Search Results (320)

The integration of Concentrated Solar Power (CSP) and Photovoltaic (PV) technologies represents a promising strategy to enhance the reliability, flexibility, and dispatchability of solar-based electricity generation. The novelty of this work lies in the development and assessment of an integrated PV–CSP hybrid power plant in a series configuration, where the two technologies are energetically coupled and coordinated with thermal energy storage and an electrolyzer under a grid-minimization operating strategy. Unlike most previous studies, which investigate PV and CSP systems as standalone or loosely coupled technologies, the proposed approach simultaneously optimizes renewable electricity utilization, dispatchable operation, and green hydrogen production. A comprehensive simulation framework was developed using site-specific solar irradiance data, component performance models, thermal energy storage characteristics, and electrolyzer operating constraints. A seasonal operating strategy was adopted, with the CSP plant and the electrolyzer operating from 15 April to 15 October, while the PV system generated electricity throughout the entire year. Under these conditions, the electrolyzer operated for 4416 h·year⁻¹, producing 1000 t·year⁻¹ of green hydrogen and requiring an annual electricity demand of 52.4 GWh. The hybrid renewable system supplied 37.2 GWh of this demand, corresponding to a renewable penetration of approximately 71%, while the remaining 29% was covered by grid electricity purchases. Results show that the series hybridization of CSP and PV technologies improves overall plant performance compared with standalone solar systems. In particular, the integration of thermal energy storage within the CSP subsystem enabled dispatchable generation and more stable electrolyzer operation. All the electricity generated by the CSP plant was directly utilized by the electrolyzer, and approximately 17% of the renewable electricity supplied to the electrolyzer was delivered during periods when PV production was unavailable, corresponding to 12.2% of the total annual electricity demand of the electrolyzer. Furthermore, of the total annual PV generation of 33.6 GWh, 15.1 GWh were directly used for hydrogen production, while 18.5 GWh were exported to the electrical grid, resulting in a positive annual electricity balance. The analysis provides design and operational guidelines for optimizing integrated PV–CSP plants coupled with hydrogen production systems under a grid-minimization strategy. The findings confirm that hybrid solar systems integrating dispatchable CSP generation, thermal energy storage, and PV technologies can significantly increase renewable penetration, support stable, low-carbon power generation, and enable large-scale green hydrogen production with reduced dependence on grid-supplied electricity. Full article

Dye-sensitized solar cells (DSSCs), belonging to the third generation, are highlighted for their low production cost compared to other photovoltaic technologies. These cells are composed of a cathode, an electrolyte, and an anode, commonly using TiO₂. This work aims to produce and characterize CeO₂, SnO₂, and ZrO₂ oxides as substitutes for TiO₂ in DSSCs. The semiconductor oxides were synthesized using the Pechini methodology and applied as the anode of the system. The device was assembled in a sandwich configuration, with an anode and cathode (graphene), an active area of 0.2 cm², and an electrolyte containing the I₃⁻/3I⁻ redox pair. The techniques employed included scanning electron microscopy (SEM), dynamic light scattering (DLS), X-ray diffraction (XRD), UV-Vis spectroscopy, open-circuit potential curves and electrochemical impedance spectroscopy (EIS). The oxides exhibited good crystallization with non-defined morphology. The obtained band gap values were 2.8 eV, 3.0 eV, 3.1 eV, and 4.8 eV for CeO₂, TiO₂, SnO₂, and ZrO₂, respectively. In DSSCs, these oxides showed photosensitivity, generating potential when exposed to light with TiO₂-based cell exhibited the lowest charge transfer resistance (R_ct = 57.8 kΩ). This comparative framework establishes a preliminary screening of the intrinsic interfacial charge transfer and recombination kinetics of alternative standalone photoanodes, serving as a baseline for future device optimization. Full article

