15 July 2010


SAFC Hitech outlines strategy to address solar industry

At this week’s Intersolar event in San Francisco, CA, USA, chemical manufacturer SAFC Hitech of St Louis, MO, USA (a business segment of SAFC within the Sigma-Aldrich Group) announced details of areas and initiatives on which it is working in the solar industry, as the drive to encourage the mass-market adoption of solar power gathers momentum.

As a global supplier of materials and solutions to the research and fabrication community focusing on PV cells, SAFC Hitech’s product portfolio includes materials used as dopants in the manufacture of crystal silicon cells and window layers in cadmium telluride (CdTe) and copper indium gallium (di)selenide (CIGS) photovoltaic cells. With the solar market expected to grow exponentially over the next decade (to at least 125GW in 2020), SAFC Hitech says that it is focusing on helping to address the historic barriers to the mass market adoption of solar energy, i.e. the energy conversion efficiency of cells and the high cost of solar systems. Looking ahead to future iterations of solar cell technology, the firm is working closely with customers and research partners to develop new specialty chemicals to enable the fabrication of next-generation solar cells.

“Although solar cells have been around for over 50 years, their efficiencies have only increased marginally in that timeframe, which has been a significant barrier to the wide-scale adoption of solar power,” says SAFC Hitech’s president Philip Rose.

As far back as 1957, Hoffman Electronics achieved 8% efficiency, a figure that rose to 14% in 1960. In 1992, the University of South Florida developed a CdTe thin-film photovoltaic cell that was 15.9% efficient. As recently as 24 June, SunPower Corp set a new record for large-area silicon solar cells of 24.2%. Essentially, it has taken over half a century for efficiency to treble.

Also, with domestic systems and installation costing about $20,000 or more, adoption of solar energy for many consumers means seeking Government or State incentives, or home equity loans. The US government recently set aside $150m to assist homeowners with the installation of solar panels and other energy improvements. However, this tax-assessed financing initiative — i.e. property assessed clean energy (PACE) loans, paid back over time by homeowners as an addition to their property taxes — has run into problems. The two government agencies that purchase and re-sell most home mortgages have stated that they may not accept loans for homes that have PACE loan financing against them. Additionally, the stagnant housing market of the past few years has seen a fall in home equity loans that may have been used to install solar systems.

“To encourage increased adoption of solar energy, there is a clear need for solar power to become both more efficient and more cost-effective relative to the coal-based electricity rate,” Rose says. “To meet the rise in demand and the need for improved energy efficiency at lower cost across the solar market, a number of new processes and new technologies are being researched and examined,” he continues. “SAFC Hitech’s goal now is, through collaborative agreements with strategic partners, to integrate new precursor usage efficiently to improve user processes and support the PV industry with a wide range of products suited to all competing technologies.”

Examples of SAFC Hitech's research team involvement with different approaches to commercially viable solar cells and the development of higher-efficiency, low-cost modules are outlined below:

  • III-V precursors for concentrated PV (CPV) applications – The combination of tandem III-V cells with concentrator technology has been proven to afford higher cell efficiencies. CPV increased optimized cell efficiencies from 20–25% to 41% by using materials capable of high efficiency at high light exposure in triple-junction designs with improved concentrator capabilities. To meet the expected growth in demand for installed capacity, thin-film CPV technology could be a key enabler, provided that it can be developed in a robust fashion and that costs can be reduced to be competitive. By focusing sunlight onto miniature high-efficiency tandem solar cells using high-concentration lenses or mirrors, CPV systems are expected to reduce the cost of solar electricity significantly, making it more commercially attractive to a wider audience. SAFC Hitech is focusing on the supply of high-purity chemicals at reduced cost to improve the process dynamics. Higher quality leads to higher efficiencies while lower raw material prices and more effective usage reduce overheads, providing a more attractive final product cost. In particular, metalorganic production is being scaled up to provide increased volumes in an economically favorable manner.
  • Si nanoparticles in oxide for Si-based solar cells - SAFC Hitech, along with a consortium of partners including CEA, INES, Tyndall Institute, TU Delft and Uppsala University, is participating in ‘Semiconductor Nanomaterial for Advanced Photovoltaic Solar cells’ (SNAPSUN), a European-based project that is developing thin-film coatings for standard silicon cells that aims to improve absorption across third-generation solar technology. Aiming to propose a clear and progressive approach toward optimized PV demonstration, with the active support of nanoscience and associated modelling, SNAPSUN’s primary goal is to show a PV proof-of-concept, with the potential for very high conversion efficiency. Scheduled to report its findings in March 2011, SNAPSUN is focused on Si-based nanotechnology and nanoscience studies to create a breakthrough semiconductor nanomaterial with high potential to solve issues of charge transport, along with related processes that will allow the fabrication of high-efficiency PV devices avoiding scarce expensive elements. Embedding nanoparticles in host matrices to enhance performance will require significant precursor development to solve compatibility issues. The approach to developing the novel technologies will be a two-fold path, with an exploratory process first to define the target structure then a production-compatible process to develop a commercial technology. SAFC Hitech will be involved in developing the latter process for industrial scale-up and implementation, with specific attention to chemical solution provision for stable cocktails capable of direct use to form the nanoparticle in matrix films by simple coating mechanisms.
  • CdTe/CIGS sources for thin-film devices - To support existing CdTe and CIGS device manufacturing on a large scale, SAFC Hitech says that it can provide chemicals for both vapor phase and chemical deposition techniques. The optimization of complete vapor deposition technologies (TCO, absorber and window layers) is being studied in an ongoing collaboration with teams involved in the PV21 SuperGEN project (the main UK government- and industry-supported university network), which is studying commercial aspects of all the main existing technologies along with the viability of new disruptive approaches. In particular, new materials and surface structuring to improve performance have been targeted. The potential to eliminate toxic, high-price, scarce elements from cell structures is highly attractive, says SAFC Hitech, provided that no decline in final product efficiency is seen and, more importantly, that the price per watt of generated power remains competitive.

SAFC Hitech says that its overall objectives are to support the development of technologies capable of improving solar cell products across the gamut of production processes currently proposed for high-efficiency, low-cost solar cell manufacturing in the future and to ensure that chemical products are available in the correct specification, volume and price to enable the deployment of sufficient device areas to meet demand.

See related item:

SAFC Hitech expanding TMG capacity in UK plant

Search: SAFC Hitech CdTe CIGS Solar cells III-V precursors