Solar PV technology value chain in respect of new silicon feedstock materials: A context of India and its ambitious National Solar Mission

Achieving energy security through sustainable technologies is the most challenging objective that needs to be fulfilled within the context of rising energy demand in a country like India. Although nuclear energy is expected to meet a part of India's energy demand by 2030, this would still be non substantial and more importantly an unsafe way of producing power as demonstrated by a series of negative events that have marred its reputation as a sustainable technology, particularly in the wake of recent nuclear disaster at the Fukushima power plant in Japan. And with increasing pressure on every country to switch over from fossil-fuel based energy to clean and renewable energies, India has rightly announced its ambitious National Solar Mission (NSM) to install 20 GW of solar power by 2022 in Nov 2009. This paper discusses how India can achieve this target by adopting various solar PV technologies and processes. Until not so far back in time, poly-silicon (Si) production primarily catered to the semiconductor markets; however, the world now realizes that much silicon is required for the fast growing solar industry as well. The only Si production process that has dominated the world market has been the Siemens process, which is highly capital and energy intensive. Further this process is not carbon-neutral, since it uses coke and woodchips as reducing agents, causing considerable deforestation. Scientists and technologists across the world realize that spending so much money and energy to produce silicon can be avoided and have thereby begun to research on alternative technologies to produce silicon for the solar industry. As a result several new and disruptive technologies have emerged such as solar grade silicon (SoG) also known as UMG (Upgraded Metallurgical Grade) silicon, which involve substantially lesser resources in terms of capital & energy and are therefore carbon-neutral at the end of the day. Solar grade silicon of purity 99.9999% still dominates the PV industry across the world. In this paper, we give an account of UMG silicon methodology with the view that it has the potential to be a disruptive technology for existing high-purity solar grade silicon producers at the same time a revolution for the PV industry. For instance UMG-Si uses 1/3
^rd
the cost, 1/15
^th
the energy and 1/10
^th
capex (capital expenditure) of Siemens process. For many years to come Silicon (Si) solar cells will contribute significantly towards production of mono and multi crystalline PV modules. If India has to achieve the target, over and above set by the NSM then it must begin to focus on producing Si by adopting new processes that have been aforementioned. By doing so, India could emerge as a true world leader in solar PV, marching alongside countries like Germany who are determinedly working towards meeting a quarter of their energy requirements through solar technologies by 2050.