Abstract
This study aims at evaluating the possibility for market penetration of solar water heaters to utilize solar energy as thermal energy. Japanese government planet to introduce four times as many solar heaters as present plants. However, stable oil price in recent years results in decrease of solar heaters. The study investigated optimal setting of solar collector as well as energy saving per detached house, It was aggregated over three regions to estimate total possible energy saving in Japan. Because installing solar heater depends on the judgement by household from economic point of view, the acceptability function is assumed with respect to payback year. It was found that present cost condition resulted in no additional installation while 20% cost reduction would amplify the installation so as to achieve the governmental target in 2010.
