The global photovoltaic market has seen the rapid growth of two-sided module technologies in which the front and back of the panel produce energy. The scientific community and standardization bodies have had to adapt to this new situation and, in particular, develop new methods for measuring the power, efficiency and "bifaciality" coefficient of these modules.

    The characterization of a bifacial module cannot be limited to the standard measurement of the performance of its front panel. The rear panel must also be measured to define the “bifaciality” and to estimate the effective power of the module according to different albedos.

    On the initiative of SERIS (Solar Energy Research Institute of Singapore), the first international round-robin on bifacial modules according to the IEC TS 60904-1-2 standard was launched in 2018. Its aim: to enable laboratories from the world community to qualify their methods and equipment by characterizing the same references and comparing the reliability of their results. The focus of this round-robin[i] was on the characterization of bifacial photovoltaics in relation to the brand new standard dedicated to this technology which was drafted in 2019.

    The project took place over two years, bringing together 25 partners laboratories[ii] from America, Asia, Europe and Oceania, including the main certification, research and measurement instrumentation manufacturers. Eight panel references were tested by each of the teams, according to their own methods and with their own equipments.

    The results have just been delivered and the CEA - INES has been able to verify that the reliability of its measurements and methods for characterizing bifacial photovoltaic modules is equal to that of the recognized certification institutes worldwide. A guarantee of the quality and reliability of the gains announced by its laboratories!

    [i] In the scientific community, round robins are tests of identical samples by different laboratories. Laboratories organize them to validate test methods and/or assess the quality of their results.

    [ii] NREL, JRC, Fraunhofer-ISE, TÜV-Rheinland, AIST, SERIS, KIWA, SIPSI, CEA-INES, PI-Berlin, PI-China, CPVT, JET, AIT, CFV, Pasan, CSEM-EPFL, CSIRO, ISC, ESN/TNO, Eternal-Sun, IMEC, GSolar