New World-Record for Low-Cost Thin-Film Solar Cell Efficiency

Photovoltaic modules will be the same price as ordinary roof tiles now with the EPFL’s Institute of Microengineering reaching a remarkable 10.7% efficiency for a single-junction micro-crystalline silicon solar cell, surpassing the previous world record of 10.1% held by the Japanese company Kaneka Corporation since 1998.

The efficiency increase was also achieved with only 1.8 microns of photovoltaic active material — 100 times less material than with standard wafer-based crystalline silicon PV technology, that achieves efficiencies of 20% currently.

“Deep understanding has been gained these last years in material quality, efficient light-trapping and cell design, which in combination with careful process optimization led to this remarkable world-record efficiency” says Simon Hänni, PhD student at the Photovoltaics-Laboratory (PV-Lab) IMT Neuchâtel.

Importantly, the processes new thin-film silicon technology can be scaled up to module (panel) production, enabling prices as low as 35 €/m2 (47 $/m2), reaching the price level of standard roof tiles, according to the EPFL scientists.

Since the development path employed to achieve the reported record efficiency can be continued, the scientists expect further potential of TF-Si multi-junction devices, which could be extended to achieve > 13.5% conversion efficiency with a minimum usage of abundant and non-toxic raw material at low costs (TF-Si PV modules implementing in their simplest form two glasses and few microns of zinc and of silicon for an easy recycling). The manufacturing process is also less energy intensive compared with crystalline wafers, with cell fabrication temperatures never exceeding 200°C.

Work leading to this result was supported by the Swiss Federal Office of Energy (SFOE), the EU-FP7 program, the Swiss National Science Foundation (SNSF), and the Commission for Technology and Innovation (CTI).