Solar Energy最新文献

This work documents a full-year performance of a new design of a non-tracking zero-latitude-tilt external compound parabolic concentrator (XCPC) solar thermal system called Non-tracking Asymmetric Shadeless (NASH) concentrator. The system has a horizontal-aperture design that offers several advantages in terms of land use efficiency because of zero row-to-row spacing, reduced capital costs, and improved heat management. The horizontal aperture (no tilt) design enables it to be scaled to a large area easily without lost area from row-to-row shading as experienced by a tilted design. The system was tested at the University of California Merced, Castle test facility for a full year. The data are analyzed to investigate the system efficiency and thermal energy generated during the year. The system generated 766 kWh/m² during 2022 with annual efficiency of 41 %. A steady-state model is developed to predict the system performance based on the direct- and diffuse-light optical efficiencies, radiative and manifold heat losses, and observed soiling rate. The system efficiency decreased by up to 14 % over a month due to soiling in this test location. The model gives a good estimation of the steady-state operation during July and predicts the general annual trend of the generated thermal energy.

Recent advancements in hole transport layer (HTL)-free, printable carbon-based perovskite solar cells (C-PSCs) have gained increased research interest. Notably, their scalability, cost-effectiveness, and improved stability make them particularly attractive among various perovskite solar cell configurations. In the current study, we explored the potential of un-encapsulated, HTL-free, C-PSCs in outdoor and indoor light conditions, employing different concentrations of tin oxide (SnO₂) as the electron transport material. Among the investigated concentrations, 0.07 M SnO₂ precursor yielded the highest power conversion efficiency (PCE), reaching 9.79% under standard 1 sun illumination and 10.40% at a lower intensity of 0.6 sun. The PSCs demonstrated a remarkable 22.37% efficiency under 1000 lx indoor CFL illumination, and attained 22.21% efficiency under LED illumination, marking the highest reported indoor photovoltaic performance for carbon-based, HTL-free PSCs. To elucidate the underlying charge-transfer process, we carried out intensity-dependent current−voltage (J-V) measurements to analyze non-radiative bulk recombination in the perovskite layer. Interfacial recombination was investigated using electrochemical impedance spectroscopy (EIS) and transient photovoltage decay measurements. Optical and electrical stimulation of C-PSCs were performed under both full sun and indoor illumination, providing insight into recombination and light absorption differences under these illuminations. Additionally, we also showcased the potential of simple, printable indoor light harvesters for self-powered applications by connecting two C-PSCs to create a self-powered temperature sensor.

With the global population expected to reach 11 billion by the end of this century, the imperative of enhancing crop productivity per unit of land while conserving resources is paramount. This paper presents a novel approach to achieving these goals through Extended PAR-based photosynthesis (EPBP) methodology, specifically tailored for standalone Photovoltaic Greenhouses (PVGHs). By leveraging LED technology and extending photosynthesis during dusk and dawn periods, this methodology aims to enhance crop yield without substantial additional infrastructure investment. A comprehensive real-field experiment, conducted over a complete tomato crop cycle of 96 days, demonstrates a significant increase in crop yield, with a 51.29 % improvement compared to conventional PVGH without additional photosynthesis. Through meticulous analysis of key performance indicators such as leaf area index, specific leaf area, and dry matter weight, this study substantiates the efficacy of EPBP in optimizing crop growth within PVGHs. Further, the ROI of 14.11 % and 12.54 % have been observed for tomato crop grown with and without EPBP under the PVGH environment. It not only reduces crop growth period but also enhances both quality and yield quantity without additional operational expenses. The scope of the presented work is limited to the quantitative measurement; however, its impact on the quality of the crop yield could be further explored.

Fielded photovoltaic (PV) modules often exhibit series resistance-related defects, mainly due to solder bond degradation and metallization corrosion. To quantitatively analyze the series resistance increase in fielded modules, we conducted a detailed investigation on two sets of modules, employing two complementary techniques, electroluminescence (EL) and infrared (IR) imaging. The dependence of EL image characteristics on module temperature, as revealed in IR images, was a key focus of this study. The first and second sets of modules were exposed in Florida (hot and humid climate) and Arizona (hot and dry climate) over 10 years and 18 years, respectively. The resistive defect patterns obtained using EL and IR images showed a closer correlation for the Florida modules compared to the Arizona modules as the Florida modules primarily experience solder bond degradation. EL and IR images were acquired at five current injection levels (i.e., 0.1, 0.3, 0.5, 0.7, 1.0 x short circuit current) and two exposure times (i.e., 60 s and 300 s) and used to develop and report a new curve fitting method for estimating the external series resistance. The results indicate that inaccurate temperature determinations from IR images can lead to underestimations (up to 23 %) in EL-based external series resistance estimates. For the most accurate series resistance estimation, especially in modules with severe thermal defects and series resistance deterioration, the study recommends obtaining EL and IR images within 60 s of the current injection time. This study also reports a Monte Carlo simulation assessing the impact of EL and IR characteristics on the accuracy of external series resistance estimations.

