30 years trajectory of a solar photovoltaic research

A review is given on a research trajectory of the solar photovoltaic PV science and engineering in recent 30 years. Firstly, an episode of starting the PV research related to the environmental issue is confided, then briefly overviewed with a story how it started the Sunshine Project in 1973. Secondly, a motivation to start the amorphous semiconductor research is explained to fabricate a synthetic semiconductor which could be design the band gap energy. As an example of the material processing, fabrication of the ternary Si-As-Te amorphous semiconductor in the space by the Space lab J and also amorphous Silicon alloys are introduced together with their essential advantages of the material system in view of both physics and technology as new type of physics semiconductors. Thirdly, as an application of the amorphous silicon material system, a series of high efficiency R and D efforts are demonstrated such as inventions of the a-SiC/a-Si heterojunction solar cell and of the stacked solar cells having the junction structures of a-Si//poly-Si, a-Si//nc-Si etc. In the final part of the paper, some new strategies to develop photovoltaic industry in Japan are introduced. The project milestone up to 2010 in the new Sunshine project and present status of the industrializations are summarized and discussed.