We provide reliable verification of module performance in cases when achievement is under the labeled power rating and tolerance levels. We verify the efficiency of crystalline silicone and thin-film PV modules based on a precise determination of output under Standard Test Conditions (STC) as well as ascertain the aperture area relevant e.g. for world record efficiency measurements. Our verification measurements comply with applicable international standards. We maintain state-of-the-art laboratories with comprehensive high-tech measuring equipment. We implement qualified class AAA solar simulators and primary calibrated reference cells traceable to the World PV Scale (WPVS) to attain precise measurements at the lowest level of uncertainty.