The sun’s energy is enormous and the earth receives about 3x1024 Joules of it per year in the form of electromagnetic radiation across a wide spectral range (mostly visible, near infrared and a small amount of ultraviolet). India, lying in the tropical belt, has an advantage of receiving this clean, renewable and sustainable solar energy for 300 to 330 days every year and can easily generate 5000 trillion kilowatt hours per year of solar energy. Thus, a blend of solar power coupled with efficient energy storage, currently achieved through photovoltaics (PV) is key to true energy dependence. India’s green energy revolution has enhanced her global stature in terms of meeting an escalating demand for energy, economic and environmental security. It is the most promising candidate to solve the energy crisis while opening umpteen employment opportunities and combating climate change. India stands fifth in the world in terms of solar power across its plants which currently account for 38% of its total renewable energy capacity. In 2015, India initiated the International Solar Alliance to reduce dependence on non-renewable sources of energy. Having accomplished the target of installing 20 GW solar power plants by 2022 through solar parks and rooftop solar panels, India set a new target of 100 GW solar power by 2022. In addition, three of the five top large solar parks in the worldwide are located in India. The world’s largest solar power plant is the Bhadla power plant, Rajasthan with a capacity of 2255 MW.
This article is an attempt to present the current status of solar cell technologies in India, the Challenges, opportunities and initiatives by the government to promote research in this field. It also gives a broad view of the emerging technologies in the solar sector that enable greater harnessing of the sun’s energy that India receives in abundance.
TYPES OF SOLAR TECHNOLOGIES
The Green energy revolution has brightened up hopes of sustainably addressing the growing demands of energy, economic and environmental security in India. Continuous depletion of fossil fuels over past decades have forced us to switch over to renewable sources. The pollution free, renewable and abundantly available solar energy stands as one of the most promising candidates to solve India’s future energy crisis. It can increase prosperity and open new employment opportunities for millions, ensuring energy security and combating climate change. The two main technologies which rule solar power innovations are Photovoltaics (PV) and concentrated photovoltaic systems. Photovoltaic (PV) cells convert solar energy into electrical energy by absorption of sunlight. Their origin dates back to 1839, credited to French physicist Edmond Becquerel. The First practical PV cell ie. a crystalline silicon solar cell with 6% efficiency was developed in 1954 at Bell Laboratories, USA. This was followed by a whole lot of research in converting sunlight into electricity particularly using polycrystalline silicon solar cells. These technologies are today widely used commercially and may be summarised as mentioned below.
- First generation polycrystalline silicon solar cells achieved conversion efficiency of 27% at lab level and 15-17% commercially.
- Second generation thin film solar cells of the 1970s had the advantage of low manufacturing cost were made by placing one or more thin films of copper indium gallium selenide (CIGS), cadmium telluride (CdTe) etc on substrates like glass, metal or plastic.
- The third generation solar cells have driven the development of novel PV material with low manufacturing cost and better efficiencies. These include multijunction or tandem cells which deliver highest efficiency upto 47% and allow absorbance of light in a broader range of wavelength, organic solar cells made of conductive organic polymers for light absorption that give power efficiency of approximately 18%, dye sensitised solar cells that have advantages in fabrication and are economical with efficiencies up to 14%; quantum dot sensitised solar cells that use quantum dots (light sensitive nanoparticles) as light absorbing material that deliver upto 16% efficiency and recently the most promising perovskite solar cells that use hybrid organic- inorganic lead or tin halide based material for light harvesting. Their high efficiency of about 22.1% make them very attractive in the PV community, generating power comparable to leading silicon solar cells with lower costs.
Concentrated photovoltaic systems convert sunlight energy into electrical energy in the same way that conventional PV does. The difference lies in the use of optical light collectors like lenses or mirrors that focus sunlight to a small area. Microgrids are power supply systems with an array of renewable energy sources and have reduced costs, increased reliability and improved environmental performance for communities. Apart from such traditional technologies some innovative technologies that have caught attention such as:
- Bifacial solar panels which produce power from both sides of a bifacial module enabling increased energy generation.