Renewable energy communities (RECs) are increasingly recognized as a strategic instrument for enhancing the sustainability and resilience of energy systems, promoting local renewable integration, and reducing consumer exposure to electricity market volatility. This study analyzes the Italian electricity market and assesses the economic performance of RECs relative to individual consumers using high-frequency hourly data from 2021 to 2023, covering both the 2022 European energy crisis and the subsequent Italian regulatory reform of incentive mechanisms. The optimization problem is formulated in physical terms, aiming to maximize locally utilized energy, defined as the sum of self-consumed and shared photovoltaic generation. This choice reflects the structure of the Italian regulatory framework, where incentives are directly linked to the amount of energy shared within the community. In this context, energy-based optimization is preferred to avoid embedding assumptions on discount rates, investment horizons, and financing conditions, which may vary significantly across users and introduce additional uncertainty. From a sustainability perspective, maximizing local energy utilization contributes to improving energy efficiency, reducing reliance on external energy sources, and enhancing the capacity of decentralized systems to absorb market shocks. For this reason, economic indicators such as Net Present Value (NPV) or payback period are not explicitly included in the optimization objective. This is justified by the focus of the analysis on short-term operational performance and exposure to electricity price volatility, rather than long-term investment evaluation. Moreover, given that the economic value of the REC is largely determined by shared energy volumes under the current Italian incentive scheme, maximizing local energy utilization provides a consistent proxy for economic performance. Nevertheless, the integration of financial metrics such as NPV or payback period represents a relevant extension for future research, particularly in the context of investment decision-making. Through panel econometric analysis, we estimate the sensitivity of economic value to electricity price fluctuations. Results show that RECs reduce price sensitivity by approximately 8–15% compared to individual users, as estimated by panel regression coefficients. Furthermore, the volatility of economic value decreases by around 1.95% under the community configuration, particularly during the 2022 price shock demonstrating that RECs exhibit significantly lower price dependence than standalone consumers. To assess the robustness of these findings, a machine learning framework is employed to relax linearity assumptions and capture potential non-linear effects. Results consistently show that while market prices remain an important determinant, RECs substantially attenuate their impact, particularly during periods of extreme price stress. A policy counterfactual comparison between pre- and post-reform incentive structures further indicates that the coefficient of variation decreases by approximately 4.4% under the post-reform incentive scheme, highlighting the role of policy design in supporting economically and operationally sustainable energy communities. Overall, this study develops a data-driven analysis based on a high-frequency synthetic dataset designed to reproduce realistic consumption and generation dynamics, providing robust evidence that RECs contribute not only to renewable energy deployment but also to the economic and systemic sustainability of electricity markets under conditions of high volatility. Full article

This study presents a technical assessment of solar energy systems for integrated agricultural use and rural electrification. A model village comprising 30 households was considered, and high-resolution hourly load profiles were developed to characterize consumption dynamics, including peak demand and sectoral distribution across residential, agricultural, public, healthcare, and commercial users. A 60 kW photovoltaic (PV) system was designed in conjunction with an independent solar thermal installation for hot water supply. The system configuration was established through component sizing and numerical modeling, incorporating heat transfer mechanisms and operational constraints. Time-dependent simulations performed in MATLAB (R2022b) evaluated PV power output, battery storage cycling, and thermal system performance over a 24-h horizon. A comparative analysis of standalone PV, hybrid PV/T, and decoupled PV–thermal configurations was conducted based on performance and operational criteria. The results indicate that separated electrical and thermal subsystems achieve improved cost-effectiveness, enhanced reliability, and reduced maintenance requirements. The proposed approach demonstrates the technical viability of solar-based energy systems for rural applications, supporting energy autonomy, reduced fossil fuel dependence, and sustainable agricultural development. Full article

This paper presents the modelling and dynamic analysis of a Virtual Synchronous Generator (VSG) operating under three representative load models: constant impedance (Z), constant power load (CPL), and composite ZIP (constant impedance, constant current, and constant power) loads. The VSG control strategy enables voltage-source converters to emulate the inertial behavior of synchronous machines. However, load characteristics strongly affect the stability of such systems, and CPLs can be particularly destabilizing because of their negative incremental impedance. This study provides a theoretical and simulation-based analysis of VSG performance under Z-, CPL, and ZIP load conditions. A swing-equation-based control model is linearized to obtain a reduced-order small-signal stability model. The incremental impedance properties of the load types are evaluated analytically, showing that CPL behavior reduces effective damping and can destabilize the system. The resulting analytical stability condition provides a practical basis for selecting virtual inertia and damping parameters. Practical DC-side energy storage and current-limiting constraints associated with inertia emulation are also discussed. The analysis is supported by simulation studies that quantify the influence of load dynamics on frequency stability and transient response. In contrast to current research, this paper offers a single comparative framework in which all load types are analyzed under the same operating conditions and derives analytical stability conditions that inform the selection of virtual inertia and damping parameters. Full article

