Detailed Estimation of Available Solar Energy in Japan

This study has been carried out to probe into the availability of using solar power generation as a substitutive power system for the fossil fuel in Japan. The available space the solar cell array could be installed is 10% for the plottage of major buildings, 0.5～2% for the flat land and a certain percentage for the appended facilities for road, etc. The generation capacity of the solar cell is assumed to be 100 W/m2 at peak time (the average value is 1/10).The generating power calculated from the conditions above is about 250GWp and nearly 75% of that is from the building plottage, and the available space for array installation is close to 0.66% of the gross land area. Also, based on the above estimate, the generating power is expected 286 billion kWh a year, which is about 30% of the total power generated (964 billion kWh in 1994), that is about 5% of the total power consumed (5.9trillion kWh in l994)