Zhigang Xie

>23% High-Efficiency Tunnel Oxide Junction Bifacial Solar Cell With Electroplated Cu Gridlines

Based on the metal-insulator-semiconductor concept, Triex cell is a proprietary device structure that combines a tunnel oxide junction with doped a-Si thin-film emitter layers on n-type Czochralski silicon wafers. A simple patterning process is used along with cost-effective copper electrochemical plating to form the electrodes. This paper reports a >23% high-efficiency Triex solar cell, postoptimizing key process areas to improve passivation, junction quality, and shading effects. High open-circuit voltage (Voc) of 739 mV and good fill factor of 80.5% have been demonstrated on a 6-in solar cell. A champion 380-W Triex bifacial module is also validated under standard test conditions.

High efficiency bifacial modules in outdoor testing

High-efficiency tunnel oxide junction cells are based on the Metal-Insulator-Semiconductor concept, which combines a tunnel oxide junction with doped a-Si thin film emitter layers on n-type CZ silicon wafers. The cells are bifacial by design and allow for almost equal power generation from the front and from the back. Packaged inside a module with transparent front and backside allows for light capture from both sides of the module in a field installation. For the first time for this tunnel oxide technology, outdoor performance and system data are presented and evaluated. The impact of climate, mounting, testing procedure and module design are studied. The results demonstrate the complexity of a bifacial outdoor system with significant yet difficult to predict performance gains over traditional module designs.