Thin Film

Today, silicon solar cells are still produced in almost equal shares from mono- and multi-crystalline silicon wafers. The authors here look at the scope for efficiencies in the wire sawing process for multi-crystalline silicon.

Thin-film solar cells based on chalcopyrite semiconductor Cu(In,Ga) (S,Se)2 compound (hereafter called CIGS or CIGSeS irrespective of the exact composition) have continuously drawn interest because of their progressively increasing high photovoltaic conversion efficiencies and the merits of long-term performance stability, high energy yield, low cost production potentials and other advantages for industrial manufacturing and application of solar.

Innovation in the field of thin-film cells, in addition to economy of scale and the manufacturing learning curve, is an important element in keeping the price of this technology competitive. Most papers on these cells focus on their technology; however, the economic potential of the technology is also important. Of even greater significance, a realistic estimation of the potential, along with the associated costs, of advanced technology, is part of the equation for profitability. Two examples of technology – metallic grids and texturing – are given in this paper; the designs are discussed, and a brief economic analysis is presented for various scenarios of the technologies. Although the profitability of these technologies can be considerable, it is shown that one should be wary of basing decisions purely on potential and on ideal scenarios, and how the cost of a technology can turn a great prospect into a trade-off.

First Solar is introducing new production lines to manufacture its 400W large-area ‘Series 6’ modules.

Leading CdTe thin-film module producer First Solar is shifting it business emphasis back to module sales after becoming a leading PV project developer as part of a mid-term business plan that takes advantage of its restored cost-per-watt advantage and two new module products that will be introduced in the coming years that are intended to further its competitive position. We analyze the key metrics behind the transition, such as R&D expenditure, module conversion efficiencies and production capabilities and cost reductions.

CIS thin-film module manufacturer Solar Frontier has signed a memorandum of understanding with Saudi Aramco and the Saudi Arabian National Industrial Cluster Development Program (NICDP) on the feasibility of establishing a thin-film module production plant in Saudi Arabia.

An efficient exchange of knowledge is essential to move the technology forward. In June 2016, the IW-CIGSTech workshop was organized for the seventh consecutive year in a row. This time, the event took place as a parallel event to the EU-PVSEC/Intersolar Europe in Munich. In the workshop, representatives from industry and academia gathered to discuss the latest developments in the fast-developing field of CIGS (Cu(In,Ga)(Se,S)2) based solar cells. As a result of last year’s workshop, a joint, community-wide effort resulted in the broadly acknowledged “White Paper for CIGS thin film solar cell technology”. In this article, we provide a brief impression of the progress and challenges reported in this year’s workshop.

Investors require a guarantee of a minimum lifetime for PV installations. It is tempting to provide such a guarantee for a longer lifetime simply by specifying test conditions that are more and more severe. In this paper it is argued that, with a more detailed understanding of the basic mechanisms determining cell material behaviour under specific exposure conditions, not only can the inherent lifetime of solar cells and modules be improved, but also the predictive value and effectiveness of lifetime testing. An overview of the literature contributions regarding the influence of damp-heat exposure of the layers in Cu(In,Ga)Se2 (CIGS) solar cells is presented.

A critical failure mechanism for PV modules is the degradation in performance as a result of exposure to temperature and humidity. In the case of flexible PV modules, moisture-induced damage becomes a greater concern, since the moisture resistance of barriers and polymer packaging is expected to be lower than that for conventional glass–glass PV products. The work presented here is aimed at establishing, through the use of accelerated testing, the field lifetime of flexible PV modules with regard to moisture-induced degradation.

Of the various copper indium gallium diselenide (CIGS)-formation processes, a so-called ‘two-stage process’, consisting of sputtering and selenization, has been successfully applied in large-scale production thanks to its stable process scheme and high-fidelity production equipment. A CIGS module with a power of 231W, corresponding to a total area-based efficiency of 16% for 902mm × 1,602mm, was demonstrated when this twostage process was employed in a pilot production line at Samsung (although all the technology concerning CIGS production has now been transferred to Wonik IPS, whose main business is to provide production equipment for the semiconductor and display industry). The high-power module suggests significant potential for CIGS modules to compete with multicrystalline Si modules in terms of both cost and performance. This paper addresses the important process technologies for achieving high efficiency on large-area substrates, and presents a cost analysis using the data obtained from the operation of the pilot production line. As a result of the synergistic effect of low material cost and high efficiency of the two-stage process, the CIGS manufacturing cost is expected to be reduced to US$0.34/W.