A comparative study of the impact of horizontal-to-tilted solar irradiance conversion in modelling small PV array performance

The capabilities of modelling the performance of photovoltaic (PV) systems depend both on the available PV models and on the accuracy of the input information that the models need. The meteorological input to any model consists mainly of the solar irradiance incident in the module as well as other influencing variables (temperature, wind speed, etc.). Since incident solar irradiance on characteristic inclined surfaces is not frequently available, the performance models use to incorporate specific models for computing tilted solar irradiance from the other components (global horizontal and direct normal) with higher availability. In this work, System Advisor Model (SAM), a performance model, has been used to analyze the contribution of some well-known transposition models to the uncertainty in modelling the system performance. The study has been performed for a small-scale photovoltaic array of CdTe placed at the roof of a building in Madrid. The performance predicted by SAM is rather good with around 3% of root mean squared error in the daily AC power when the input irradiance is taken from experimental measurements at the modules tilt angle. A 3% of an additional error increase compared to the results with the experimental tilt irradiance was observed for using all of the transposition models included in SAM. Published by AIP Publishing.