another silver composition is printed on the front to serve as the collector grid to help the flow of electrons.

7. Sorting- The cells are finally sorted based on efficiency, colour, voltage/current into various categories.

Status

As per the National Solar Mission targets, indigenous manufacturing capacity to the tune of 4-5 GW is to be achieved by the year 2020 in India. According to the Ministry of New and Renewable Energy (MNRE) data released in 2016 India’s current manufacturing capacity of solar cells and modules in the country is 1,468 MW (operational 1,123 MW) and 5,648 MW (operational 4,307 MW), respectively. The data shows that till June 2016, India had 20 companies actively involved in solar cell production and as many as 94 companies are manufacturing solar PV modules in the country. Out of 20 solar cell companies, three companies – Jupiter Solar, Indosolar and Moser Baer Solar – represent 780 MW, or over 53%, of the total installed production capacity.

The cell manufacturing capacity in India increased from 1,216 MW in June 2014 to 1,468 MW in June 2016. Capacity utilization in June 2014 was merely 20% which has increased to 76.5% in June 2016. Capacity utilization in solar module manufacturers is also high at around 74%. A total of 94 companies have a cumulative installed production capacity of 6,848 MW solar PV modules per year, of this 4,308 MW capacity is being utilized. Vikram Solar (500 MW), Waaree Energies (500 MW) and Tata Power Solar Systems (300 MW) are the three largest manufacturers of solar PV modules in India representing 23% of the installed capacity; all three also reported 100% utilization of their production capacity.

Growth in the solar PV module manufacturing capacity has been much greater than that in the solar cell manufacturing sector. The capacity utilization has also gone up from 28% to around 74%. Solar sector in the country is in the middle of exceptional growth, fed by rapidly declining tariffs, improved technology and a global oversupply of photovoltaic (PV) cells and panels and other material, mainly from China.

Import and Export

Indian solar market in financial year (FY) 2016-17 from April to October, registered export and import activity totaling $1.22 billion (Rs.83.22 billion). This was $1 billion (Rs.68.35 billion) more compared to import and export activity worth $224 million (Rs.15.28 billion) in the same period in 2015 says Mercom Capital in its report. During the above mentioned period the country exported solar modules and cells worth $56 million (Rs.3.82 billion) and imported solar modules and cells worth $1.17 billion (Rs.79.81 billion). Compared to the same period in 2015, solar imports have grown by 40 percent, whereas exports have declined by 22 percent, down from the $72 million (Rs.4.91 billion) in the same period in 2015 says the report.

In the month of October solar imports grew by 10 percent and exports dropped by 84 percent in comparison to same month in 2015. China is the largest exporter of solar modules and cells to India, accounting for $1,023 million (Rs.69.78 billion) worth of India’s total solar import and an 87 percent market share, followed by Malaysia which accounts for $82.03 million (Rs.5.59 billion) of India’s imports and a 7 percent market share.

Solar Market Analysis

According to a report Indian solar market will witness a stellar growth in 2017 with total installed capacity reaching around 18 GW by the end of the year.

Bridge to India states that combined with 1.1 GW of expected rooftop solar capacity, India should add a total of 8.8 GW in 2017, ranking it amongst the top three global markets after China and the USA. Solar tariffs are expected to fall below the critical Rs. 4.00 (USD 0.06)/ kWh mark making solar power the cheapest new source of power. At the same time, improving financial health of power distribution companies due to UDAY implementation will also help in sustaining renewable energy demand in particular. The firm expects sustainable demand of 6-8 GW for utility scale solar in the coming years.

On the other hand, Mercom Capital expects solar installations in India to be over 9 GW in 2017, which would put the Indian solar sector in the big leagues along with China, the United States, and Japan.

Technological Advances

Last year in December, 1366 Technologies with Hanwha Q CELLS claimed that it has achieved a new performance record of 19.6% cell efficiency for 1366’s Direct Wafer technology. The result was independently confirmed by the Fraunhofer ISE CalLab and clearly demonstrates the combined potential of the two inventions – 1366’s kerfless, drop-in 156 mm multicrystalline wafers and Hanwha Q CELLS Q.ANTUM, passivated emitter rear contact (PERC) cell process. The wafers were produced with 1366’s current production furnaces in Bedford, MA and the cell fabrication was completed at Hanwha Q CELLS’ Center for Technology Innovation and Quality in Thalheim, Germany. In the same month, Trina Solar announced that it’s State Key Laboratory of PV Science and Technology of China has set a new world conversion efficiency record of 22.61% for a high-efficiency p-type mono-crystalline silicon (c-Si) solar cell. The solar cell was fabricated on a large-sized boron-doped Cz-Si substrate with a low-cost industrial process of advanced PERC (Passivated Emitter and Rear Cell) technology that integrates back surface passivation, front surface advanced passivation and antiLID (Light Induced Degradation) technologies. The 243.23 cm2 solar cell reached a total-area efficiency of 22.61%. This result has been independently confirmed by the Fraunhofer ISE CalLab in Germany. Trina Solar achieved a world conversion efficiency record of 21.40% for a large-area PERC mono-crystalline p-type solar cell in 2014, and the Company subsequently beat this with a 22.13% efficiency record in 2015. In July 2016, Trina Solar announced that its production lines were able to produce the same type of PERC solar cells in large volume with an average efficiency of 21.12%, which is only 1 percentage point less than the record efficiency that was achieved in 2015. Now Trina Solar has broken its previous efficiency record by about a half percentage point, reaching the highest efficiency level to date for a PERC cell fabricated with a low-cost industrial process on a large-area p-type mono-crystalline substrate.

