The analyses of the performance of a complete photovoltaic system require precise
measuring equipment in order to obtain reliable comparative results. This paper presents a
computer-based instrumentation system suitable for a characterization of photovoltaic
conversion chains. Consisting in a data acquisition stage, a data processor, photovoltaic
generators and power conditioners, the system evaluates the respective efficiency of
maximum power point tracker (MPPT) and power conditioner. The efficiency of unknown MPPT
functions is estimated with great accuracy by means of an extremum control-based MPPT used
as a reference. Efficiency evaluations of two photovoltaic battery chargers during 4 days
illustrate the estimation procedure and the system test facilities.