To show the huge potential of PV systems, the authors have been studying the feasibility of large-scale PV plants. If a PV module cost is assumed to be 100Yen/W, it gives the electricity at a cost of 7.70-13.12Yen/kWh for a 100 MW plant size located at 6 desert sites around the world, considering the site irradiation, local labor cost, etc. for each site. In spite of the fixed, flat plate, the cost can reach a fairly low level, The station will be composed of 20 sub-units x 10 units of 500 kW optimum size sub-units.