Progress in Photovoltaics最新文献

Amorphous silicon thin-film photovoltaics have been widely utilized in building-integrated photovoltaics (BIPV) due to their advantages of lightweight, flexible, and easily transportable properties. However, long-term exposure to natural environmental conditions leads to the gradual degradation of their properties. To investigate the effects of aging on the mechanical performance and stress-related electrothermal reduction of these photovoltaics, this study selects naturally aged amorphous silicon thin-film photovoltaics as the research subject. Uniaxial tensile tests and microscopic morphology characterization were conducted to analyze specimen mechanical behavior throughout the full loading process and to reveal the mechanisms influencing temperature and voltage responses. Experimental results indicate that the aged photovoltaics exhibit an elastic modulus of 4108 MPa and a tensile strength of 49.86 MPa. Structural failure occurs due to the fracture of the stainless steel substrate during loading, while electrical failure and temperature decrease are observed prior to the yielding stage, with the temperature drop occurring after electrical failure. Electro–thermal–mechanical response reveals that the loss of photovoltaic capability leads to a reduction in internal current, which subsequently induces the temperature decrease. These findings can provide valuable insights for evaluating the long-term operational performance and safety of building-integrated photovoltaics.

This study aims to enhance the conversion efficiency of Cu₂ZnSnSe₄ (CZTSe) thin-film solar cells under AM1.5G/indoor illumination by utilizing nanoimprint lithography to fabricate three types of nanostructures with periodic designs. These structures not only demonstrate efficiency improvements under both AM1.5G/indoor illumination but also exhibit good performance under high-angle incident light and weatherability tests. Under AM1.5G illumination, the surface with/without nanostructures shows an increase in conversion efficiency from 5.54% to 9.05%, while under indoor illumination, the efficiency increases from 2.93% to 5.09%. Additionally, the surface's periodic nanostructures slightly outperform the optical enhancement of indoor light compared with that under AM1.5G illumination. In terms of weatherability testing, the efficiency decay rate of CZTSe solar cells with structures is 34.81%, significantly better than the unstructured counterpart at 48.01%. Interestingly, with increasing etching time, the characteristics of CZTSe devices not only show improvements in optical design but also exhibit self-healing effects, enhancing interface defects and reducing carrier recombination. Thus, the improvements are not limited to optical properties but also extend to the interface layers of the device.

Perovskite solar cells (PSCs) are a new significant emerging solar photovoltaic source and have the advantages of low cost and high efficiency. However, hysteresis is common in PSCs and can significantly impact power generation efficiency and operational lifespan. In order to analyze the J–V hysteresis behavior with a circuit simulator, a new J–V hysteresis circuit model is firstly proposed by using the dynamic characteristics of dynamic capacitance to simulate the hysteresis behaviors in this paper. The proposed model can effectively and precisely simulate the various dynamic hysteresis behaviors for investigation. In addition, to mitigate the poor output power performance caused by hysteresis effects in PSCs in practical applications, the proposed circuit model is employed to analyze the impact of hysteresis on maximum power point tracking (MPPT). The results indicate that oscillations occur in both output voltage and current during the MPPT process. Then a dynamic boundary–based ROA (DB-ROA) variable step-size MPPT tracking method is introduced, which can effectively implement oscillation suppression, improve the power output, and reduce the tracking time. The simulation results and experimental data show that this method can effectively improve the performance of the output power.

Low-temperature soldered wire interconnection (LTSWI) is a technology utilizing many interconnect wires carried on a polymer foil to form electrical connections against cell gridlines without a separate soldering process. In this work, LTSWI module samples were characterized for material properties and assembly dimensions and subjected to accelerated aging experiments to induce degradation. A finite element analysis model was developed based on characterization results, to analyze internal stressors during environmental exposures. The polymer foil contains polyethylene terephthalate and low-density polyethylene layers, and solder composition was tin bismuth, which notably was not metallurgically bonded to cell gridlines. High temperature accelerated exposures created power loss up to 9% in minimodule samples, with fill factor losses implicating contact degradation. Posttest characterization identified solder-gridline cracking and wire-cell separation as contributing mechanisms. Finite element modeling demonstrated that wire-to-cell contact is maintained by polymer contraction post lamination but is reversible, resulting in contact loss and wire separation during high temperature exposure. Simulations also detected in-plane wire-to-cell displacements, driven by surrounding polymer motion in response to high temperatures and mechanical load. We hypothesize that the propensity for wire movement during environmental exposure damages the not-metallurgically bonded wire-gridline interface and contributes to LTSWI contact degradation. Because distinct from thermal expansion mismatches which damage traditionally soldered modules, current test protocols are likely not applying the intended acceleration factors to LTSWI modules. This work highlights how construction-specific accelerated testing may be needed for nontraditional module designs and provides a starting point for accurate LTSWI life assessment.

The energy rating of PV modules is related to its energy yield performance in specific reference climates. In contrast to the nominal output power, which is related to the standard test conditions (STC), the energy rating considers the interaction of the PV module characteristics with the reference climate conditions. The following PV module parameters affect the amount of produced energy: (a) temperature behaviour, (b) low irradiance behaviour, (c) spectral responsivity and (d) angular responsivity. To compare the energy yield performances of PV modules, the standard series IEC 61853 defines a specific metric, which describes the energy yield performance of a PV module by a single parameter, the Climate Specific Energy Rating (CSER). Whereas recent studies have focused on the harmonization of CSER calculation methods, our study provides a methodology for the calculation of the expanded CSER uncertainty (k = 2). As inputs, we use the measurement uncertainties of PV module parameters, stated by TÜV Rheinland test laboratory. For the six tabulated reference climates of IEC 61853, our work has shown that a CSER uncertainty in the range of ±2%–±2.3% can be achieved. The main contribution in the range of 80% is related to the uncertainties of output power measurements with solar simulators under variable module temperatures and irradiances (G–T matrix). The following are the uncertainties associated with PV module temperature calculation and the measurement uncertainty of the angular response curve. Both are dependent on the reference climate under consideration. The contributions of uncertainties in connection with spectral responsivity and data processing together appear to be of minor importance.