Understanding kWh/kWp by comparing measured data with modelling predictions and performance claims

The performances of PV arrays are usually compared by the kWh/kWp produced. Several recent independent studies in European climates have found similar kWh/kWp (within experimental error ±5%) for different module technologies without a systematic bias in favour of any technology. Sizing programs that estimate kWh/kWp values usually predict the IV curve of a PV module with a 1-diode model to match the STC curve then correct for irradiance and temperature effects. They often predict higher kWh/kWp for thin film devices as their models give them better low light level performance than is measured. Measured weather parameters such as tilted plane irradiance and detailed dc performance of several technologies at ISET has been compared and contrasted with predictions from three different sizing programs. Many differences have been found between measured and modelled weather data, thermal coefficients and low light level dependency meaning kWh/kWp should not vary much between correctly declared PV technologies. If kWh/kWp variations are small (i.e. < ±5%) shown in Europe then other parameters have been suggested that can be used to differentiate PV technologies.