In joint research with Japan's New Energy and Industrial Technology Development Organization (NEDO), Tokyo-based Solar Frontier - the largest manufacturer of CIS (copper indium selenium) thin-film photovoltaic (PV) solar modules - has achieved record energy conversion efficiency of 19.7% for cadmium-free, thin-film solar cells measuring about 0.5cm2, as measured by the National Institute of Advanced Industrial Science and Technology (AIST). It has been ten years since the previous record of 18.6% was achieved in 2012 (by the CIS-21 collaboration).
The record was achieved using cells cut from a 30cm x 30cm substrate, rather than specifically developed small-area cells, demonstrating high potential for further increases, it is reckoned. Moreover, used the same fabication method to achieve the result as that used for mass-production: a process of sputtering followed by selenization. Solar Frontier has chosen this method over co-evaporation due to the greater efficiencies in mass production. The firm aims to surpass the existing energy conversion efficiency record of 20.3% set using the co-evaporation method.
"This new achievement in energy conversion efficiency indicates the high level of Solar Frontier's technology and the high potential of CIS technology," says Satoru Kuriyagawa, chief technology officer, Solar Frontier. "The CIS thin-film modules currently available from Solar Frontier have gained a reputation for high performance in actual power generation, as they are not easily affected by shadows or high temperatures. Now, even higher real-world performance can be expected by applying this new basic technology," he adds. "We will continue working to further enhance our technological capabilities with the aim of setting a world record for thin-film solar cells overall."
Solar Frontier's CIS modules are manufactured at its Kunitomi Plant in Miyazaki prefecture in southwestern Japan. Since the plant started commercial production in February 2011, it has steadily increased its production efficiency. Currently, the CIS modules produced there have a conversion efficiency that exceeds 13%, and the amount of electricity generated (kWh) per installed capacity (kW) exceeds that of other solar modules, it is claimed.
