SAFC Hitech announces plans to address opportunities in solar apps

SAN FRANCISCO, USA: SAFC Hitech, a business segment within SAFC, a member of the Sigma-Aldrich Group, announced details of a number of areas and initiatives in which it is working within the solar industry, as the drive to encourage the mass market adoption of solar power gathers momentum.

As a leading global supplier of key 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) cells.

With the solar market expected to grow exponentially over the next decade - global solar capacity expected to be at a minimum of 125GW (125 billion watts) by 2020 - SAFC Hitech is focused on working to help address solar cell efficiency and the high cost of solar systems, historic barriers to the mass market adoption of solar. Looking ahead to future iterations of solar cell technology, the company is working closely with customers and research partners to develop new specialty chemical offerings to enable the fabrication of advanced, 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,” said Philip Rose, SAFC Hitech president.

As far back as 1957, Hoffman Electronics achieved 8 percent efficient photovoltaic cells, a figure that rose to 14 percent in 1960. In 1992, researchers at the University of South Florida developed a thin-film photovoltaic cell made of cadmium telluride, which was 15.9 percent efficient. As recently as June 24, 2010, SunPower Corp. set a new efficiency record for large area silicon wafer solar cells with a conversion efficiency of 24.2 percent. Essentially, it has taken over half a century for the efficiency rate to treble.

Cost has also been a critical factor preventing mass-market uptake of solar technology. With domestic systems and installation costing approximately $20,000 or more, adoption of solar energy for many consumers means seeking Government or State incentives, or home equity loans.

The United States government recently set aside $150 million to assist homeowners with the installation of solar panels and other energy improvements. However, this tax-assessed financing initiative, referred to as property assessed clean energy, or PACE, loans, and paid back over time by homeowners as an addition to their property taxes, has run into problems.

The two government agencies that purchase and resell 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,” continued Rose.

“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. 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 applications – The combination of tandem III/V cells with concentrator technology has been proven to afford higher cell efficiencies. Concentrator PV (or CPV) increased optimized cell efficiencies from 20-25 percent to 41 percent by using materials capable of high efficiency conversion 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 prove to be a key enabler, provided that it can be developed in a robust fashion and 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 by a significant amount, 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 provide for increased volumes in an economically favorable manner.

Si nanoparticles in oxide for Si based solar cells - SAFC Hitech, along with a consortium of partners which includes CEA, INES, Tyndall Institute, TU Delft and Uppsala University, is participating in Semiconductor Nanomaterial for Advanced Photovoltaic Solar cells (or SNAPSUN), a European-based project that is working to develop 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, the SNAPSUN project’s primary goal is to show a PV proof of concept, with potential for very high conversion efficiency.

Expected to report its findings in March 2011, SNAPSUN is focused on Si-based nanotechnology and nanoscience studies to create a breakthrough semiconductor nanomaterial material with a high potential to solve issue 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 be employed to develop the novel technologies will be two-fold path with an exploratory process first used to define the target structure and a production compatible process employed to develop a commercial technology. SAFC Hitech will be involved in the development of 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 the existing CdTe and CIGS device manufacture on a large scale, SAFC Hitech can provide chemicals for both vapor phase and chemical deposition techniques. Optimization of complete vapor deposition technologies (TCO, Absorber and window layers) are being studied for an ongoing collaboration with teams involved in the PV21 SuperGEN project - the main UK government and industry supported University network currently in place.

This project is studying the 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 solar cell structures is highly attractive provided no decline in final product efficiency is observed and more importantly the price per watt of generated power remains competitive.

SAFC Hitech’s 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 manufacture in the future and to ensure chemical products are available in the correct specification, volume and price to enable deployment of sufficient device areas to meet demand.