This study presents the design and techno‑economic feasibility of a grid‑connected photovoltaic (PV) system for a university’s central building in Iran, in response to a national mandate requiring executive bodies to supply 20% of their electricity consumption from renewable sources by 2027. The system is sized using actual monthly electricity consumption data and local solar resource assessments, resulting in a 302 kWp plant with 432 bifacial panels and three 100 kW inverters. Two installation scenarios—rooftop and ground‑mounted—are evaluated using PVsyst and DesignBuilder simulations. A novel aspect is using penalty rates from Green Board of the Iran Energy Exchange, rather than fixed feed‑in tariffs, for economic assessment. The system generates 520.45 MWh annually, with a performance ratio of 82.2% and a capacity factor of 19.7%. The rooftop scenario reduces roof heat gain by 22.1%, lowering cooling demand by 12.24 tons of refrigeration. Economic analysis reveals a payback period of 5.8 years and an LCOE of 0.0524 USD/kWh. The project also achieves a 95.4% reduction in CO₂ emissions compared to grid electricity. At the national level, it saves 109,338 m³ of natural gas annually, with an export value of €32,801 and an opportunity cost of $42,156 for the exported electricity, demonstrating that rooftop PV systems offer both local and national economic and environmental benefits.
Photovoltaic (PV) and PV–thermal (PV/T) systems are increasingly important for sustainable energy generation. However, elevated operating temperatures reduce PV electrical efficiency and affect the thermal and overall performance of these systems. Effective thermal management is therefore essential for improving electrical output in PV systems while simultaneously enhancing heat recovery in PV/T systems. This review critically examines recent developments in nanofluid-assisted cooling for PV and PV/T systems, focusing on thermal, electrical, hydraulic, thermodynamic, and techno-economic performance, as well as nanofluid stability and emerging computational technologies. Various cooling configurations, including backside cooling plates, mini- and microchannels, jet-impingement systems, heat pipes, and advanced PV/T collectors, are discussed. Recent developments involving metal oxides, carbon-based nanomaterials, MXene, hybrid, and ternary nanofluids are critically reviewed. The literature indicates that nanofluids reduce PV/PV/T operating temperatures, improve electrical efficiency, enhance useful thermal energy recovery, and improve energy and exergy performance when nanoparticle characteristics, cooling configurations, and operating conditions are properly optimized. However, these benefits may be accompanied by increased viscosity, pressure drop, pumping power, and stability-related problems. Particular attention is therefore given to nanoparticle agglomeration, sedimentation, fouling, and long-term reliability. Recent applications of computational fluid dynamics, artificial intelligence, machine learning, and optimization techniques are also examined. Although significant improvements have been reported, long-term outdoor validation, standardized testing, and comprehensive economic and environmental assessments remain limited. Future development should focus on stable, low-cost, environmentally responsible, and scalable nanofluid-based cooling technologies for practical PV and PV/T applications.
This study examines the reliability and maintenance of solar photovoltaic (PV) systems in Lango, Uganda, using a descriptive survey of 280 respondents, site observations, Failure Modes and Effects Analysis (FMEA), and exponential reliability modelling. Aggregate reported-event counts were 460 for solar panels, 965 for batteries, 690 for inverters, and 310 for charge controllers. Using a nominal exposure of 102,200 component-days per class, estimated event rates were 0.004501, 0.009442, 0.006751 and 0.003033 day⁻¹, respectively, with corresponding 95% Poisson/chi-square confidence intervals of 0.004099–0.004932, 0.008856–0.010057, 0.006257–0.007275 and 0.002705–0.003390 day⁻¹. Under an independent exponential series model, calculated system reliability was 1.40% at 180 days and 0.01733% at 365 days. These estimates are conditional on nominal exposure and unverified classification of reported events as functional failures. An analytical cost and availability model compares corrective, age-based, and grouped maintenance policies. The constant-hazard model predicts no preventive-maintenance reliability gain; an optimal interval requires intervention costs, outage durations, and measured maintenance effects. The findings identify priorities for validating operational records and developing component-specific maintenance policies.
Thorium-based compounds are considered promising fuel materials for advanced nuclear reactors. The aim of this work is to study the structural, electronic, phonon, bonding, mechanical, thermophysical, and radiation damage properties of ThX (X = C, N, P, As, Sb, O, S, Se) compounds and to find the most suitable compound for high-temperature nuclear applications. The optimized lattice parameters agree well with available experimental and theoretical data, and the negative formation energies show that all compounds are thermodynamically stable. Electronic band structure and density of states analyses reveal metallic behavior across the series. The phonon dispersion curves confirm the dynamical stability of ThC, ThN, ThP, ThO, and ThS. Furthermore, bond population and charge density analyses indicate mixed ionic–covalent bonding, with covalent character most pronounced in ThC. Elastic constants satisfy the Born stability criteria, with all compounds except ThC (borderline) exhibiting ductile behavior. For the first time, the lattice thermal conductivity (using Slack’s equation) and diffusion thermal conductivity of the compounds have been evaluated. Thermophysical assessments identify ThN as the most promising candidate for high-temperature energy applications, exhibiting the highest Debye temperature (389.5 K), melting point (~2919 K), and lattice thermal conductivity (18.38 W m⁻¹ K⁻¹ at 300 K), alongside minimal thermal expansion. IRAD-based radiation damage analysis revealed that ThC and ThN show the deepest hydrogen penetration (~0.055 cm), with a maximum hydrogen concentration of ~ 0.015% and maximum damage of ~0.0015 dpa, and their defects are more uniformly distributed. Based on these results, ThN is found to be the most suitable compound among the studied ThX series for nuclear fuel applications, followed by ThC.
Coal-fired thermoelectric plants remain important for dispatchable electricity generation and supply stability, but their dependence on fossil carbon results in high greenhouse gas emissions. This study evaluated pilot-scale batch pyrolysis of green coconut husk pellets for biochar production and its incorporation into bituminous coal blends as a potential route for partial fossil-coal substitution. Pyrolysis experiments were performed in a pilot-scale pyrolysis unit using 40 kg of pellets at final temperatures of 400 and 500 °C. The products were characterized by proximate analysis, higher heating value (HHV), non-condensable gas composition, and mass and energy balances. Coal–BIO400 blends were prepared with biochar produced at 400 °C (BIO400) at 1, 5, 10, and 20 wt% and characterized for proximate, elemental, inorganic, morphological, surface elemental, and energetic properties. Pyrolysis at 400 °C favored biochar production, with a yield of 34.13%, compared with 28.05% at 500 °C. Although the 500 °C condition increased non-condensable gas yield from 15.93% to 22.57%, the 400 °C condition showed a significantly higher recoverable product-energy ratio, while no statistically significant differences were detected in gross product-energy recovery ratio or biochar energy between the two conditions. BIO400 showed low moisture content, high fixed carbon content, and an HHV of 27.42 MJ·kg⁻¹, corresponding to 96.7% of the bituminous coal HHV. The coal–BIO400 blends retained HHV values of 28.25–28.44 MJ·kg⁻¹, and no statistically significant differences in HHV were detected among BIO400, bituminous coal, and the coal–BIO400 blends under the reported analytical conditions. These results support the evaluation of green coconut husk biochar as a potential component for partial fossil-coal substitution, although combustion, emission, ash behavior, boiler compatibility, and life-cycle assessments are still required.
