Journal Description
Solar
Solar
is an international, peer-reviewed, open access journal on all aspects of solar energy and photovoltaic systems published quarterly online by MDPI.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within ESCI (Web of Science), Scopus and other databases.
- Journal Rank: CiteScore - Q2 (Environmental Science (miscellaneous))
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 21.3 days after submission; acceptance to publication is undertaken in 4.2 days (median values for papers published in this journal in the first half of 2025).
- Recognition of Reviewers: APC discount vouchers, optional signed peer review and reviewer names are published annually in the journal.
- Journal Cluster of Energy and Fuels: Energies, Batteries, Hydrogen, Biomass, Electricity, Wind, Fuels, Gases, Solar, ESA and Methane.
Latest Articles
Comparing Outdoor to Indoor Performance for Bifacial Modules Affected by Polarization-Type Potential-Induced Degradation
Solar 2025, 5(3), 43; https://doi.org/10.3390/solar5030043 - 4 Sep 2025
Abstract
►
Show Figures
Bifacial photovoltaic (PV) modules have the advantage of using light reflected off of the ground to contribute to power production. Predicting the energy gain is challenging and requires complex models to do so accurately. Often, module degradation over time is neglected in models
[...] Read more.
Bifacial photovoltaic (PV) modules have the advantage of using light reflected off of the ground to contribute to power production. Predicting the energy gain is challenging and requires complex models to do so accurately. Often, module degradation over time is neglected in models for the sake of simplicity or is underestimated. Comparing outdoor and indoor current–voltage (I–V) performance for bifacial modules is more challenging than for monofacial modules, as there are additional variables to consider such as rear albedo non-uniformity, cell mismatch, and their effects on temperature. This challenge is compounded when heterogeneous degradation modes occur, such as polarization-type potential-induced degradation (PID-p). To examine the effects of PID-p on I–V predictions using an empirical data-driven approach, 16 bifacial PERC modules are installed outdoors on racks with different albedo conditions. A subset is exposed to high-voltage biases of −1500 V or +1500 V. Outdoor data are traced at irradiance ranges of 150–250 W/m2, 500–600 W/m2, and 900–1000 W/m2. These curves are corrected using control module temperature, wire resistivity, and module resistance measured indoors. We examine several methods to transform indoor I–V curves to accurately, and more simply than existing methods, approximate outdoor performance for bifacial modules without and with varying levels of PID-p degradation. This way, bifacial performance modeling can be more accessible and informed by fielded, degraded modules. Distributions of percent errors between indoor and outdoor performance parameters and Mean Absolute Percent Errors (MAPEs) are used to assess method quality. Results including low-irradiance data (150–250 W/m2) are discussed but are filtered for quantifying method quality as these data introduce substantial errors. The method with the most optimal tradeoff between low MAPE and analysis simplicity involves measuring the front side of a module indoors at an irradiance equal to plane-of-array irradiance plus the product of module bifaciality and albedo irradiance. This method gives MAPE values of 1–6.5% for non-degraded and 1.6–5.9% for PID-p degraded module performance.
Full article
Open AccessArticle
Operating a Positive Temperature Coefficient Water Heater Powered by Photovoltaic Panels
by
Cameron Dolan, Ryan M. Smith, Henry Toal and Michelle Wilber
Solar 2025, 5(3), 42; https://doi.org/10.3390/solar5030042 - 3 Sep 2025
Abstract
Domestic water heaters traditionally use natural gas or electric resistance to heat stored water. A gas water heater relies on a non-renewable resource, while an electric water heater might rely on electricity generated by a non-renewable resource. This study analyzes the performance of
[...] Read more.
Domestic water heaters traditionally use natural gas or electric resistance to heat stored water. A gas water heater relies on a non-renewable resource, while an electric water heater might rely on electricity generated by a non-renewable resource. This study analyzes the performance of an electric water heater featuring a novel heating element design based on a positive temperature coefficient (PTC) material powered directly by solar photovoltaic (PV) modules in a northern latitude installation. The project analyzes the operation of two different design temperatures of the PTC heating elements (50 °C, and 70 °C) when fed by three solar PV panels during the spring in the high-latitude location of Anchorage, Alaska (61.2° N). Our results show that both design temperatures of the PTC heating elements are able to achieve self-regulation at a sufficient and safe operating temperature for a domestic use case. Analysis of water heater performance directly connected to PV power showed that the PTC-equipped water heater had a limited period of heating when sufficient solar irradiance is available. Because of this, restrictive use of the water heater might be necessary during periods of non-daylight hours to preserve hot water in an insulated tank. However, this PV-to-PTC setup could be effectively used in industrial, commercial, and research settings.
Full article
(This article belongs to the Topic Advances in Solar Heating and Cooling)
►▼
Show Figures

