Progress in Photovoltaics最新文献

Over the past decade, silicon solar cells with carrier-selective passivating contacts based on polysilicon capping an ultra-thin silicon oxide (commonly known as TOPCon or POLO) have demonstrated promising efficiency potentials and are regarded as an evolutionary upgrade to the PERC (passivated emitter and rear contact) cells in manufacturing. The polysilicon-based passivating contacts also exhibit excellent gettering effects that relax the wafer and cleanroom requirements to some extent. In this work, we experimentally explore the impact of bulk iron contamination and polysilicon gettering on the passivation quality of the polysilicon/oxide structure and the resulting solar cells performance. Results show that both n- and p-type polysilicon/oxide passivating contacts are not affected by iron gettering, demonstrating robust and stable passivation quality. However, for a very high bulk iron contamination (1 × 10¹³ cm⁻³), the accumulated iron in the p-type lightly boron-doped emitter in crystalline silicon would degrade the emitter saturation current density. This can cause a reduction in both open-circuit voltage and short-circuit current. Meanwhile, this very high iron content (1 × 10¹³ cm⁻³) can further degrade the fill factor and temperature coefficient of the cells. On the other hand, for an initial iron content of 2 × 10¹² cm⁻³, which should be well above the iron level in the current industrial Czochralski silicon wafers, the resulting cells demonstrate similar performance as the control group with no intentional iron contamination. This work brings attention to both the benefits of polysilicon gettering effects as well as the potential degradation due to the accumulation of metal impurities in the p-type emitter region.

Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined, and new entries since July 2024 are reviewed.

This paper presents an outdoor performance monitoring method for degradation studies of perovskite modules, focusing on a large-area perovskite module (81.9 cm²) over a long-term monitoring campaign. The module underwent an industrial lamination process to prevent long-term degradation from environmental factors. The characterization procedure involved degradation correction and determining the temperature coefficients and electrical parameters of the module using initial days of measurements. The results demonstrated temperature coefficients for I_sc, V_oc, and P_m (α′, β′, and γ) of −0.071%·K⁻¹, −0.119%·K⁻¹, and −0.113%·K⁻¹, respectively, indicating a minimal temperature influence on this technology compared with conventional ones. Using this coefficient, the STC electrical parameters were retrieved from 1-min power output data, resolving the uncertainty of the indoor/outdoor IV curve measurements caused by the curve scan direction (JV hysteresis effect). We also highlight the initial remarkable capacity recovery effect of almost 16% during the first 2 days of operation. Additionally, a procedure that includes the IV curves analysis taken every 10 min and their translation to standard conditions has been implemented to evaluate the degradation of the module over the long-term outdoor campaign. The results show three different trends over the period.

Large-scale daylight photoluminescence imaging of crystalline silicon solar panels in utility-scale solar farms, whereby luminescence images of several hundred to thousands of panels are acquired simultaneously, was demonstrated by our group recently. Here, we demonstrate that photoluminescence images of large solar farm sections that are connected to the same central inverter uniquely contain quantitative information about voltage mismatch between series-connected strings of modules resulting from voltage variations between groups of modules. These voltage variations cause significant balancing currents between module strings when no or only low power is extracted from the solar farm. The impact of these balancing currents on the luminescence intensity is discussed. An analytical model to correct daylight photoluminescence images for these balancing currents is proposed and validated using experimental data.

The advantage of employing an n-type hydrogenated nanocrystalline silicon oxide (nc-SiO_x:H) layer as the front surface field (FSF) in silicon heterojunction (SHJ) solar cells is due to its low optical absorption coefficient and tunable refractive index. However, carbon dioxide (CO₂) gas, one of the major precursor gases in the nc-SiO_x:H layer, deteriorates the crystallinity, which is one of the key factors affecting cell performance. Here, we successfully deposited a nc-SiO_x:H FSF layer with high crystallinity for SHJ solar cells by using nitrous oxide (N₂O) as an alternative oxygen source instead of existing CO₂. Compared with the use of CO₂, the use of N₂O as an oxygen source can achieve a 10% ~ 15% increase in the deposition rate of the nc-SiO_x:H layer, which can shorten the total processing tact-time, thus having the potential to reduce production costs in large-scale industrial applications. The influence of N₂O as an oxygen source on the film properties was also investigated. By optimizing the proportion of N₂O in the precursor gases, we finally fabricated 274.5 cm²-area SHJ solar cells with an in-house average efficiency of 25.76%, which is approximately 0.1%_abs higher than that of their reference counterparts (using CO₂ as an oxygen source), and obtained a certified efficiency of 25.79% for the champion cell independently confirmed by the ISFH CalTeC in Germany.

A simple binary antimony selenide (Sb₂Se₃) absorber is evolving as an alternative photovoltaic material in thin film solar cells because of its unique properties and easy processing. Sb₂Se₃ thin films having good crystalline quality are grown via versatile thermal evaporation from pre-synthesized near stoichiometric compound material on molybdenum-coated soda lime glass (SLG) and borosilicate glass (BG) substrates. Following the systematic characterizations on the absorber films, substrate configured Sb₂Se₃/CdS heterojunction devices were fabricated and their photovoltaic characteristics have been studied using current density vs. voltage (J-V), dark J-V modeling, external quantum efficiency and capacitance vs. voltage measurements. The power conservation efficiency values of 4.88% and 5.04% were achieved for the devices fabricated on SLG and BG substrates, respectively with deficit in open circuit voltage. The obtained values are higher in comparison to the reported device efficiencies in substrate configured Sb₂Se₃ solar cells, in which the absorber is prepared through thermal evaporation. To understand the loss in open circuit voltage_, a compact equivalent circuit model was considered and identified the contribution of different shunt leakage paths in the devices. In addition to that, the device fabricated on the SLG was stable with minimal changes in its photovoltaic performance for a period spanning over 200 days. The results obtained are encouraging with scope for improving the device performance through interface engineering and back surface passivation strategies.