Why India is Lagging Behind

Solar manufacturing includes mainly four stages – manufacturing of basic material for solar cells, whether monocrystalline or polycrystalline; cutting it up into wafers; making solar cells using the wafers and finally making solar panels and modules using the cells. Interestingly, the first two stages are not carried out in the country – most of the local players in solar industry import solar wafers.

It makes little sense for the local developers in the country to buy homegrown products, as the imported one are not only comparatively cheaper, but also technologically advance. With 17 per cent export benefit provided by Chinese Government to its solar manufacturers it makes nearly-impossible for the Indian companies to compete with them. Countries like US and EU has already imposed an anti-dumping duty on Chinese solar products, but India has so far avoided doing so, as that would sharply increase the cost of solar cells and panels and that in turn would hamper the solar dream. India removed anti-dumping duty on solar panels in September 2014. The solar auction process that India initiated, has witnessed steep drop in solar tariffs from Rs 6.93 per kilowatt hour (KWH) to less than Rs 4 per KWH by the end of 2016. Meanwhile, prices of solar panels have also tumbled because of improving efficiency.

Gyanesh Chaudhary, MD & CEO, Vikram Solar recently on a networking site said a strong domestic manufacturing eco-system is imperative to push a nation through socio-economic growth barriers. The Government of India needs to revisit and revive the investigation on imported solar modules from foreign countries. Normalization of import prices will help domestic manufacturers to gain significant advantages while ensuring a fair playing field, while boosting the Make in India programme at the same time. Chaudhary added domestic manufacturing can make India the third largest economy in the world by improving social, industrial, and economic infrastructure. From creating jobs to reducing import expenses, domestic manufacturing comes with an array of benefits that can boost national uplift. Research reveals that focusing on domestic manufacturing can save India more than $42 billion by 2030, which otherwise would be wasted on imports.

Domestic solar growth has already created more than 416000 new jobs (2015) including high-skilled manufacturing, indicating a solution for India’s employment scarcity. Taking a more aggressive initiative towards enhancing the domestic solar manufacturing capacity can also help in meeting the solar energy implementation target (100GW) and prepare India for the mantle of solar superpower said Chaudhary.

Beside Chaudhary many Indian manufacturers have already expressed their despondency on the auction process and nonimplementation of anti-dumping law. According to the manufacturers gradually falling prices are squeezing their margins and inhibiting them from investing in R&D because of which they are unable to bring new technologies and bring down the cost.

In an e-mail interaction with Saur Energy, Gyanesh Chaudhary expressed that the Government should completely lift excise duties with regards to machinery, equipment, spare parts etc deployed in a regular factory set up, meant for solar energy production projects. Additionally, he asserted full exemption from excise for raw materials required for manufacturing solar modules such as, tempered glass, back sheet, EVA Sheet, solar cells, flat copper wire which are needed for making PV Ribbons etc. The same should be applicable for GST.

Government should also look at exempting import duties on components and equipment that are required for establishing solar power plants, with the roll out of GST, he added.

To promote the indigenous solar industry, the Government should introduce more and more incentive schemes and overall reforms. The “Technology Up-gradation Fund”, like in the textiles industry should be introduced in the solar sector as well. The Government should also provide interest subsidies for the solar industry, said Chaudhary. He further added, favorable policy reforms will not only catapult the Government’s Make in India program but also will be a step towards realizing the Government’s target of electrifying the whole of India by 2020.

Lack of proper policies to improve local solar manufacturing, lack of technological advancement, cost and uncontrollable invasion of cheap solar imports are some of the factors that the nation is lagging behind. However, MNRE and Niti Aayog is formulating a new solar manufacturing policy which will harp on integrated manufacturing, where all the four processes of solar are carried out by manufacturers in-house.