Performance of the Mead, Nebraska, 25 KWp Photovoltaic Solar Energy System and Comparison with Simulation

摘要

A photovoltaic solar energy system has been providing power for irrigation and crop drying at an agricultural field station of the University of Nebraska. The system, developed and maintained jointly by MIT/Lincoln Laboratory and the University and under contract to the US Department of Energy, consists of a 25 kWp PV array, a battery subsystem, an inverter, a controller, and a data collection and management system. Field data indicate that the PV array performs up to expectations if allowance is made for degradation. The array operates at an efficiency (based on cell area) of between 7 and 8%; the battery subsystem at an in-out efficiency of 83%, and the inverter at 87%. During the irrigation season the system delivers 70% of the energy provided by the PV array to the pump motor. Approximately 10% of the array energy is wasted when the battery is in a fully charged state and the array power exceeds the load. Performance of the system was compared with the results of a computer simulation. This comparison showed agreement to within +- 5% on daily energy totals for array output, inverter input, battery input and output. (ERA citation 04:054321)