Abstract
The surplus electricity generated in the residential photovoltaic (PV) system is sold by a customer and purchased by a utility. So the purchase and the sale prices influence the diffusion of PV system. In this paper, the purchase price and the sale price are calculated from the utility and the customer sides, respectively. Parameters are future years (2005, 2015, 2025) and the diffusion ratio of PV system (0, 2, 4, 6, 8, 10%). First, from viewpoint of the utility side, the optimum mix of electric generation sources and the generation curves are calculated using the linear programming method. The result leads to the purchase price at which the utility makes a profit. A representative result shows the purchase price has to be lower than 8.2 yen/kWh in case of the diffusion ratio being 10% and the year being 2025. Next, from viewpoint of the customer side, the PV system cost and the electricity charge are calculated supposing that the PV system cost decreases with increasing of the annual productivity of PV module and the existing electric charge system remains to 2025. The result leads to the sale price at which the customer makes a profit. A representative results show that the sale price has to be higher than 13.8 yen/kWh at the same parameter as above. It is concluded that a carbon or environmental taxes are necessary to fill up this big gap between the purchase (utility) and the sale (customer) prices.
