Search Results (1,608)

Evacuated-tube solar collectors charged with hybrid nanofluids can raise thermal output, but their coupled thermal and hydraulic response depends on many interacting variables, making the design an optimisation rather than a prediction problem. This study recasts it as a constrained, mixed-variable, three-objective task that maximises thermal efficiency and the Nusselt number while minimising pumping power over the hybrid pair, base fluid, weight fraction, component-one share and flow rate, and develops a memetic metaheuristic: the Adaptive Memetic Hybrid (AMH). A histogram gradient-boosted surrogate trained on 54,432 reduced-order runs, with held-out coefficients of determination of at least 0.9999, provides a fast screen, while a continuous reduced-order model validated to within 0.02 percent serves as the objective; the surrogate is accurate off-grid for efficiency but not for pumping power or the Nusselt number. Nine optimisers, comprising four baselines, three recent metaheuristics, and two AMH variants, were validated on twelve ZDT, DTLZ, and constrained problems over thirty trials using the hypervolume, generational distances, and spacing, and analysed with Friedman, Nemenyi, and Holm-corrected Wilcoxon tests. AMH attained the best mean Friedman rank of 3.08 (chi-square 65.7, p = 3.6 × 10⁻¹¹), significantly outperforming the recent methods and NSGA-III and remaining competitive with the strongest classical algorithms. On the collector, the reduced-order front recovers the 1512-design brute-force maximum efficiency to within 0.02 percent and improves the trade-off through continuous flow rates. The study is a deterministic, model-based optimisation process: the surrogate serves as a tool for fast screening and diagnostics, while the reconstructed reduced-order model is the objective for the final continuous optimisation. The collector application has a low effective design dimension, being governed mainly by the base fluid and the loop flow rate, so the decisive separation of the algorithms is established on the benchmark suite rather than on the collector. Experimental validation remains a task for future work. Full article

In this work, Cu₂CoSnS₄ (CCTS) thin films were deposited on glass substrates by thermal evaporation and investigated for photovoltaic applications. The influence of substrate temperature, varied from 25 °C to 200 °C, on the structural, morphological, and optical properties of the films was experimentally studied using X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) measurements. XRD analysis confirmed the formation of crystalline CCTS with a stannite structure and a preferential orientation along the (112) plane. SEM observations revealed rough and non-uniform surfaces accompanied by an increase in grain size with increasing substrate temperature. Room-temperature PL measurements indicated a band-gap energy of approximately 1.3 eV, suitable for photovoltaic applications, and confirmed the presence of secondary phases in the p-type stannite CCTS films. Despite the promising photovoltaic properties of CCTS, numerical studies on CCTS-based solar cells remain scarce in the literature. In this context, a numerical study of the CCTS-based solar structure grown on glass was also performed using SCAPS-1D, showing good agreement with experimental photovoltaic results and validating the simulation model. Replacing the glass substrate with silicon improved the device efficiency to 5.77%. Further optimization of the series and shunt resistances significantly enhanced the photovoltaic performance, achieving a power conversion efficiency of 16.77%, with FF = 52.94%, V_oc = 0.89 V and J_sc = 35.19 mA/cm². Full article

Fresnel high-concentration photovoltaic/thermal (HCPV/T) systems operating in sandy environments are susceptible to natural lens soiling, which attenuates the effective concentrated solar input and alters electrical and thermal performance. Natural-soiling comparison tests were conducted over 0–28 d, and an SD-CNN-BiLSTM-Attention model was developed to forecast cell-center temperature and electrical power 5, 10, and 20 min ahead. At a surface soiling density of 10.760 g·m⁻², current and electrical power decreased by 38.37% and 39.28%, respectively, relative to the concurrently operated clean-reference unit; cell-center temperature and water-tank temperature rise decreased by 7.74% and 15.13%. Thermal power also showed an overall downward trend, although the magnitude was affected by relatively large measurement uncertainty. Under grouped cross-validation, temperature RMSEs were 0.473, 0.515, and 0.555 °C at 5, 10, and 20 min, corresponding to reductions of 8.34%, 21.68%, and 44.07% relative to Persistence. Electrical-power RMSEs were 0.661, 0.618, and 0.640 W, with an 18.24% reduction relative to Persistence at 20 min. Ablation analysis showed a limited contribution from surface soiling density at 5 and 10 min but a clearer contribution at 20 min. These results support electrical and thermal performance assessment and short-term operational forecasting of Fresnel HCPV/T systems in sandy environments. Full article

