Climatic Specific Energy Rating Analysis of Outdoor PV Field Data

Abstract

ABSTRACTThe IEC 61853 standard series define the Climatic Specific Energy Rating (CSER), which can be used within the photovoltaic (PV) community as a reliable and accurate tool to differentiate between PV modules performance for different reference climates. The CSER is assumed to represent the expected PV device operation under real‐world conditions. The rating model combines a set of measurements on modules with a numerical approach. So far, research has mainly focused on the implementation of algorithms to determine the input parameters and to calculate the CSER values based on indoor measurement performance data. There is lack of information and technical specification how to obtain these parameters from outdoor PV field data in natural sunlight. In the present study, we first estimated the CSER parameter (according to IEC 61853‐3) for a PV module tested indoor using input values measured or defined according to IEC 61853‐1&2 with associated measurement uncertainties. Then, we analysed long‐term outdoor field data of the same device for a period of 36 consecutive months in order to understand how the length and seasonality of the data acquisition period impacts the reliability of irradiance and temperature power matrix values, particularly in relation to CSER calculations. Uncertainties estimations for the outdoor procedure have been also defined for rating accuracy. The PV outdoor performance has been validated against its indoor counterpart. The results concluded that a period of 9 or 12 months provides a good compromise between accuracy, time and cost‐effectiveness. The time period may be reduced to 6 months if the meteorological conditions are sufficiently diverse in this time frame. The study might raise worthwhile discussion regarding the revision of the IEC 61853‐1 for determining the (G‐T) matrix of PV modules from outdoor measurements under natural sunlight. It could enhance important insights to the PV community since the CSER parameter may become a compulsory requirement for each PV module produced, imported or sold in Europe if the potential European Union (EU) Ecodesign Directive and the Energy Labelling Regulation will be implemented.