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DOE OSTI2018

Elucidating potential-induced degradation in bifacial PERC silicon photovoltaic modules

This paper elucidates the behavior and underlying mechanism of potential-induced degradation (PID) on the rear side of p-type monocrystalline silicon bifacial passivated emitter and rear cell (PERC) photovoltaic modules. At 50 degrees C, 30% relative humidity, and -1000 V bias to the solar cells with aluminium foil on the rear glass surface, the rear-side performance of bifacial PERC modules at standard testing conditions degraded dramatically after 40 hours with a 40.4%, 36.2%, and 7.2% loss in maximum power (Pmpp), short-circuit current (Isc), and open-circuit voltage (Voc), respectively. The front-side standard testing condition performance, on the other hand, showed less degradation; Pmpp, Isc, and Voc dropped by 12.0%, 5.2%, and 5.3%, respectively. However, negligible degradation was observed when the solar cells were positively biased. Based on I-V characteristics, electroluminescence, external quantum efficiency measurements, and the effective minority-carrier lifetime simulation, the efficiency loss is shown to be caused by the surface polarization effect; positive charges are attracted to the passivation/antireflection stack on the rear surface and reduce its field effect passivation performance. Extended PID testing to 100 hours showed an increase in device performances (relative to 40 hours) due to the formation of an inversion layer along the rear surface. In addition, replacing ethylene-vinyl acetate copolymer with polyolefin elastomer films significantly slows down the progression of PID, whereas a glass/transparent backsheet design effectively protects the rear side of bifacial PERC modules from PID. Furthermore, PID on the rear side of bifacial PERC modules is fully recoverable, and light greatly promotes recovery of the observed PID.

14 SOLAR ENERGY↗

DOE OSTI2023

Potential induced degradation in c-Si glass-glass modules after extended damp heat stress

Traditional Glass-Backsheet (GB) photovoltaic (PV) modules have been the industry standard for a long time, but the Glass-Glass (GG) modules are quickly rising in popularity. PV modules installed in hot-humid climates with high string voltages can undergo potential induced degradation (PID). So far, to the best of our knowledge, only fresh modules with strong interfacial adhesion have been investigated for PID. However, in reality, the PV modules have weak interfacial adhesion after a few years of field exposure. Therefore, it is essential to evaluate PV modules with weakened interfaces. In this study, we investigated the PID susceptibility of PV modules with weakened interfaces after subjecting them to 2000 hours of damp heat (DH2000) at 85°C/85% relative humidity (RH) in an accelerated environmental chamber. Fresh GG modules were also stressed for PID to compare with PID degradation of DH-stressed modules. Pre- and post-characterization tests were done before, between, and after each stress method to determine the changes in electrical performance, cell metallization properties, and hotspot properties. It is observed that fresh GG modules showed little/no degradation (less than 1%) in maximum power (Pmax), whereas the GG modules that underwent sequential DH and PID degraded by 11% to 12%. Potential mechanisms for these degradations are also presented. Furthermore, the results presented in this study are critical for the industry, considering that the bifacial modules with GG construction will be dominant in the next 10 years.

14 SOLAR ENERGY↗

DOE OSTI2024

Incompatibility as a Resource for Programmable Quantum Instruments

Quantum instruments represent the most general type of quantum measurement, as they incorporate processes with both classical and quantum outputs. In many scenarios, it may be desirable to have some “on-demand” device that is capable of implementing one of many possible instruments whenever the experimenter desires. We refer to such objects as programmable instrument devices (PIDs), and this paper studies PIDs from a resource-theoretic perspective. A physically important class of PIDs are those that do not require quantum memories to implement, and these are naturally “free” in this resource theory. Additionally, these free objects correspond precisely to the class of unsteerable channel assemblages in the study of channel steering. The traditional notion of measurement incompatibility emerges as a resource in this theory since any PID controlling an incompatible family of instruments requires a quantum memory to build. We identify an incompatibility preorder between PIDs based on whether one can be transformed into another using processes that do not require additional quantum memories. Necessary and sufficient conditions are derived for when such transformations are possible based on how well certain guessing games can be played using a given PID. Ultimately our results provide an operational characterization of incompatibility, and they offer semi-device-independent tests for incompatibility in the most general types of quantum instruments. Published by the American Physical Society 2024

Physics↗

DOE OSTI2016

SU-F-J-10: Sliding Mode Control of a SMA Actuated Active Flexible Needle for Medical Procedures

Purpose: In medical interventional procedures such as brachytherapy, ablative therapies and biopsy precise steering and accurate placement of needles are very important for anatomical obstacle avoidance and accurate targeting. This study presents the efficacy of a sliding mode controller for Shape Memory Alloy (SMA) actuated flexible needle for medical procedures. Methods: Second order system dynamics of the SMA actuated active flexible needle was used for deriving the sliding mode control equations. Both proportional-integral-derivative (PID) and adaptive PID sliding mode control (APIDSMC) algorithms were developed and implemented. The flexible needle was attached at the end of a 6 DOF robotic system. Through LabView programming environment, the control commands were generated using the PID and APIDSMC algorithms. Experiments with artificial tissue mimicking phantom were performed to evaluate the performance of the controller. The actual needle tip position was obtained using an electromagnetic (EM) tracking sensor (Aurora, NDI, waterloo, Canada) at a sampling period of 1ms. During experiment, external disturbances were created applying force and thermal shock to investigate the robustness of the controllers. Results: The root mean square error (RMSE) values for APIDSMC and PID controllers were 0.75 mm and 0.92 mm, respectively, for sinusoidal reference input. In the presence of external disturbances, the APIDSMC controller showed much smoother and less overshooting response compared to that of the PID controller. Conclusion: Performance of the APIDSMC was superior to the PID controller. The APIDSMC was proved to be more effective controller in compensating the SMA uncertainties and external disturbances with clinically acceptable thresholds.

60 APPLIED LIFE SCIENCES↗

DOE OSTI2016

100 TeV pp collisions, Higgs type, PYTHIA8 generator: tev100pp_higgs_pythia8

Higgs production. Inclusive productions via gg2Httbar and qqbar2Httbar. Add decay channels. Tune=5 for pp. 20000 events per files. MRST2008LO PDF. Other settings: Sliming: (pT>0.4 GeV) and (PID=5 || PID=6) or PID>22 && PID<38) or PID>10 && PID<17).