important topic
The Solar Plant Performance Ratio Measure The Performance Ratio is a measure of the quality of a PV plant that is independent of location, and it therefore often described as a quality factor. The performance ratio (PR) is stated as percent (%) and describes the relationship between the actual and theoretical energy outputs of the PV plant as described in the below formula. The closer the performance ratio value determined for a PV plant approaches 100 %, the more efficiently the respective PV plant is operating. The following specific values are needed to calculate the Performance Ratio (PR): 1- Analysis Period: The optimum analysis period for calculating the performance ratio is 1 year. 2- Measured Average Solar Irradiation (kWh/m^2): To calculate the irradiation value for 1 year, for example, you first have to calculate the monthly averages. To do this: - Add the daily average values for a given month. - Divide this amount determined by the number of days in the month, which gives you the monthly average value. In this way you can calculate the monthly average values for all 12 months of the year. To calculate the annual average value, you simply add the 12 monthly averages and divide the total by the number of months, i.e. 12. 3- Area of the PV plant: You can calculate the total area of the PV system by looking at the dimensions of your selected module. 4-Efficiency of the PV modules: You can obtain the efficiency of your PV plant from the data sheet of the PV module. 5-Actually measured plant output :You can read this value from your power export meter at the end of year. In real life, a value of 100 % cannot be achieved, as unavoidable losses always arise with the operation of the PV plant (e.g. thermal loss due to heating of the PV modules). High-performance PV plants can however reach a performance ratio of up to 80 %.