Photovoltaic converters operate under varying climatic conditions and non-ideal grid regimes, but factor importance is often assessed either through isolated local metrics or through pooled operating data that hide regime shifts and interaction effects. This study develops a hierarchical framework for sensitivity analysis of operating profiles of grid-connected PV converters under climatic and grid uncertainty. A compact operating-profile formulation is introduced that relates solar radiation, cell and ambient temperature, grid voltage, load, and selected design/control parameters to active power, efficiency, power factor, harmonic distortion, DC bus ripple, clipping behavior, and thermal headroom. The proposed workflow combines local normalized sensitivities for fast ranking around nominal conditions, Morris screening for factor reduction, and Sobol/Saltelli variance-based indices for global prioritization under uncertainty. The framework is demonstrated on a 100 kW synthetic reduced-order benchmark representing a three-phase two-level grid-connected PV inverter with an LCL filter. To clarify the scope of validity, the reduced-order model is cross-checked against switching-level simulations for representative nominal, clipping-prone, high-temperature and grid-stress operating windows. The results show that factor importance is not universal, but depends on the selected KPI, operating regime and uncertainty scenario. In the considered benchmark, grid voltage, cell temperature and equivalent thermal resistance are the dominant total-effect contributors, while the strongest second-order contribution appears between grid voltage and filter inductance under grid-stress conditions. The proposed framework is therefore intended as a reproducible, regime-aware sensitivity workflow rather than as a universal ranking of PV converter parameters. Full article

Hybrid solar–thermal energy harvesting systems are an important advancement in renewable energy technology, enabling simultaneous production of electrical power and useful thermal energy within a single compact platform. However, their performance is often limited by poor heat transfer and inefficient mass transport of working fluids, leading to photovoltaic thermal degradation and significant exergy losses. This study aims to optimize heat and mass transport processes in a hybrid solar–thermal mechanical system to enhance energy recovery and ensure long-term operational reliability. A three-dimensional numerical model based on the finite volume method (FVM) was developed using the governing equations of continuity, momentum, and energy conservation. A Multi-Objective Genetic Algorithm (MOGA) was employed to determine optimal microchannel geometries by analyzing variable cross-section effects on flow behavior and thermal boundary layer disruption. At the Reynolds number of 2000, the optimized configuration increases the average Nusselt number by 43.5% compared to a smooth channel. Consequently, the photovoltaic operating temperature decreases by 12.6 °C, improving electrical efficiency by 9.3%. The system achieves a maximum thermal efficiency and net energy gain of 76.8%, while maintaining an acceptable 16.3% increase in pumping power. The results confirm that optimizing mass transport is essential for effective thermal regulation and improved energy conversion performance, providing a strong foundation for high-efficiency solar collector design. Full article

Large-scale renewable energy bases with high penetration of renewable energy are facing increasing challenges related to renewable energy curtailment. Concentrated solar power plants with thermal energy storage can provide dispatchable power output, while electric heaters offer a promising pathway for converting surplus renewable electricity into useful thermal energy. In this study, a photovoltaic–wind turbine–electric heater–concentrated solar power integrated energy system with a fixed CSP-EH configuration is investigated. The electric heater is introduced as the key electrical-thermal coupling device, which recovers otherwise curtailed photovoltaic and wind power and injects the converted thermal energy into the heat transfer fluid loop of the concentrated solar power plant. A mixed-integer linear programming model is developed to optimize the coordinated scheduling and evaluate different PV/wind capacity mixes under fixed CSP and electric-heater capacities. Results show that, under the fixed capacities of 100 MW concentrated solar power and 150 MW electric heater, the PV/wind capacity mix of 500 MW photovoltaic and 400 MW wind power achieves the best overall performance among the studied cases. Under different typical-day conditions, the electric heater recovers surplus renewable electricity, with recovery rates ranging from 16.06% to 20.21%. The proposed electric heater–concentrated solar power coupling mechanism transforms curtailed renewable electricity into dispatchable thermal energy, thereby reducing renewable energy curtailment, enhancing thermal-side flexibility, and improving the operating revenue of large-scale renewable energy bases under the studied PV/wind capacity-mix scenarios. Full article

