PHOTO: Professor Vivian Alberts, CEO of PTiP, with one of the panels produced at the plant in Techno Park, Stellenbosch
Using engineering technology from Singulus Technologies of Germany, the PTiP plant is being used to demonstrate the ability to manufacture solar cells and modules. The CIGS (copper indium gallium selenide) thin-film solar technology uses large glass substrates on which a very thin photo-active layer with a thickness of approximately 1.5 to 2.5µm is applied. This absorber layer consists of a compound semiconductor including the elements copper, gallium and indium with selenium and sulfur in a so-called chalcopyrite structure.
The total thickness of the active materials in the thin-film module is just three microns, compared to the traditional first-generation silicon technology with a thickness of more than 300μ.
PTiP, a spin-off from the University of Johannesburg (UJ), has been working on the development of CIGS solar modules for the past 20 years. The demonstration plant in the Techno Park near Stellenbosch was established on the back of the critical success demonstrated in the UJ research laboratories. This facility will serve as a state-of-the-art R+D facility for commercial-scale and market ready 1200mm x 600mm CIGS modules.
An estimated R180-million has been invested in the project to date. The Industrial Development Corporation (IDC) is a strategic shareholder as is the Technology Innovation Agency (TIA), an initiative of Department of Science and Technology.
With the new CIGS line, the development of modules can be improved with particular regard to the efficiency and the special demands of the African market.
Professor Vivian Alberts, CEO of PTiP, said the “commissioning and official opening of this CIGS pilot facility in South Africa confirms the goals of the South African government to support and promote alternative and renewable energies, based on locally developed IP and skills”.
“It is an important step for a successful energy policy in our country. The immediate goal is to set-up a commercially viable production plant for CIGS thin-film modules in South Africa in order to supply products with high local content to existing and future PV projects in South Africa,” he added.
The European Investment Bank already announced its support for the establishment of a PTiP production plant and the mass production of PV modules.
“With the core production equipment and support from our partner, Singulus, we are able to industrially and efficiently implement our developed process,” added Alberts.
The pilot plant, originally situated at the University of Johannesburg, started to produce semi-commercial products in 2006. Prof Alberts originally operated the UJ site. It was subsequently decided to move the research laboratories to Techno Park in Stellenbosch, in 2011. The park has been growing in popularity as an innovation hub in the Western Cape. PTiP is the first company in the world to licence the technology internationally. The processes and product characteristics are protected by worldwide patents in 17 countries.
“Stellenbosch is an environment that offers expertise for the commercialisation of the technology and present to the world,” said Prof Alberts. “The aim is now to establish a fully-fledged photovoltaic industry, train people and to stimulate job creation in the industry.
Singulus had been working with the UJ scientists and delivered the first laboratory systems in 2011.
Singulus CEO Dr-Ing Stefan Rinck said: “With the vacuum coating, the selenization as well as two work steps in the wet-chemical area, in total we supplied four key process steps for a CIGS line. With our partner PTiP, we intend to continue to successfully implement the additional expansion stages as well.”
Opportunities for plastic moulders
Although the thin-film modules can use flexible plastic films, glass is currently the preferred option to contain the CIGS layers. However, should the photovoltaic project yield the anticipated results and spread in popularity, several opportunities for plastic moulders exist, including the production of battery casings, support structures and cabling.
CIGS thin-film solar technology
In contrast to mono-crystalline or polycrystalline solar cells, thin-film modules only marginally lose performance amid low light or very high temperatures. This results in the fact that thin-film solar cells produce electricity earlier in the morning hours and later in the evening hours. Furthermore, thin-film solar modules can be used as a design feature for the front or the roof of buildings due to its homogenous surface and better visual appearance.
Singulus focuses on the market of CIGS solar cells with photoactive layers made of compound semiconductors. These thin-film cells have achieved laboratory efficiency levels of around 20% so far. The efficiency of modules is in a range from 13-15%, depending on the module size.
SINGULUS
Singulus Technologies is a market leader in deposition technology. Its systems are widely used for the vacuum coating of optical discs (CD, DVD and Blu-ray discs). It has carried this technology over for the production of crystalline and thin-film solar cells, which increase the efficiency of solar cells and reduce production costs.
In the Semiconductor segment SINGULUS TECHNOLOGIES focuses its activities on the vacuum coating of wafers with ultra thin layers for the production of MRAM memory, thin-film write/read heads and other semiconductor applications.
NOTE: CIGS (copper indium gallium selenide) solar cells are a direct bandgap semiconductor useful for the manufacture of solar cells. The CIGS absorber is deposited on a glass or plastic backing, along with electrodes on the front and back to collect current. As the material has a high absorption coefficient and strongly absorbs sunlight, a much thinner film is required than with other semiconductor materials. Devices made with CIGS belong to the thin-film category of photovoltaics (PV).
CIGS layers are thin enough to be flexible, allowing them to be deposited on flexible substrates. However, as all of these technologies normally use high-temperature deposition techniques, the best performance normally comes from cells deposited on glass. The performance was marginal compared to modern polysilicon-based panels, but advances in low-temperature deposition of CIGS cells have erased much of this performance difference, even with flexible designs.
The market for thin-film PV grew at a 60% annual rate from 2002 to 2007 and is still growing rapidly. As a result, a strong incentive to develop and improve deposition methods for these films that will allow lower cost and increased throughput exists.