Influence of initial power stabilization over PV modules maximum power

Measurements that suppliers offer in flash lists, unfortunately do not always fit the actual power measured in independent laboratories like CIEMAT. In fact, independent measurements usually appear lower than those printed in the label and sometimes a value beyond the allowed tolerance pointed by the manufacturer in the same label. In addition, a valuable power reduction has been reported when Standard IEC - EN 50380 is applied (according to this, PV module must be exposed to sunlight more than 20kWh/m2 previously to performing the measurement), crystalline PV modules usually decrease its power around 1%, but descends greater than 4 % have also been reported. These power losses are only detected after the mentioned power stabilization