While Thermal Infrared (TIR) sensors are standard for monitoring volcanic activity, their efficacy is severely compromised by meteorological clouds and dense volcanic ash. To overcome these optical limitations, we present the first ground-based application of a passive microwave radiometer for continuous volcano monitoring. Operating in the 10–12 GHz band, our Total Power Microwave Receiver is stationed 12 km from Mount Etna’s active craters to measure thermal emissions from eruptive hotspots. Unlike traditional TIR imaging, this low-cost, automated system exploits the atmospheric transparency of microwave wavelengths, enabling uninterrupted observation regardless of weather or solar illumination. We detail the system’s design and report its successful detection of volcanic phenomena during the 2023–2025 eruptive cycles, including the transit of a high-temperature ash cloud that triggered a significant radiometric peak. Our findings demonstrate that fixed-point microwave radiometry provides a reliable thermal signature of eruptive activity, offering a pioneering and highly accessible tool for the next generation of global volcanic early warning systems. Full article

This study directly compares a photovoltaic (PV)-powered vapor-compression chiller with a solar-thermal-driven absorption chiller for localized cooling of the tomato crop zone in a 1536 m² smart greenhouse under a hot-arid climate. The principal contribution is a controlled system-level comparison of two solar-cooling pathways under the same greenhouse load, solar-aperture area, terminal equipment, rated cooling capacity, and crop-zone temperature-control constraints. The previously validated greenhouse model was transitioned from EnergyPlus 8.9 to Version 23.1, after which the two alternative plants were connected to the same base model. Base-case annual simulations produced nearly identical chiller cooling energy (1669.3 and 1668.9 MWh) and was only 4 and 5 h above 28 °C. The PV-powered system required 101.6 MWh of net grid electricity, whereas the absorption system used 202.3 MWh of electricity and 253.2 MWh of natural gas and achieved an 84.23% solar fraction. Static operational primary energy was 331.2 and 912.7 MWhPE, respectively; HSDH28 was 0.50 and 0.81 °C·h; and peak grid import was 113.46 and 63.61 kW. The absorption case additionally required 10,103.6 m³/yr of cooling-tower makeup water. Storage/EMS sensitivity changed the absorption solar fraction from 58.17% to 88.30% and natural-gas use from 187.7 to 674.0 MWh/yr without materially changing cooling service. Matched 50–100 W/m² daytime latent-load sensitivity increased annual cooling by 14.7–28.8%. At the 100 W/m² bound, HSDH28 increased to 49.32 °C·h for PV and 8.06 °C·h for absorption, while the principal energy–infrastructure trade-off remained: static primary energy was 712.4 versus 1354.2 MWhPE and peak grid import was 137.46 versus 63.96 kW. A bounded hourly primary-energy-factor stress test did not reverse the technology ranking, and balanced TOPSIS scores were 0.766 for PV and 0.234 for absorption. The results show that PV vapor compression minimizes operational primary energy and cooling-water use, whereas solar-thermal absorption reduces electrical peak demand and shows greater thermal-control resilience at the highest tested latent-load bound. Full article

This paper presents a detailed analysis of the operating parameters of a solar active installation with seven photovoltaic-thermal (PV/T) collectors with a total area of 14 m² in a single-family house. A comparative analysis of the work parameters was carried out for the following two locations: Warsaw (Poland) and Andravida (Greece), based on the research of the solar system model created in the TRNSYS 16 program. Considering the months with the best sunshine, from May to August, the average monthly electricity yield in PV/T solar collectors was 206 kWh (Warsaw) and 248 kWh (Andravida). In July, the monthly generation-to-consumption ratio of the PV/T system under the Polish climate conditions was 82%, and under the Greek climate conditions—99%. The heat recovery from PV/T solar collectors in July in the climate of Greece was estimated at 264 kWh and is 29% higher compared to the heat recovery in a hybrid solar installation located in Poland. The generation of electricity in the PV/T solar system instead of a coal-fired power plant can contribute to the avoidance of the annual emissions of pollutants by: 14.00–19.11 kg of SO₂, 2.72–3.72 kg of NO_X, 5.44–7.43 kg of CO, 1330.86–1816.79 kg of CO₂, and 1.09–1.49 kg of particulate matter, depending on the location. Full article