Figure 1
Open AccessArticle
Evaluation of a Hybrid Solar–Combined Heat and Power System for Off-Grid Winter Energy Supply
by
Eduard Enasel and Gheorghe Dumitrascu
Solar 2025, 5(3), 41; https://doi.org/10.3390/solar5030041 - 1 Sep 2025
Abstract
►▼
Show Figures
The study investigates a hybrid energy system integrating photovoltaic (PV) panels, micro-CHP units, battery storage, and thermal storage to meet the winter energy demands of a residential building in Bacău, Romania. Using real-world experimental data from amorphous, polycrystalline, and monocrystalline PV panels, C++
[...] Read more.
The study investigates a hybrid energy system integrating photovoltaic (PV) panels, micro-CHP units, battery storage, and thermal storage to meet the winter energy demands of a residential building in Bacău, Romania. Using real-world experimental data from amorphous, polycrystalline, and monocrystalline PV panels, C++ Model 1 simulates building energy needs and PV system performance under varying irradiance levels. The results show that PV systems alone cannot meet the total winter demand, with polycrystalline slightly outperforming monocrystalline, yet still falling short. A second computational model (C++ Model 2) simulates hybrid energy flow, demonstrating how the CHP unit and storage systems can ensure off-grid autonomy. The model dynamically manages energy between components based on daily irradiance scenarios. The findings reveal critical thresholds for PV surplus, optimal CHP sizing, and realistic battery and thermal storage needs. This paper provides a practical framework for designing efficient, data-driven hybrid solar–CHP systems for cold climates. The novelty lies in the integration of real-world PV efficiency data with a dynamic irradiance-driven simulation framework, enabling precise hybrid system sizing for winter-dominant regions.
Full article

Figure 1
Open AccessArticle
Where Can Solar Go? Assessing Land Availability for PV in Italy Under Regulatory Constraints
by
Babak Ranjgar, Alessandro Niccolai and Sonia Leva
Solar 2025, 5(3), 40; https://doi.org/10.3390/solar5030040 - 1 Sep 2025
Abstract
►▼
Show Figures
The expansion of solar photovoltaic (PV) energy is a central pillar of Italy’s climate and energy transition strategy. However, the actual availability of land for PV deployment is heavily influenced by a complex regulatory framework that imposes numerous spatial exclusions. This study presents
[...] Read more.
The expansion of solar photovoltaic (PV) energy is a central pillar of Italy’s climate and energy transition strategy. However, the actual availability of land for PV deployment is heavily influenced by a complex regulatory framework that imposes numerous spatial exclusions. This study presents a comprehensive geospatial analysis of exclusion zones for ground-mounted PV installations across Italy, integrating data from national regulations, environmental protection laws, and cultural heritage inventories. Using a vector-based overlay approach, we categorized constraints into six groups: natural assets, landscape protection, cultural heritage, natural hazards, environmental buffers, and infrastructural safety zones. The analysis shows that only approximately 26% of Italy’s land area remains available for PV development. Regional disparities are pronounced, with southern regions such as Sicilia and Puglia offering the highest availability, while northern and central regions face severe limitations due to dense overlays of protected landscapes and heritage sites. These findings offer quantitative support to the often-cited claim that Italy’s strict land-use regulations are a significant barrier to renewable energy development. The study highlights the need for more flexible, spatially informed regulatory frameworks to reconcile conservation priorities with the urgency of decarbonization.
Full article