Standalone photovoltaic DC energy systems must maintain bus voltage stability without grid support; however, abrupt load variations can cause a DC-bus voltage drop, reducing system reliability and disturbing connected equipment. Although battery-based energy storage is effective for long-duration power balancing, its response to instantaneous disturbances can be limited. This study proposes an energy stability strategy using supercapacitor-based ride-through control and required capacity sizing for fast DC-bus voltage support. The proposed controller continuously monitors the DC-bus voltage and, when a voltage drop is detected, immediately triggers supercapacitor discharge to compensate for the power deficit until the bus recovers. In addition, a design formulation is derived to estimate the required compensation energy, ride-through time, and minimum capacitance based on the expected power deficit, allowable DC-bus voltage drop, and initial supercapacitor voltage. Simulation results under step changes in load resistance show that the supercapacitor sized by the proposed method maintains the DC-bus voltage close to its reference value within the specified limit. Hardware experiments further validate the ride-through operation and show good agreement between the predicted and measured compensation times. Full article

Renewable energy sources (RESs) in microgrids are vital for sustainable and resilient power networks, especially in rural South Africa with diverse climatic conditions. Photovoltaic (PV) energy generation is intermittent, making it difficult to offer reliable electricity in varying conditions. The Proton Exchange Membrane Fuel Cell (PEMFC) and solar system are integrated in this study to provide a sustainable energy source that can address these issues. Under varying temperature and irradiance conditions, the PV system was evaluated with and without an LCL filter and PEMFC unit using PVGIS Northern Cape daily solar irradiation data. Results show that solar input variability causes large voltage fluctuations in the standalone PV system. This study adds to the expanding knowledge on RES resilience by utilising real-world climatic data and shows that PV-FC systems can be a sustainable and reliable option for microgrid and standalone applications in rural locations with ample resources or without electrical infrastructure. Full article

Decarbonizing industrial energy consumption is critical for global sustainability. This study evaluates renewable energy alternatives to replace fossil-fuel power generation at an oil and gas facility in Khurais, KSA. A comparative thermodynamic and economic assessment was performed between a photovoltaic (PV) array and a parabolic trough collector (PTC) integrated with a Brayton cycle (BC) and a bottoming organic Rankine cycle (RC). The PTC-BC-RC model includes multi-generation capabilities for electricity, process hot water, and hydrogen via a PEM electrolyzer. The baseline PTC-BC-RC system generates up to 118.1 MW with a maximum thermal efficiency of 36.57%. The PEM electrolyzer utilizes 2% of the generated power to produce hydrogen at 0.0152 kg/s. Economically, the recuperated CSP system offsets its higher initial capital costs through diverse revenue streams (power, heat, and hydrogen), achieving a payback period of 5.13 years, significantly outperforming the PV system’s 6.80 years. Both configurations mitigate annual emissions by 747,000 tons of CO₂, 103.4 tons of NO_x, and 3.72 tons of SO₂. Despite regional limitations such as dust and water scarcity, the multi-generation PTC-BC-RC system proves economically and thermodynamically superior to the standalone PV system, offering a highly effective decarbonization strategy for industrial facilities in arid, high-irradiance zones. Full article

This study presents a comprehensive techno-economic and environmental evaluation of ten standalone solar-powered mobile charging station configurations for mini electric vehicles (MEVs) in Kuwait, simulated using HOMER Pro (v3.18.4). The configurations span DC–AC and pure DC-bus architectures, fixed and tracking photovoltaic (PV) systems, hybrid designs incorporating diesel generator backup, and fully renewable zero-emission systems. All configurations were evaluated under identical load demand (6460 kWh/year), solar resource, and economic assumptions derived from Kuwait’s desert climate at Al-Wafra farms (28°33′52.7″ N, 48°03′45.8″ E, annual average GHI = 5.49 kWh·m⁻²·day⁻¹). Performance was assessed using Net Present Cost (NPC), Levelised Cost of Energy (LCOE), annual PV energy production, CO₂ emissions, Energy Production Density (EPD), Renewable Fraction (RF), and the PV Energy Production-to-Load Ratio (PV-EPTLR). The results demonstrate that two-axis tracking on a DC-bank architecture without a generator (System 8) achieves the highest annual PV output of 13,635 kWh/year, representing a 36% increase over a fixed-tilt DC-bank system while eliminating 100% of operational CO₂ emissions. Among the hybrid configurations, vertical single-axis tracking on a DC-bank architecture with generator backup (System 6) yields the lowest lifecycle cost (NPC = USD 6271.8; LCOE = 0.0751 USD/kWh), representing a 57% reduction relative to the fixed-tilt DC–AC baseline. EPD analysis confirms that tracking-based systems improve structural energy efficiency by up to 36%, making them particularly suitable for mobile and weight-constrained deployments. The findings provide actionable guidance for deploying sustainable off-grid MEV charging infrastructure in regions with limited grid access, offering a scalable pathway toward zero-emission rural transportation in solar-rich arid environments. The study further provides a systematic comparison between DC–AC and pure DC-bank charging architectures under identical operating conditions. Full article