The development of indoor photovoltaic devices for powering Internet of Things (IoT) sensors requires low-cost and sustainable components, making dye-sensitized solar cells (DSSCs) an ideal candidate for artificial light harvesting. The counter electrode plays a critical role in transferring electrons and catalyzing the reduction in the redox electrolyte. However, the traditional use of expensive and scarce platinum (Pt) limits the cost-effective, large-scale commercialization of these devices. While carbon-based materials offer a highly porous, conductive, and abundant alternative, commercial carbon pastes frequently require energy-intensive high-temperature sintering. In this study, we propose a sustainable, low-temperature, and screen-printable carbon composite counter electrode (LoT-HPC) using bio-derived hydroxypropyl cellulose (HPC) as a highly effective binder. Rheological characterizations confirm that the formulated LoT-HPC ink possesses an ideal shear-thinning profile and rapid structural recovery, ensuring excellent printability and film homogeneity. By comparing the custom LoT-HPC composite against a commercial high-temperature screen-printed graphite paste (HT-Elco) and a standard sputtered Pt-FTO electrode, we demonstrate the structural and electrocatalytic advantages of this material. When integrated into full DSSC devices and evaluated under low indoor illumination (1000 lux), the LoT-HPC cell delivers a power conversion efficiency (PCE) of 14.8% and a high short-circuit current density of 103.9 µA cm⁻². Furthermore, the custom device demonstrated exceptional operational stability, retaining 98.6% of its initial efficiency (from 14.8% to 14.6%) after 200 h of continuous light-soaking and J-V cycling under 1000 lux. Ultimately, the successful implementation of the HPC binder enables the low-temperature fabrication of sustainable carbon counter electrodes without the need for energy-intensive thermal treatments, presenting a highly scalable pathway for indoor DSSC manufacturing. Full article

The rise in the need for sustainable energy has facilitated the advancement of perovskite solar cells (PSCs) as potential substitutes for traditional photovoltaic technologies. Nevertheless, their performance is very sensitive to environmental factors, especially temperature, which influences the charge transport and recombination processes. This paper examines the thermal effect on the electrical characteristics and impedance response of lead-free PSCs in accordance with the FTO/ETL (C₆₀, PCBM, SnS₂, ZnSe)/CH₃NH₃SnBr₃/Cu₂O configuration. The experiments were performed with SCAPS-1D under usual illumination, using a combination of current-voltage analysis and impedance spectroscopy between 270 and 400 K. The findings indicate that there is a significant reduction in open-circuit voltage with higher temperature, whereas the short-circuit current density does not change much. The enhancement of the fill factor increases and then decreases with increased temperature, leading to a net decrease in power conversion efficiency because of the increased recombination. The impedance analysis is also an indicator of lower recombination resistance and accelerated charge carrier dynamics. These results demonstrate that thermal control and interface optimization can be important for enhancing PSC performance. Full article

Cold-climate dwellings can face coincident electricity and domestic hot-water shortfalls in winter, when solar availability is at its lowest. This study evaluates an integrated residential system for Aomori, Japan, combining photovoltaics, evacuated-tube solar water heating, and battery storage with electrolysis, compressed-hydrogen storage, and a PEM fuel cell operated in combined-heat-and-power mode. Building on a screening-level annual-balance analysis, a coupled annual TRNSYS simulation with a 0.125 h time step resolved battery dispatch, electrolyzer part-load operation, hydrogen compression and finite storage, seasonal fuel-cell operation, and heat recovery. The results show that the principal value of seasonal hydrogen lies in improving winter supply adequacy, dispatchability, and heat recovery rather than annual conversion efficiency. Fuel-cell heat recovery increased the number of days satisfying the hot-water screening indicator—a daily mean tank temperature of at least 43 °C—from 221 to 332. A reserve-aware criterion identified a 225 W electrolyzer operating-power cap as the positive-reserve case; 205 W was near-cyclic with a negligible margin, whereas the original 475 W cap was substantially oversized. The hydrogen pathway remained markedly less efficient than direct photovoltaic and solar-thermal use, and the estimated storage hardware’s lower bound substantially exceeded the break-even capital ceiling supported by the annual operating value. Seasonal hydrogen can therefore strengthen winter energy adequacy and heat recovery but is not yet cost-effective at the single-dwelling scale under the investigated conditions. Full article