In the operation of photovoltaic (PV) power plants, infrared cameras are commonly utilized for monitoring the operational status of PV modules. This study focuses on the performance improvement and complexity reduction of convolutional neural network (CNN) when used for fault classification based on infrared images of PV module. By implementing the transfer learning strategy on some famous CNN models, it is observed that the number of convolutional layers has weak impact on the classification results. Therefore, a transfer-learning-based depth reduction approach for CNN models (TLDR-CNN approach) is proposed, and the VGG16 model is employed for verification. Then, a multi-scale feature extraction module (MSFE module) is developed for efficiently replacing the convolutional layers to reduce model complexity and improve classification performance, and several representative model configurations are employed for convolutional layer replacement. Experimental results demonstrate that the application of the developed MSFE module significantly outperforms the baseline model on both classification performance and model complexity. Specifically, the modified model with a reduction of 5 convolutional layers exhibits notable improvements over the training results, with an accuracy increase of 0.90%, precision increase of 0.98%, F1 score increase of 6.89%, and a Matthews correlation coefficient increase of 1.01%. Finally, the interpretability of the above outperformance is also provided by using the Grad-CAM method. The generated CAM images show that the modified model concentrates its weights more on the regions crucial for the model to learn, so the features can be extracted more efficiently.

Thermionic conversion, due to its simple solid-state structure capable of converting heat to electricity directly, is promising for concentrated solar power. However, because of the extremely high cathode temperature, a large portion of the heat is lost to the environment. The paper introduces a novel concept of selective thermoradiative-graphene thermionic conversion (STR-GTI) that involving a combined control of photon and electron emission to modify the radiation dissipation. A detailed thermodynamic model is developed to evaluate the energy transfer irreversibility of STR-GTI solar conversion. The results demonstrate that the selective themoradiative photon emission and graphene thermionic electron emission effects synergistically reduce internal irreversible losses in the STR-GTI system, leading to a maximum energy efficiency of 34.34 % at a concentration ratio of 425, cathode work function of 1.8 eV and thermoradiative bandgap of 0.2 eV. The STR-GTI system outperforms both individual GTI and STR converters in terms of exergy efficiency and entropy production minimization. It exhibits a remarkable 102.03 % increase in exergy efficiency compared to the STR & GTI system at a thermoradiative voltage of −0.14 eV, accompanied by a 28.56 % reduction in exergy loss and a 37.83 % decrease in entropy production. The combination of narrowing the spectral radiation bandwidth and significant electron emission capabilities of graphene contribute to the system’s resilience against solar radiation fluctuations.

This research presents an innovative approach for developing a flexible wood sponge (WS) with a hierarchically porous structure. This unique structure is achieved through a sequential process involving balsa wood delignification, freeze-drying, and subsequent coating with graphene flake (GF)/polyaniline (PANI) nanocomposite. The resulting GF/PANI nanocomposite significantly reduces electron transfer resistivity, thereby enhancing heat generation for water evaporation. This results in self-cleaning photoabsorber, benefiting from GF’s salt-rejecting properties, PANI’s ionic network, and the WS’s porous structure. The photoabsorber demonstrates improved mechanical strength, reduced thermal conductivity, and a single water route design atop a drilled insulator foam, effectively minimizing heat loss during solar desalination. Under 1 sun (1 sun = 1 kW m⁻²) illumination, the photoabsorber achieves an impressive evaporation flux of 1.49 kg m⁻²h⁻¹ and a high solar to thermal efficiency of 95.51 %. Importantly, continuous 10-cycle testing under 1 sun illumination reveals no salt deposition on the surface. Furthermore, the photoabsorber demonstrates promising applications in wastewater treatment, effectively purifying dye-contaminated seawater and desalinating both acidic and alkaline seawater. The investigation into the GF/PANI nanocomposite’s effect on steam generation, conducted through electrochemical impedance spectroscopy in a 0.5 M Na₂SO₄ electrolyte, reveals enhanced interfacial charge transfer, surpassing both PANI and GF due to reduced electrochemical resistance. Evaluation of desalinated seawater and purified wastewater demonstrates a significant decrease in major cation concentrations, meeting WHO and EPA drinking water standards. These findings underscore the potential of the GF/PANI nanocomposite in superior steam generation applications.