With the increasing integration of photovoltaic (PV) generation, short-term scheduling of hydro–PV–battery energy storage systems (HPBS) faces growing challenges due to the stochastic variability of PV output, the temporal coupling of hydropower operation, and the accumulation of deviations during the real-time execution of day-ahead schedules. This paper proposes a bi-level coordinated scheduling framework that integrates day-ahead mixed-integer quadratic programming (MIQP) with intraday Soft Actor–Critic (SAC)-based correction. In the upper layer, MIQP generates a 24 h baseline schedule subject to unit output limits, mutually exclusive charging/discharging logic, and operational constraints. In the lower layer, SAC performs bounded real-time residual correction for hydropower and battery storage around the MIQP baseline, while a deviation-triggered replanning mechanism forms a closed-loop process of planning, execution, correction, and replanning. Comparative experiments under the tested setting show that SAC achieves better overall performance than Deep Deterministic Policy Gradient (DDPG), Twin Delayed Deep Deterministic Policy Gradient (TD3), and Proximal Policy Optimization (PPO). Typical-day evaluations under dry-, normal-, and wet-season conditions show that, in the selected case studies, the proposed MIQP + SAC framework achieves better performance than standalone MIQP and MIQP-Replan, which refers to a deviation-triggered MIQP re-optimization strategy, in load tracking, PV curtailment reduction, and hydro-storage coordination. These results indicate the effectiveness of the proposed framework for short-term HPBS scheduling under representative operating conditions. Full article

Decarbonizing the building sector requires integrating on-site renewable generation with systematic energy management. Among the most widely adopted alternatives are photovoltaic (PV) systems in buildings; however, they are often implemented as a standalone technological intervention (size–install–estimate savings), without being formally incorporated into an Energy Management System (EnMS) aimed at continuous improvement. In this context, this research addresses this gap through an integrated methodological framework aligned with ISO 50001, in which PV is explicitly included in energy performance management through energy review, the definition of an Energy Baseline (EnB), and the monitoring of Energy Performance Indicators (EnPIs) within the PDCA cycle. The approach articulates the analytical sizing of the PV system based on electricity demand and solar resources; its validation through simulation to ensure operational consistency and a technical, economic, and environmental assessment that translates PV generation into a verifiable reduction in energy imported from the grid and, consequently, into traceable improvements in EnPI under an audit-compatible scheme. The methodology is demonstrated in a multi-family building in Chorrillos, Lima (Peru), where a 14.5 kWp rooftop PV system (25 modules of 580 Wp) is designed to maximize self-consumption during daylight hours. The results show technical performance consistent with the demand profile, economic viability under the conditions of the case, and environmental benefits from replacing grid electricity, along with offsets associated mainly with the manufacture of PV components. The residual gap between the Post-PV EnPIs and the ISO 50001 target confirms that PV integration is a necessary but not sufficient first-cycle action within a comprehensive building decarbonization strategy, with demand-side management and envelope improvements identified as subsequent PDCA cycle priorities. In summary, the central contribution is not the PV sizing itself, but its operational and traceable integration within ISO 50001, making PV a quantifiable, verifiable, and scalable energy improvement action for residential buildings in emerging economies. Full article

This paper presents an adaptive nonlinear control and state observation framework for energy management in standalone photovoltaic (PV) systems integrated with battery energy storage. A unified nonlinear dynamic model is developed to describe the interactions between the PV generator, the DC/DC buck converter, and the lithium-ion battery. Based on this model, a multi-mode control strategy is designed to ensure efficient and safe operation under varying environmental and loading conditions. The proposed scheme incorporates maximum power point tracking (MPPT) to maximize photovoltaic energy extraction, along with constant current (CC) and constant voltage (CV) charging modes to guarantee battery safety and longevity. To address uncertainties and unmeasured states, an adaptive nonlinear observer is developed for real-time estimation of the battery open-circuit voltage and state of charge. The observer design is supported by Lyapunov-based stability analysis, ensuring boundedness and convergence of the estimation error in the presence of modeling uncertainties and external disturbances. An energy management algorithm is further introduced to coordinate the transition between operating modes according to the estimated system states and battery constraints. The effectiveness and robustness of the proposed control and observation strategy are validated through detailed simulations in MATLAB/Simulink under varying solar irradiance conditions. The results demonstrate accurate maximum power tracking, reliable state estimation, and safe battery charging performance, highlighting the potential of the proposed approach for advanced autonomous PV–battery systems. Full article

