A proposal of design method of cost effective large-scale PV system and configuration of PCS

In Japan, the system of Feed-in Tariff was started from last July. According to the act, the electricity energy generated from large-scale PV (LSPV) generating stations is bought for 42 yen per kWh including tax for 20 years. This price is about 2 times as large as a normal electricity rate. However it is still important to design the LSPV system reasonably in order to return high investment as soon as possible. We propose the design method of cost-effective LSPV systems which can utilize facilities effectively, with first. It is based on statistical and individual data of PV generation distribution which are issued by the association of weather etc. In the investigation of example case, it turned out that the LSPV system capacity can be adequate with 80% of the PV installed capacity. Next, for getting high performance, an adequate number of PV strings to connect to a large-scale power conditioner (LS-PCS) through a DC/DC chopper is examined in consideration of imbalances of PV modules. We found that the optimum number of strings should be determined in consideration of the configuration of LSPV systems, cost and the capacity of the LS-PCS, etc., for every LSPV systems.