Figure 1
Open AccessArticle
Optimization Study of the Electrical Microgrid for a Hybrid PV–Wind–Diesel–Storage System in an Island Environment
by
Fahad Maoulida, Kassim Mohamed Aboudou, Rabah Djedjig and Mohammed El Ganaoui
Solar 2025, 5(3), 39; https://doi.org/10.3390/solar5030039 - 4 Aug 2025
Abstract
►▼
Show Figures
The Union of the Comoros, located in the Indian Ocean, faces persistent energy challenges due to its geographic isolation, heavy dependence on imported fossil fuels, and underdeveloped electricity infrastructure. This study investigates the techno-economic optimization of a hybrid microgrid designed to supply electricity
[...] Read more.
The Union of the Comoros, located in the Indian Ocean, faces persistent energy challenges due to its geographic isolation, heavy dependence on imported fossil fuels, and underdeveloped electricity infrastructure. This study investigates the techno-economic optimization of a hybrid microgrid designed to supply electricity to a rural village in Grande Comore. The proposed system integrates photovoltaic (PV) panels, wind turbines, a diesel generator, and battery storage. Detailed modeling and simulation were conducted using HOMER Energy, accompanied by a sensitivity analysis on solar irradiance, wind speed, and diesel price. The results indicate that the optimal configuration consists solely of PV and battery storage, meeting 100% of the annual electricity demand with a competitive levelized cost of energy (LCOE) of 0.563 USD/kWh and zero greenhouse gas emissions. Solar PV contributes over 99% of the total energy production, while wind and diesel components remain unused under optimal conditions. Furthermore, the system generates a substantial energy surplus of 63.7%, which could be leveraged for community applications such as water pumping, public lighting, or future system expansion. This study highlights the technical viability, economic competitiveness, and environmental sustainability of 100% solar microgrids for non-interconnected island territories. The approach provides a practical and replicable decision-support framework for decentralized energy planning in remote and vulnerable regions.
Full article

Figure 1
Open AccessArticle
Development and Evaluation of a Solar Milk Pasteurizer for the Savanna Ecological Zones of West Africa
by
Iddrisu Ibrahim, Paul Tengey, Kelci Mikayla Lawrence, Joseph Atia Ayariga, Fortune Akabanda, Grace Yawa Aduve, Junhuan Xu, Robertson K. Boakai, Olufemi S. Ajayi and James Owusu-Kwarteng
Solar 2025, 5(3), 38; https://doi.org/10.3390/solar5030038 - 4 Aug 2025
Abstract
►▼
Show Figures
In many developing African countries, milk safety is often managed through traditional methods such as fermentation or boiling over firewood. While these approaches reduce some microbial risks, they present critical limitations. Firewood dependency contributes to deforestation, depletion of agricultural residues, and loss of
[...] Read more.
In many developing African countries, milk safety is often managed through traditional methods such as fermentation or boiling over firewood. While these approaches reduce some microbial risks, they present critical limitations. Firewood dependency contributes to deforestation, depletion of agricultural residues, and loss of soil fertility, which, in turn, compromise environmental health and food security. Solar pasteurization provides a reliable and sustainable method for thermally inactivating pathogenic microorganisms in milk and other perishable foods at sub-boiling temperatures, preserving its nutritional quality. This study aimed to evaluate the thermal and microbial performance of a low-cost solar milk pasteurization system, hypothesized to effectively reduce microbial contaminants and retain milk quality under natural sunlight. The system was constructed using locally available materials and tailored to the climatic conditions of the Savanna ecological zone in West Africa. A flat-plate glass solar collector was integrated with a 0.15 cm thick stainless steel cylindrical milk vat, featuring a 2.2 cm hot water jacket and 0.5 cm thick aluminum foil insulation. The system was tested in Navrongo, Ghana, under ambient temperatures ranging from 30 °C to 43 °C. The pasteurizer successfully processed up to 8 L of milk per batch, achieving a maximum milk temperature of 74 °C by 14:00 GMT. Microbial analysis revealed a significant reduction in bacterial load, from 6.6 × 106 CFU/mL to 1.0 × 102 CFU/mL, with complete elimination of coliforms. These results confirmed the device’s effectiveness in achieving safe pasteurization levels. The findings demonstrate that this locally built solar pasteurization system is a viable and cost-effective solution for improving milk safety in arid, electricity-limited regions. Its potential scalability also opens avenues for rural entrepreneurship in solar-powered food and water treatment technologies.
Full article

