Because of the Kyoto protocol and the limitation of natural resources, the renewable energies are being concerned. This paper investigates the generation expansion planning for a small standalone power system (e.g., 150 kW). This paper considers 25 kW wind-turbine-generator, 5 kW HCPV and 20 kW diesel generator. The reliability is considered for a period of 5 years to study the generation expansion. The advantage of renewable power generation is investigated through total cost and average price in the 15 years (average life span), compared with the traditional fuel cost. The weathers of Orchid Island and Mt. Jade in Taiwan are used as modes for illustration.