Pilot production of large-area CuInS2-based solar modules

A pilot production of CuInS₂-based thin-film solar modules has been established in Berlin, Germany. To date, its 125 cm × 65 cm modules have produced an aperture area conversion efficiency as high as 7.6%, and avenues towards even higher performance levels have been identified. The pilot production features industrially-proven sputtering technology for material deposition and a new rapid thermal process allowing a five-minute sulfurization cycle time. The first thousand modules produced (representing a total of 45 kWp) were subjected to statistical analysis documenting the continuous enhancement of module power over the early months of pilot production. Transient effects were found that influence module I(V) characteristics cause inaccurately low module power measurements when flasher-type sun-simulators are used in testing — a phenomenon correctable by the introduction of a pre-test light-soaking procedure. In order to verify the post-light-soaking test results data from outdoor measurements taken under standard test conditions as well as performance data of outdoor PV systems were analyzed. A higher energy output on a Wh/Wp-basis found for CuInS₂-based solar modules than for polycrystalline silicon-based solar modules is presumed to be due to a lower temperature coefficient. For evaluating the long-term future potential of the new CuInS₂-based technology, a cost model is introduced to assess the economic relevance of uptime, cycle time and yield values, and to show that both efficiency and productivity are crucial for high-capacity manufacture of thin-film solar modules.