Bifacial NICE Modules from High Efficiency n-type BiSoN Solar Cells

AbstractThis paper summarizes results from bifacial glass/glass NICE modules, using n-type BiSoN solar cells with efficiencies in the 20.0% range. A first series of industrial size (Sixty 156x156mm2) modules, fabricated under non-ideal conditions, exhibit a typical power of 250Wp under front illumination at STC conditions. Two modules have been installed and monitored at the ISC-Konstanz test site in El Gouna Egypt (27°N latitude). Monitoring data from the outdoor performance of these modules between the beginning of 2014 and August 2014 are analysed and compared to the data of a standard mono-facial reference module with an STC power of 255W. The bifacial modules show an average gain in generated power of 14.3% compared to the standard mono-facial reference module. During this monitoring period instantaneous effective peak powers of 313W were observed for the bifacial modules due to reflection from the ground in addition to the front illumination of the modules. Since bifacial modules produce high currents under bifacial operation, the current rating of standard junction boxes can become a critical factor. In this paper a newly developed junction box with a maximum current of 20A and a rated current of 17A is introduced

Experimental implementation of a silicon wafer tandem solar cell

We combine aluminum back surface field (Al-BSF) solar cell precursors with an additional rear side infrared active floating emitter in a tandem cell configuration. This emitter is implemented area selectively by fs-laser hyperdoping in a sulfurous atmosphere. Its design as a floating emitter conceals losses induced by the laser process as long as n-doping occurs. All processes are adapted and supplemented by just a single new process step

Influence of the Al-Si Alloy Formation in narrow dielectric barrier openings on the specific contact resistance

A full area Al-alloyed back surface field layer usually forms the rear side of standard p-type Si solar cells. However, a dielectric rear surface passivation with only small local contact openings has significant advantages over the standard fully covered Al back contact, and enables higher efficiencies on thinner wafers. This article presents a specific analysis of the formation of small localized contacts between Al and Si. We observe that the contact resistivity of screen printed Al fingers depends on the homogeneity of the Al-Si alloy formation below the contacts. The contact resistivity decreases when reducing the contact area, due to a more homogeneous alloy formation. The optimal contact formation is achieved with contact areas smaller than 50 – 80 mm in diameter