Despite their high efficiency, perovskite solar cells encounter stability issues and necessitate techniques capable of depositing large areas at a high throughput of their layers. Niobium pentoxide exhibits pertinent characteristics, including suitable energy level alignment and photostability for effective integration as transport layer in perovskite solar cells, improving their stability. In this study, the deposition of Nb₂O₅ as an electron transport layer via slot die coating is systematically investigated. An examination of various parameters for the slot die coating process was conducted, resulting in films with different structural and morphological characteristics. These Nb₂O₅ layers were used as electron transport layers in n-i-p perovskite devices. Current density versus voltage scans were utilized to evaluate the device performance, alongside transient analysis. Under optimal coating conditions, efficiencies up to 12 % were obtained. A transient analysis at the maximum power point identified an optimal delay time of approximately 200 ms for integration into the current–voltage curves, facilitating the approach towards an equilibrium state within the device. A discussion regarding the transient response is presented, delving into the factors that restrict the device’s performance and proposing potential strategies for its enhancement.

The fabrication of a counter electrode possessing elevated catalytic efficiency and steadfast stability is a crucial prerequisite for the high-performance quantum dot sensitized solar cells (QDSCs). Mesoporous carbon (MC) has been adopted as the desired CE material in the past years, but the disadvantage of its poor conductivity has limited further development of the performance of QDSCs. In this study, we present a straightforward approach for producing highly effective counter electrodes through the integration of nitrogen-doped mesoporous carbon (N-MC) with carbon nanotubes (CNTs), forming a composite material that is deposited onto a titanium mesh substrate. The counter electrode (CE) based on composite materials shows excellent electrocatalytic performance, synergistically benefiting from large specific areas of N-MC and high conductivity of CNTs. Electrochemical measurements reveal that the optimal CEs exhibit excellent catalytic reduction activity as well as high electron mobility. Consequently, the corresponding QDSCs show a record power conversion efficiency of 16.68 %.

Cu₂BaSn(S,Se)₄ (CBTSSe) solar cells, are an intriguing kind of photovoltaic devices with theoretical efficiency close to 31 %. Their promise in the field of renewable energy is highlighted by their sustainable structure, as well as their low density of defects. Even with these benefits, the record efficiency for CBTSSe solar cells is now only 5.2 %. In order to identify limitations in performance and clear the path for obtaining improved practical efficiency, this emphasizes the vital requirement for deep analysis. In this work, we investigate a new structure based on Cd free In₂S₃/CBTSSe heterojunction in which an Indium (III) sulfide as ETL layer, and CBTSSe as absorber layer take the place of the traditional CdS/ CBTSSe structure. For the first time, an analytical model that incorporates a variety of recombination mechanisms occurred in CBTSSe solar cell, such as Auger, Shockley-Read-Hall (SRH), interface recombination, tunneling-enhanced recombination, and non-radiative recombinations is proposed. In our approach the reverse saturation mechanism is taken into account in the suggested model as a metric to identify the main recombination mechanism. Significantly, there is a good agreement between the outcomes of our model and the experiment. It is shown that CBTSSe bulk recombination, In₂S₃/CBTSSe interface recombination and resistances are dominating. Besides, the developed model serves as fitness function for MOGA approach to locate the optimal parameters design combination that led to optimal efficiency. We demonstrate the ability to obtain an efficiency of up to 10.12 % by carefully tuning both the CBTSSe bulk material parameters and the In₂S₃/CBTSSe interface features. Our findings demonstrate that the optimized design using In₂S₃/CBTSSe heterojunction outperforms the baseline, reaching a high J_SC of 20.57 mA/cm², V_OC of 0.88 V, and FF of 55.54 %, with appropriate band alignment at the In₂S₃/CBTSSe interface and optimized physical and geometrical parameters. The suggested approach paves the way for additional design optimization while also making it possible to identify the degradation factors that are responsible.