The work in WP1 was comprised in three individual tasks (T). T1, a theoretical research study on PV failure modes and their association with certain degradation rates, performance losses and diagnostic patterns; T2, a theoretical research study on field reliability and fault diagnostics for the case of bifacial PV, being the emerging and future dominant PV technology; T3, PV monitoring and yield simulation studies in real field, i.e. for existing PV test sites.
A particular focus was given on understanding and defining the occurrence of cell crakcs, potential induced degradation and bypass diode failures throughout the early years of the PV plants' operational lifetimes, as well as the electrical and thermal/optical characteristics of different failure modes. In addition, thorough insights were gained into the reliability testing needs, the field reliability and the dominant (expected) failure modes specificially in bifacial PV modules, both in glass-glass and in glass-transparent backsheet configration.
The research activity in WP2 comprised of two main Tasks, T1 and T2. The former shed light on the physics, stress factors and reliability testing/modelling needs associated to PID for bifacial PV modules. On the other hand, the work of T2 added a sustainability perspective, focusing on the characterization/inspection, classification and reliability testing of repairable PV failure modes, for the re-use (second life) of failed/decommissioned PV modules, i.e. in a circular economy framework.
The key findings, in brief, included: i) the identification and underlying physics of the different PID mechanisms (i.e. shunting and polarization type, Fig. 1), ii) the thorough understanding of the different characteristic "signatures" of these PID mechanisms and their propagation, i.e. in terms of I-V, EL and EQE characterization measurement, as well as iii) the optimization of current PID testing practices for bifacial PV, to allow correct interpretation and distinguishment of such mechanisms.
Finally, in WP3, in view of the early termination of the MSCA fellowship, the envisaged work has not been fully completed, though it remains an ongoing activity within the research team of imec. The extension of imec’s energy yield simulation framework and its integration with reliability model for certain failure/loss mechanisms (PID, soiling) is (and will) based on the gained insights from WP1, WP2 and on a three-fold ongoing activity:
Monitoring and what-if simulations study at Kuwait’s PV test installation.
Energy yield simulations’ benchmarking study for IEA PVPS Task 13 ST2.1
