The purpose of this study is a proposal of the utilization of the exhaust heat from Solid oxide fuel cell (SOFC). In near future, the household SOFC will prevail, and exhaust heat produced with the SOFC's power generation must be used as the cogeneration system. SOFC has the high energy conversion efficiency because it operates at high temperature between 700 degree C and 900 degree C. But there is no utilization of exhaust heat in summer season while for the house heating in winter season. We devise the n-pentane refrigeration system using the ejector. It is elucidated by numerical calculations that coefficient of performance (COP) of this system is about forty percent. Although this is lower than the ideal cycle, the ejector system with n-pentane will be available as air-conditioner for domestic use.