Crystalline PV technology has the scope to reach grid parity faster and ensure green power production
Raghunandan SS, vice president, engineering, Kotak Urja Pvt Ltd
Tuesday, July 10, 2012: Crystalline photovoltaics (PV) technology has gained considerable market share. The silicon required for crystalline PV is obtained by secondary production of low purity silicon from the semiconductor processes of the electronics chip industry. Till the mid-90s, the semiconductor industry had surplus silicon of low purity levels and the PV industry could get easy access to it. With the rising global demand, the semiconductor industry could not generate enough raw material for crystalline PV, which led to the development of manufacturing lines for solar grade silicon. Even these lines could not meet the entire demand immediately. This opened up opportunities for other technologies like thin film and concentrated PV.
Competition from thin film technology
Thin film based photo voltaics was developed in the late 70s. However, its use was limited to calculators and digital clocks. The main limitation to exploring thin film on a large scale was its poor conversion efficiency and high capex costs. By 2006, the silicon shortages made crystalline module prices as high as US$ 4 per Wp, and the nanotechnology based thin film PV made a hurried re-entry into the market. At this time, thin film offered an attractive price of around US$ 2.5 per Wp. Against crystalline PV prices of over US$ 4 per Wp, thin film appeared very profitable. In spite of its poor conversion efficiencies and high capex, due to its lower price, thin film appeared set to wipe out crystalline PV from the market.
At this juncture, when thin film technology was hurriedly revived, people did not foresee the series of problems in manufacturing, lower efficiency, higher breakages, non-uniform product performances and the other realities of crystalline PV. A few investments made in thin film technology were written off in a very short time after being set up. The crystalline PV easily countered the price threat by reducing costs to match thin film prices. With very high capital investments involved in thin film PV, the price challenge by crystalline PV could not be easily battled out. This essentially required a technical approach by means of efficiency enhancement and lower cost of production. Due to the complexity of the nano technology approach, the increase in efficiency appeared to be a greater challenge.
By 2011, only one company from the US had bettered the efficiency to 11.8 per cent. The others, including the old players in thin film, could only reach a maximum efficiency of 9 per cent. The complex nanotechnology involves a greater challenge both in technology improvement and capex costs. For the thin film industry to better its efficiencies by even one per cent, it is estimated that at least four years of R&D would be required. Further, raw material availability must also improve in parallel to technological development.
Competition from concentrated PV
With field level efficiency of thin film and crystalline PV below the 20 per cent mark, there has been explorations of higher efficiencies in PV technologies. The concentrated PV (CPV) has been one such exploration. Even though CPV has appeared to cross the 20 per cent efficiency mark, there is a bigger challenge with regard to deploying the technology on a mass scale. Some of the limiting factors are the need for direct beam radiations and essentially tracking, which make this technology suitable only for limited geographies.
Crystalline PV regains supremacy
Crystalline PV has been steadily growing since the beginning, both in terms of technological developments and market acceptance. By the 90s, crystalline PV established itself as a technically proven solution, but it was a phase during which the industry did not prioritise on R&D too much. Till 2006, the price was on an upward trend. This was mainly due to the increasing market demand and insufficient supply of PV modules. However, the key contributor to the price was ‘polysilicon’.
Due to requirements for very high investments, high power, complex technological processes and exclusive use of raw materials, which were a by-product of the semiconductor industry, the production of polysilicon was only in the hands of seven companies across the world called the ‘seven sisters’ and they dictated the price trends for the industry. By 2006, the polysilicon market witnessed an artificially high price of US$ 450 per kg. However, the number of players in the polysilicon space increased and thin film’s re-entry made the polysilicon players adjust to competitive levels.
Even though the production of polysilicon is energy intensive, there are hardly any costs apart from the abundantly available raw material of quart silica in the earth’s crust. This means that the polysilicon production costs per kg could be well below US$ 20. However, crystalline technology offered greater scope for price reduction. This reality was not anticipated by those who promoted the re-entry of thin film technology. The aggressive R&D on the efficiencies of crystalline PV was also underestimated by the thin film industry.
Moreover, the production of polysilicon from new sources holds the promise of developing low cost silicon manufacturing processes, which will enable further price reduction. This is apart from what is available from the semiconductor chip industry. Besides this, the ingot growth and wafering processes have a major role in increasing wafer quality and in reducing prices.
Typically, any upgrade in technological innovation which, for instance, resulted in pitting electronic storage technology vs magnetic storage, or GSM mobiles vs pagers, etc, often resulted in the complete elimination of the earlier technologies. In all the cases, the newer technologies offered the benefits of utility and price. Such a comparison is not applicable in the case of thin film and crystalline PV. Thin film or concentrated PV today are just other methods of generating electricity with no big advantages over crystalline PV. They cannot completely eliminate crystalline PV but can help realise lower costs for crystalline PV, bringing it to grid parity levels, faster.
Crystalline PV has successfully passed the phase of establishing and proving itself for large scale deployment. Since 2000, the manufacturing process optimisation for higher efficiencies and volumes has improved. With the focus on grid parity, the cost reduction has begun by way of optimising the consumption of raw materials. An increase of just 1 per cent in efficiency would mean an increase in power by 25W/sq m of area leading to lower consumption of raw material and higher returns on investment. Crystalline PV has proved to be a more commercially viable manufacturing approach than any of the other current technologies. It has the scope to reach grid parity faster, while ensuring green power production.
Electronics Bazaar, South Asia’s No.1 Electronics B2B magazine
