Comparison of the different CPV rating procedures: Real measurements in ISFOC

ISFOC has completed the first phase of its CPV plants installations with different technologies. Therefore, ISFOC is in a privileged position for contributing to define the new standards for the power and energy rating for CPV systems. During the first four months of the year 2009, ISFOC has measured the CPV plants using the proposed procedures of the Working Group 7 of IEC TC82 Committee. The results are presented in this paper. The four methods investigated are: The IEC draft "Concentrator Photovoltaic (CPV) Module and assembly performance testing and energy rating". This method is based on the 61853-1 PV standard and provides the PV module power (watts) at maximum power operation for a set of defined conditions The interpolation bilinear by Bill Marion which uses four l-V curves in different conditions. The American Standard Test Method for "Rating Electrical Performance of Concentrator Terrestrial Photovoltaic Modules and Systems under Natural Sunlight" ASTM E 2527-06. This regression based method has been used in USA for several years. ISFOC procedure for concentrator rating: This methodology has been described in several papers and it is used by ISFOC for the acceptance of the CPV power plants. It is based on a set of measurements in a short period of time which are translated to the standard conditions with equations based on the Shockley model. Only one set of measurements is needed to establish the nominal power of the CPV. The first two methods were proposed and are used for modules rating and not for systems, but CPV has only sense at array level, therefore we will try to use these methodologies also for HCPV systems.