Practical experience of a 50 kWp photovoltaic system supplying power to a dairy farm on Fota Island, Cork, Ireland

Abstract

The Fotavoltaic Project is a 50 kWp photovoltaic system used to supply electrical energy to a 250-head dairy farm on Fota Island in Cork Harbour, Ireland. It is one of the fifteen pilot projects, ranging from 30?300 kWp, which have been built throughout Europe under the auspices of the Solar Energy Research and Development Programme of the EEC. The dairy farm was selected because its energy demand has the same seasonal variation as the output of a solar generator. The system consists of a 50 kW solar generator, a 600 Ah lead-acid battery, three 10 kVA self-commutated inverters which supply the dairy farm loads and a 50 kVA line-commutated inverter which delivers excess energy to the utility grid. The system operates automatically and is controlled by a microcomputer, which, in addition, monitors and records data for analysis. A VAX 11/780 computer at the National Microelectronics Research Centre continually displays the system's operation on a graphics terminal using data transmitted from Fota via a telephone link. The system began operating in June 1983 and data recording began in January 1984. During the peak milking period between March and August 1984, the PV array generated 20.52 MWh, 4.643 MWh was supplied to the dairy farm and 9.676 MWh was supplied to the utility grid. The paper describes the design of the system, the practical experiences gained and improvements which have been implemented since the system was installed.