Street lighting systems are essential for ensuring nighttime road safety and visibility. The integration of solar photovoltaic (PV) systems into street lighting infrastructure improves energy efficiency and sustainability; however, the mismatch between daytime energy generation and nighttime lighting demand requires effective energy management solutions. In addition, long-distance electrical connections introduce voltage drop constraints, which are often overlooked in conventional design approaches. This study addresses the integration of lighting design, electrical constraints, and techno-economic performance in nanogrid-based LED street lighting systems for secondary roads. A unified framework is developed to evaluate lighting performance, PV–battery sizing, voltage drop behavior, and lifecycle cost under different system architectures. Optimal pole spacing and luminaire ratings are determined using DIALux, while PV–battery configurations are optimized using HOMER Pro based on site-specific solar irradiance. The analysis focuses on voltage drop as the key electrical constraint and examines its impact under decentralized and centralized nanogrid configurations (25%, 50%, and 100%) in both stand-alone and grid-connected modes. The results show that increasing centralization reduces component redundancy but significantly increases cable length, conductor sizing, and infrastructure cost. A techno-economic assessment with lifecycle cost and sensitivity analysis indicates that a 25% centralized configuration reduces total system cost by approximately 23% compared to fully decentralized systems while avoiding excessive cabling costs. These findings demonstrate that voltage drop and electrical infrastructure constraints play a decisive role in determining optimal system design, highlighting the importance of system-level integration rather than isolated optimization of lighting or energy components. Full article

This study evaluates the techno-economic performance of solar photovoltaic (PV) systems for powering a 7 t/day shea butter processing plant to address electricity constraints limiting rural processing and local value capture. Annual electricity demand is modeled under three operational scenarios: (i) a typical processing season from November to February; (ii) an extended season until mid-May; and (iii) near year-round operation with eleven months of processing. Using detailed load modeling and techno-economic simulations in HOMER Pro, off-grid PV/battery systems and grid-connected PV hybrids are compared using the levelized cost of electricity (LCOE). In scenario 1, the national grid remains the most cost-effective solution. Scenario 2 reveals that integrating 35% solar PV into the grid becomes economically attractive, offering a recoverable value of 263.33 thousand USD within 7.73 years. In scenario 3, the grid/PV/battery configuration emerges as the optimal solution, providing the lowest cost of electricity at 0.246 USD/kWh compared to 0.319 USD/kWh for a grid-only supply and delivering an internal rate of return (IRR) of 20.7%. Under the same scenario, the standalone PV/battery system also demonstrates strong economic viability, with a cost of 0.292 USD/kWh and an IRR of 9.2%, lower than average tariffs from PV mini-grid developers in sub-Saharan Africa. These results demonstrate the profitability and viability of PV-based systems in powering food processing facilities in off-grid regions. Full article

The accelerating adoption of electric vehicles (EVs) alongside renewable distributed generators (RE-DGs), particularly solar photovoltaic (PV) and wind-based systems, is reshaping the operational and planning paradigms of modern power distribution networks. In this study, an optimal allocation framework is developed for the simultaneous integration of EV charging stations (EVCSs) and RE-DGs within a looped configuration of the IEEE 33-bus distribution system. Two advanced metaheuristic techniques—Improved Grey Wolf Optimizer (IGWO) and Metaheuristic COOT-Based Optimization (MCBO)—are employed to determine the optimal siting and sizing of these resources. The optimization objectives focus on minimizing active power losses while enhancing voltage stability and reducing overall voltage deviation across the network. Simulation results reveal that the MCBO algorithm demonstrates superior performance, yielding a maximum reduction of 82.49% in active power losses with the integration of standalone PV, and 78.14% when PV is deployed in conjunction with EVCSs. Similarly, wind turbine generator (WTG) integration resulted in a loss reduction of 85.74% without EVCSs and 81.57% with EVCS integration using the same approach. The findings further indicate that looped network configurations consistently outperform traditional radial systems in both loss reduction and voltage profile enhancement, underscoring their suitability for accommodating future EV and renewable energy penetrations in smart distribution grids. Full article