Photovoltaic Power Generation

Abstract

Dissemination of photovoltaic (PV) electricity generation systems in Japan has been triggered by the start of the feed-in-tariff scheme in 2012, and the capacity of installed PV has increased almost linearly each year since then. Accordingly, the system cost of PV has decreased drastically such that the levelized cost of electricity (LCOE) of PV in Japan will reach 14 JPY/kWh in 2020, thereby creating a situation of so-called grid parity. Key issues for such a low LCOE are cost reduction of high-efficiency (>20 %) silicon PV modules and development of improved thin-film PV modules with slight material consumption and simple fabrication processes. The ceiling of PV installation capacity is likely determined by the acceptance of existing electrical grids; capacity is expected to be 70–165 GW by 2030. To make PV electricity generation compatible with existing grids, large-capacity electricity storage should be coupled with PV such that electricity generated by PV can be levelized for several days. Such storage systems include redox-flow batteries and hydrogen (H2)-based energy storage combining water electrolyzers and fuel cells. Ultimately, large-capacity PV installations will be in countries of strong solar irradiance and combined with chemical energy transport. Concentrator PV modules with >35 % efficiency and abundant direct solar irradiation will cause LCOE to be much less than 7 JPY/kWh (NEDO target for 2030), and H2 generated by such low-cost PV electricity will be transported to Japan using H2 carrier technology that is currently under development.