1. Department of Energy and Environmental Science; Nagaoka University of Technology; Nagaoka Japan
2. Research Center for Photovoltaics; National Institute of Advanced Industrial Science and Technology (AIST); Tsukuba Japan
3. Renewable Energy Research Center, Fukushima Renewable Energy Institute; National Institute of Advanced Industrial Science and Technology (AIST); Koriyama Japan
4. Department of Mechanical Engineering; Nagaoka University of Technology; Nagaoka Japan