Technical Papers

Standardized requirements for the quality of PV modules, solar cells and wafers are given in the according IEC norms (e.g., IEC 61215, 61646, and IEC 61730 for modules). However, the manufacturers of cells purchasing wafers and the module manufacturers purchasing cells want information beyond the final check of the product and to monitor each step during the production process to identify harsh handling and/or machine faults at the earliest stage possible. With consequential improvements of the process enabled, continuous improvements in throughput and yield improvement of the factory are likely, also allowing an early feedback on quality issues to the raw material supplier. Furthermore, by knowing all characteristics and factors of the cell and the module, prediction of electrical energy yield during the life cycle of a PV power plant is becoming more accurate and more reliable.

The importance of rapid and accurate measurement of the electrical power output and related characteristics of photovoltaic (PV) modules or panels concluding the manufacturing process cannot be overemphasized. Even though these modules will likely be deployed under a variety of outdoor solar illumination conditions, they must be tested under a set of standard conditions to assure consistency of results demanded by both the manufacturer and the customer. The ability to provide a measurement tool for this critical manufacturing step that possesses the proper specifications and qualities, ranging from spectral accuracy to ease-of-use, is imperative.

Increasing the efficiency and yield of production line processes forms an integral part of PV manufacturers’ technology roadmaps. For their next generation production lines, non-contact processing equipment is considered essential. This prioritizes laser-based processing, already established at several steps in c-Si and Thin-Film cell manufacturing. This paper summarizes the key issues when using lasers within PV production lines.

Design and performance qualification testing of PV modules consists of a set of well-defined accelerated stress tests with strict pass/fail criteria. ASU-PTL is an ISO 17025-accredited testing laboratory and has been providing photovoltaic testing services since 1992. This paper presents a failure analysis on the design qualification testing of both crystalline silicon (c-Si) and thin-film technologies for two consecutive periods: 1997-2005 and 2005-2007. In the first period, the industry was growing at a slower rate with traditional manufacturers, with qualification testing of c-Si technologies being primarily conducted per Edition 1 of the IEC 61215 standard. In the second period, the industry was growing at an explosive rate with new manufacturers joining the traditional manufacturers, while qualification testing of c-Si was primarily conducted per Edition 2 of IEC 61215. Similar failure analysis according to IEC 61646 has also been carried out for thin-film technologies. The failure analysis of the test results presented in this paper indicates a large increase in the failure rates for both c-Si and thin-film technologies during the period of 2005-2007.

Each year, the photovoltaic market grows at a two-digit growth rate. However, the resulting economy-of-scale effects are not enough to achieve grid parity on their own. In order to reduce the production costs to grid parity level, new concepts and ideas must be realised as the basis for a photovoltaic factory. There are four main requirements that must be fulfilled in order to adhere to this cost reduction strategy: a highly integrated factory; automated and stable processes; a production control system (PCS) that provides the statistic data in order to continually optimise the processes; and an optimally-sized aligned production capacity.

Thin-film solar cell manufacturing is poised to make a giant leap in scale with the birth of the gigawatt fab. Commercial thin-film plants are typically sized based on the capacity of the production line from the chosen equipment supplier. In most cases, initial investments have been for a single line, typically with an output capacity of no more than 60MWp. This period of initial development has allowed the industry to prove the robustness of the technology and capabilities of the equipment, as well as to understand the significance for the cost-per-watt of key cost drivers such as materials reduction, cell efficiency increases, and productivity. While large-scale manufacturing will positively impact costs, it presents a unique set of challenges for equipment and material suppliers, as well as the engineering and contracting companies tasked with designing, building, equipping and running a facility on this scale. In this paper, we present the insights of two specialty companies in the solar industry. Turner and Townsend, a design and project management consultancy, and Linde, glass manufacturer and gas and chemical company - share their views of the challenges of the gigawatt fab in three dedicated sections.

Thin-film silicon solar cells are a potentially low-cost alternative to solar cells based on bulk silicon that are commonly used in the industry at the present time. However, a major drawback of the current epitaxial semi-industrial screen-printed cells is that they only achieve an efficiency of about 11-12%. By upgrading their efficiency, this kind of solar cell would become more attractive to the photovoltaic industry. The optimization of the front surface texture by dry texturing based on a fluorine plasma and the introduction of an intermediate porous silicon reflector at the epi/substrate interface (multiple Bragg reflector) has proven to result in an efficiency boost up to about 14%.

Until recently, Solyndra had been one of the stealthiest thin-film photovoltaics operators, its glistening, prominently logoed headquarters building reminding tech-savvy commuters plowing up and down the I.880 corridor near Fremont, CA, of how little they knew about the company. But Solyndra has finally let the sunshine in and come out of the closet — even if it hasn't quite changed some of its stealthy ways. After a well-planned media and analyst rollout, the public knows that for this copper-indium-gallium-(di)selenide (CIGS) thin-film PV manufacturer, the world — or at least its solar-module form factor — is not flat. Like many TFPV purveyors, Solyndra loves glass as a substrate, but the company's meter-long CIGS-coated cylindrical modules look like a fluorescent light-bulb tube, not just another rectangular slab of the smooth stuff.