- Hairy solar panels that use light absorbing nanowires combined with carbon nanotube fabrics.
- Floating solar panels which allow PV panels to be installed on water bodies such as reservoirs, lakes, canals, irrigation etc.
- Solar energy harvesting trees in which flexible organic solar cells behave as leaves and generate, store solar energy.
- Bio solar cells where electricity is generated from microbial photosynthetic and respiratory activities.
The Ministry of new and renewable energy (MNRE) is the nodal agency responsible for research and development in renewable energy, to ensure energy security, increase the share of clean power, availability, access, affordability and energy equity. The MNRE launched The Jawaharlal Nehru National Solar Mission in 2010 to achieve 2000 MW of grid connected solar power by 2022 in three phases through several steps including Solar park scheme, central public sector undertakings (CPSUs) scheme for grid connected solar PV power projects, viability gap funding (VGF) and so on. Apart from this the Pradhan Mantri Urja Suraksha Uttan Mahabhiyan Yojana (PM-KUSUM) for grid connected agricultural solar pumps, Suryamitra skill development programme by the National Institute of Solar Energy (NISE), for Solar Energy project’s installation, operation & maintenance; National Wind – Solar hybrid policy, Atal Jyothi Yojana to provide solar street lighting systems for public use and Solar transfiguration of India (SRISTI) scheme for rooftop solar power projects are some government initiatives taken.
CHALLENGES AND OPPORTUNITIES
Innovation in solar technology provides more accessible energy efficient results and can help expand business. However, despite the efforts the challenges that India needs to tackle include:
- Dependency: Most Solar modules are still imported from China. India needs to be able to compete with China’s strong manufacturing base that gives stiff challenges to Indian domestic manufactures. This is essential to achieve self reliance in the solar sector.
- Waste Management: India’s solar waste is estimated to grow to 1.8 million tonnes by 2050. However, currently India’s e-waste rules do not mandate solar cell manufacturers to recycle or dispose of waste from this sector.
- Space Cringe: The lack of space to install large scale ground mount solar systems has been a challenge for many countries. This gives scope for greater R&D and innovation in terms of installation.
- Low tariffs: Solar tariffs are the lowest in India making them unsustainable for some developers and can lead to compromise in the quality of solar panels. There is a need to maintain viability issues both in terms of tariff and profitability.
- Financing mechanism: A critical issue is an absence of innovative financing options offering higher sums at lower interest and longer durations. A few steps taken in this regard include the National Clean Energy and Environment Fund, Green Masala Bonds etc.
- Solar irradiance: Fluctuation of solar radiation and temperature affects the power quality PV systems. High connection densities at the distribution grid and low irradiance can lead to undesirable variation of power supply quality and remains to be addressed.
- Balancing national priorities with International commitments: India’s domestic content requirement (DCR) clause faced legal challenges at the world trade organisation (WTO) and India needs to strike a fine balance between prioritising domestic goals and global goodwill.
With immense potential in the solar energy sector, India shall invest prudently in new and emerging solar technologies through strong financial measures that include green bonds, clean energy funds and institutional loans. There is a need to promote R&D particularly in renewable energy storage technology and tackle bureaucratic hurdles in implementation of such efforts. India must also take proactive steps towards formulation of an efficient Solar PV Waste Management and Manufacturing Standards Policy for sustainable waste management, in order to make it a truly green source of energy. India shall also leverage on the Ministry of External Affairs’s New and Emerging Strategic Technologies (NEST) Division to engage in technology diplomacy and negotiate technology governance to favour India. The setting up of the “Empowered Technology Group” is yet another step in the right direction to ensure sustainability of the technologies being developed that is essential to ensure ‘Atmanirbharta’ for the new India that we all aspire to live in.