Figure 1
Open AccessReview
Assessing the Possibility to Enhance the Stability of Hybrid Perovskite Solar Cells: A Brief Review
by
Alexander Axelevitch and David Lugassy
Solar 2025, 5(3), 37; https://doi.org/10.3390/solar5030037 - 4 Aug 2025
Abstract
Solar cells based on the hybrid perovskite absorbers had shown very high growth of their conversion efficiency almost reaching to the Shockley–Queisser limit during last decade. However, low stability prevents to widely use them in industry and in everyday life. Possible reasons and
[...] Read more.
Solar cells based on the hybrid perovskite absorbers had shown very high growth of their conversion efficiency almost reaching to the Shockley–Queisser limit during last decade. However, low stability prevents to widely use them in industry and in everyday life. Possible reasons and pathways to remedy of instability and degradation of the perovskite solar cells are considered in this review. Specific attention was paid to the thermodynamical analysis of the hybrid perovskite absorber.
Full article
(This article belongs to the Special Issue Developments in Perovskite Solar Cells)
►▼
Show Figures

Figure 1
Open AccessArticle
Experimental Studies on Partial Energy Harvesting by Novel Solar Cages, Microworlds, to Explore Sustainability
by
Mohammad A. Khan, Brian Maricle, Zachary D. Franzel, Gabe Gransden and Matthew Vannette
Solar 2025, 5(3), 36; https://doi.org/10.3390/solar5030036 - 1 Aug 2025
Abstract
►▼
Show Figures
Sources of renewable energy have attracted considerable attention. Their expanded use will have a substantial impact on both the cost of energy production and climate change. Solar energy is one efficient and safe option; however, solar energy harvesting sites, irrespective of the location,
[...] Read more.
Sources of renewable energy have attracted considerable attention. Their expanded use will have a substantial impact on both the cost of energy production and climate change. Solar energy is one efficient and safe option; however, solar energy harvesting sites, irrespective of the location, can impact the ecosystem. This experimental study explores the energy available inside and outside of novel miniature energy harvesting cages by measuring light intensity and power generated. Varying light intensity outside the cage has been utilized to study the remaining energy inside the cage of a flexible design, where the heights of the harvesting panels are parameters. Cages are built from custom photovoltaic panels arranged in a staircase manner to provide access to growing plants. The balance between power generation and biological development is investigated. Two different structures are presented to explore the variation of illumination intensity inside the cages. The experimental results show a substantial reduction in energy inside the cages. The experimental results showed up to 24% reduction in illumination inside the cages in winter. The reduction is even larger in summer, up to 57%. The results from the models provide a framework to study the possible impact on a biological system residing inside the cages, paving the way for practical farming with sustainable energy harvesting.
Full article

Figure 1
Open AccessArticle
Techno-Economic Assessment of Electrification and Hydrogen Pathways for Optimal Solar Integration in the Glass Industry
by
Lorenzo Miserocchi and Alessandro Franco
Solar 2025, 5(3), 35; https://doi.org/10.3390/solar5030035 - 1 Aug 2025
Abstract
►▼
Show Figures
Direct electrification and hydrogen utilization represent two key pathways for decarbonizing the glass industry, with their effectiveness subject to adequate furnace design and renewable energy availability. This study presents a techno-economic assessment for optimal solar energy integration in a representative 300 t/d oxyfuel
[...] Read more.
Direct electrification and hydrogen utilization represent two key pathways for decarbonizing the glass industry, with their effectiveness subject to adequate furnace design and renewable energy availability. This study presents a techno-economic assessment for optimal solar energy integration in a representative 300 t/d oxyfuel container glass furnace with a specific energy consumption of 4.35 GJ/t. A mixed-integer linear programming formulation is developed to evaluate specific melting costs, carbon emissions, and renewable energy self-consumption and self-production rates across three scenarios: direct solar coupling, battery storage, and a hydrogen-based infrastructure. Battery storage achieves the greatest reductions in specific melting costs and emissions, whereas hydrogen integration minimizes electricity export to the grid. By incorporating capital investment considerations, the study quantifies the cost premiums and capacity requirements under varying decarbonization targets. A combination of 30 MW of solar plant and 9 MW of electric boosting enables the realization of around 30% carbon reduction while increasing total costs by 25%. Deeper decarbonization targets require more advanced systems, with batteries emerging as a cost-effective solution. These findings offer critical insights into the economic and environmental trade-offs, as well as the technical constraints associated with renewable energy adoption in the glass industry, providing a foundation for strategic energy and decarbonization planning.
Full article

