Silicon Wafer Photovoltaics
Hubert P. Seigneur, U.S. Photovoltaic Manufacturing Consortium (PVMC)
Abstract
The crystalline silicon (c-Si) program of the U.S. Photovoltaic Manufacturing Consortium (PVMC) performed a Pareto exercise with more than 30 separate organizations from industry, national labs, and academia to identify and prioritize the critical challenges for c-Si feedstock and wafering. An annual Pareto exercise such as this is not only a valuable tool to guide the identification and selection of potential consortium projects, but also an essential step towards achieving true consensus among its members. In addition to providing the results of this latest Pareto exercise, this article outlines the journey through the intricacies of this challenging yet exciting process.
This article has been restricted to registered FuturePV users. If you have an existing account, please log in. Otherwise, please register for a user account to view this article - REGISTRATION IS QUICK AND FREE.
Lang Zhou, School of Photovoltaics, Nanchang University
The apparently promising monocrystalline-like cast silicon has not yet reached its expected commercialization scale since its pilot in 2010. Two major technical challenges are identified: the need to obtain 100 percent monocrystalline wafers; and the hope of achieving higher cell efficiency by reducing dislocations in the cast monocrystalline silicon, which is found to consist of subgrains. A solution to meet the challenges is suggested.
This article has been restricted to registered FuturePV users. If you have an existing account, please log in. Otherwise, please register for a user account to view this article - REGISTRATION IS QUICK AND FREE.
Kristian Peter, CEO, ISC Konstanz
Crystalline silicon cells and modules
Over the last few years, crystalline silicon PV has deployed at a faster rate than previously expected. The result in these times is a tremendous production overcapacity, and companies are forced to sell PV products below production prices accordingly. New markets are therefore important and it is only a question of time until the demand for solar modules and systems again will increase.
N. Guillevin et al., ECN Solar Energy
The advantages of the MWT technology are large: Apart from the increase in cell and module efficiency, the module manufacturing can be done with higher yield, a higher degree of automation and a much smaller equipment footprint. Also, the MWT technology reduces stress from the interconnection process and thus allows thinner cells, offering additional cost-reduction possibilities. Advances in mainstream H-pattern cell equipment and technology, such as selective emitter technology, can easily be incorporated in MWT.
This article has been restricted to registered FuturePV users. If you have an existing account, please log in. Otherwise, please register for a user account to view this article - REGISTRATION IS QUICK AND FREE.
Stefan Glunz, Head, Department of Solar Cells − Development & Characterization, Fraunhofer ISE
The winds of change
The screen-printed Al-BSF silicon solar cell has dominated photovoltaic technology for the last 20 years. And indeed it is a great success story that this quite simple cell structure was boosted by plenty of evolutionary steps to remarkable cell efficiencies and excellent productivity. However, the potential for further increases in efficiency and cost reduction will soon saturate. Thus, a new generation of cell structures is just around the corner, and the winds of change aren’t caught in researchers’ labs anymore, but have reached the production lines. There are several hot topics for new cell structures such as optimized surface passivation, new metalization technologies, the use of n-type instead of p-type silicon and advanced cell structures that can be contacted only at the rear.
Cost Pressure in PV Systems Manufacturing
Extreme fluctuations in demand on the PV market challenge both PV system manufacturers and the supplier industry. Who can possibly keep up with the “killer cycles for the plant engineering industry,” as an industry professional recently phrased it. What is the recipe for success when it comes to surviving in the market? Last year, many companies tried to secure market share through large production capacity increases. Now, on top of declining federal PV subsidies around the world, excess capacity is placing additional cost pressure on companies. Numerous German companies are market leaders in plant engineering, and their systems are used to produce in China and other growing PV markets. How long will the “Made in Germany” factor still last, and what constitutes it anyway?
B. Herter, M. Peters, S. Janz, M. Hermle, J.C. Goldschmidt
Introduction
Photons below the band gap of a semiconductor solar cell are transmitted through the cell and therefore cannot contribute to current generation. For silicon solar cells, about 20 percent of the incident energy is lost. Upconversion of low-energy photons can reduce these losses. Thus, the theoretical efficiency limit of a silicon solar cell is increased from close to 30 percent[1] up to 40.2 percent.[2]
This article has been restricted to registered FuturePV users. If you have an existing account, please log in. Otherwise, please register for a user account to view this article - REGISTRATION IS QUICK AND FREE.
Els Parton, Robert Mertens, Jef Poortmans
The ITRS is the world-famous International Technology Roadmap for Semiconductors. It is the guideline for the semiconductor industry forecasting technology requirements. In the same way, roadmapping exercises have been performed for the PV industry. One example of such a roadmapping exercise is the ITRPV, the International Technology Roadmap for Photovoltaics. It predicts a decrease in module manufacturing cost per peak watt by a factor 2 to 3 over a period of 10 years (Figure 1). This of course assumes a sustainable market growth and progress in technology.
This article has been restricted to registered FuturePV users. If you have an existing account, please log in. Otherwise, please register for a user account to view this article - REGISTRATION IS QUICK AND FREE.
Robert David Vinje, VP of Expansions, SunPower Corporation
PV manufacturers are focused on two things: cost reduction and cell efficiency. There are many different approaches to optimizing these items individually, but technology and manufacturing advancements are tackling cost reduction and cell efficiency as two advantageously intertwined opportunities.
Mike Moore, Vice President, SVTC Solar
Depending on who I talk to, I hear two very different perceptions about innovation in the solar industry. Some people believe that solar manufacturing and technology has now stabilized and that there will be incremental technology improvements introduced into the marketplace while most of the improvements to drive us toward grid parity will come from the increased scale of factories and reduction in both balance of system and consumable costs. The other camp, which I will admit to being a member of, believes that there are still large opportunities for cost reduction and performance improvement in solar technology that will result from technical innovation (in addition to those incremental improvements described above). At the IEEE PV conference in June, Alan Goodrich, senior analyst for Solar PV Manufacturing Technologies at the National Renewable Energy Lab, presented a paper that included a crystalline silicon (cSi) cost roadmap. Dr. Goodrich’s roadmap clearly demonstrates the extraordinary opportunities that still exist through technological advances such as selective emitter, rear contact, and no kerf wafer manufacturing, which will combine with incremental improvements such as thinner wafers, advanced passivation schemes, different metalization approaches and the continued reduction in the price of consumables due to the scaling of the industry to continue reducing the costs of cSi modules.
