Operating Strategy of a Stand-Alone Photovoltaic/Diesel/Battery Power System

A new method for operating a stand-alone photovoltaic/diesel/battery system is presented in this paper. The diesel generator is controlled so that the state of charge (SOC) of the battery may be maintained at a certain specified charge level in daily time. The battery is discharged when the SOC is higher than the specified charge level and charged when lower. A simulation is carried out over one year using the hourly data of electric load, insolation intensity, and atmospheric temperature on Kamishima Island, Japan in 1996. The minimum specified level is pursued in every day so that the fuel consumption is minimum. This method is compared with other operating methods: a conventional operating method maintaining the battery charge level at the full level (FCL), and Dynamic Programming (DP) operating method. The results show that for diesel generator fuel consumption, this method is superior than FCL, although not to the DP.