Analysis of Dissemination of Residential PV Systems in Japan

Abstract

SUMMARY This paper focuses on residential photovoltaic systems in Japan. It projects the installation and installed capacity of residential photovoltaic systems by analyzing the correlation between their payback period and annual installation in new and existing homes. Exponential and hyperbolic curves are used for correlation analysis. However, the exponential curve gives a better fit than the hyperbolic one. PV installation in new houses shows a stronger correlation with the payback period than with existing houses. For the installation projections, target and delayed scenarios are assumed. In the target scenario, the target price is achieved as planned. However, it is achieved later in the delayed scenario. Ongoing subsidies and feed-in tariffs are also assumed. Based on the results of the analysis, the target cumulative installation and installed capacity are achieved in the target scenario. They are not significantly affected even without subsidies and feed-in tariffs. But they are reduced by almost half in the delayed scenario compared with the target scenario. This means that systemic price reductions resulting from research and development as well as mass production are more effective than ongoing dissemination promotion programs. To achieve the target capacity, not only cost reductions but also conversion efficiency improvements through research and development are indispensable.