Satellite battery subsystems are fundamental for reliable operation during periods when solar power is unavailable. Their performance is strongly influenced by the harsh and variable thermal conditions of the space environment. Pre-launch thermal simulations are routinely employed to evaluate subsystem behaviour; however, their ability to fully represent in-orbit dynamics remains limited. Meanwhile, machine learning (ML) approaches have emerged for satellite health monitoring, yet their practical role alongside conventional thermal analysis is not clearly established. This study investigates satellite battery temperature prediction by integrating pre-launch thermal simulation, real in-orbit telemetry, and data-driven ML forecasting within a unified framework. A dataset of 27,552 temperature measurements from an operational low-Earth-orbit satellite was analysed. A sliding-window regression approach was used to predict one-hour-ahead minimum and maximum battery temperatures, consistent with operational thermal margins. Three models—linear regression, Random Forest, and Extreme Gradient Boosting—were trained using historical temperature data and evaluated against telemetry and simulation outputs using MAE, RMSE, and R² metrics. Results indicate that linear regression achieved the highest accuracy (R² up to 0.98, MAE ≈ 0.20 °C), outperforming more complex models. ML-based predictions captured thermal behaviour more effectively than static simulation outputs under nominal conditions, while all predicted values remained within the acceptable operational range (10–30 °C). Rather than replacing physics-based methods, this work demonstrates that interpretable ML models can serve as an effective real-time complement to thermal simulations, offering practical insights into model selection and enhancing satellite battery thermal monitoring. Full article

Hybridizing concentrated solar power (CSP) with residual biomass allows supercritical CO₂ (sCO₂) power cycles to deliver dispatchable low-carbon electricity, but it is unclear whether the extra equipment of the more efficient layouts adds a life-cycle burden that offsets their thermodynamic gain. This work reports what is, to the authors’ knowledge, the first unified energy, exergy, environmental and exergoenvironmental comparison of two combined sCO₂–organic Rankine cycle (ORC) configurations—a simple and a recompression Brayton layout, both with reheating, regeneration and a toluene bottoming ORC—driven by a solar tower and a coconut-shell-biomass furnace. Life-cycle impacts are quantified with Eco-indicator 99, a damage-oriented method that scores construction, operation and decommissioning damage in milli-points (mPts), and are allocated to the exergy streams through the exergoenvironmental balance. Both cycles are modelled in Python with CoolProp properties and validated against published sCO₂ analyses (efficiency deviation below 7.3%). The recompression layout reaches 54.3% thermal and 32.0% second-law efficiency and cuts the exergy destruction from 173 to 128 kW. Its larger construction impact (22.6 vs. 20.1 mPts/h) is negligible against the shared biomass reheater (429.4 mPts/h), so it is also marginally cleaner overall (459 vs. 472 mPts/h). Efficiency-oriented layout selection is therefore environmentally safe, and the remaining leverage lies in the biomass supply chain. Full article

Decarbonizing the process heat required for chemical recycling would improve the environmental performance of plastic-waste valorization. This study presents an evaluation of the use of concentrated solar thermal energy as the reaction heat source for the hydrothermal depolymerization of post-consumer polyethylene terephthalate (PET). The solar-driven hydrothermal process (HTP-S) maintained an internal reactor temperature of approximately 200 °C for 4 h under favorable irradiance conditions. During the single experimental run, the system received 14.95 MJ of incident solar energy, whereas the conventional hydrothermal process (HTP-C) consumed 47.52 MJ of electricity per run. Starting from 1.2 g of PET, HTP-C and HTP-S produced 0.862 and 0.895 g of dry recovered solid, corresponding to recovered-solid yields of 71.7% and 74.5%, respectively. Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis and derivative thermogravimetry (TGA/DTG), transmission electron microscopy (TEM), and X-ray diffraction (XRD) showed that the recovered solids exhibit physicochemical characteristics consistent with the formation of a crystalline terephthalic acid (TPA)-rich product. A cradle-to-gate life cycle assessment normalized to 1 kg of treated PET showed that cumulative energy demand decreased from 44,383.7 MJ for HTP-C to 7342.5 MJ for HTP-S, while global warming impacts decreased from 9717 to 1607 kg CO₂-eq. These results demonstrate the technical feasibility of coupling concentrated solar heating with hydrothermal PET depolymerization and identify reaction heating as the principal opportunity for reducing external electricity demand. These outcomes indicate that solar-powered hydrothermal processing provides a feasible pathway for PET recycling, reducing the environmental footprint. Full article