Figure 1
Open AccessArticle
Spatial Strategies for the Renewable Energy Transition: Integrating Solar Photovoltaics into Barcelona’s Urban Morphology
by
Maryam Roodneshin, Adrian Muros Alcojor and Torsten Masseck
Solar 2025, 5(3), 34; https://doi.org/10.3390/solar5030034 - 23 Jul 2025
Abstract
►▼
Show Figures
This study investigates strategies for urban-scale renewable energy integration through a photovoltaic-centric approach, with a case study of a district in Barcelona. The methodology integrates spatial and morphological data using a geographic information system (GIS)-based and clustering framework to address challenges of CO
[...] Read more.
This study investigates strategies for urban-scale renewable energy integration through a photovoltaic-centric approach, with a case study of a district in Barcelona. The methodology integrates spatial and morphological data using a geographic information system (GIS)-based and clustering framework to address challenges of CO2 emissions, air pollution, and energy inefficiency. Rooftop availability and photovoltaic (PV) design constraints are analysed under current urban regulations. The spatial analysis incorporates building geometry and solar exposure, while an evolutionary optimisation algorithm in Grasshopper refines shading analysis, energy yield, and financial performance. Clustering methods (K-means and 3D proximity) group PV panels by solar irradiance uniformity and spatial coherence to enhance system efficiency. Eight PV deployment scenarios are evaluated, incorporating submodule integrated converter technology under a solar power purchase agreement model. Results show distinct trade-offs among PV scenarios. The standard fixed tilted (31.5° tilt, south-facing) scenario offers a top environmental and performance ratio (PR) = 66.81% but limited financial returns. In contrast, large- and huge-sized modules offer peak financial returns, aligning with private-sector priorities but with moderate energy efficiency. Medium- and large-size scenarios provide balanced outcomes, while a small module and its optimised rotated version scenarios maximise energy output yet suffer from high capital costs. A hybrid strategy combining standard fixed tilted with medium and large modules balances environmental and economic goals. The district’s morphology supports “solar neighbourhoods” and demonstrates how multi-scenario evaluation can guide resilient PV planning in Mediterranean cities.
Full article

Figure 1
Open AccessArticle
Failure Behavior of Aluminum Solar Panel Mounting Structures Subjected to Uplift Pressure: Effects of Foundation Defects
by
Sachi Furukawa, Hiroki Mikami, Takehiro Okuji and Koji Takamori
Solar 2025, 5(3), 33; https://doi.org/10.3390/solar5030033 - 15 Jul 2025
Abstract
►▼
Show Figures
This study investigates the failure behavior of aluminum solar panel mounting structures subjected to uplift pressure, with particular focus on conditions not typically considered in conventional design, specifically, foundation defects. To clarify critical failure modes and evaluate potential countermeasures, full-scale pressure loading tests
[...] Read more.
This study investigates the failure behavior of aluminum solar panel mounting structures subjected to uplift pressure, with particular focus on conditions not typically considered in conventional design, specifically, foundation defects. To clarify critical failure modes and evaluate potential countermeasures, full-scale pressure loading tests were conducted. The results showed that when even a single column base was unanchored, structural failure occurred at approximately half the design wind pressure. Although reinforcement measures—such as the installation of uplift-resistant braces—increased the failure pressure to 1.5 times the design value, they also introduced the risk of undesirable failure modes, including panel detachment. Additionally, four-point bending tests of failed members and joints, combined with structural analysis of the frame, demonstrated that once the ultimate strength of each component is known, the likely failure location within the structure can be reasonably predicted. To prevent panel blow-off and progressive failure of column bases and piles, specific design considerations are proposed based on both experimental observations and numerical simulations. In particular, avoiding local buckling in members parallel to the short side of the panels is critical. Furthermore, a safety factor of approximately two should be applied to column bases and pile foundations to ensure structural integrity under unforeseen foundation conditions.
Full article

Figure 1
Open AccessArticle
A Multi-Scale Approach to Photovoltaic Waste Prediction: Insights from Italy’s Current and Future Installations
by
Andrea Franzoni, Chiara Leggerini, Mariasole Bannò, Mattia Avanzini and Edoardo Vitto
Solar 2025, 5(3), 32; https://doi.org/10.3390/solar5030032 - 15 Jul 2025
Abstract
►▼
Show Figures
Italy strives to meet its renewable energy targets for 2030 and 2050, with photovoltaic (PV) technology playing a central role. However, the push for increased solar adoption, spurred by past incentive schemes such as “Conto Energia” and “Superbonus 110%”,
[...] Read more.
Italy strives to meet its renewable energy targets for 2030 and 2050, with photovoltaic (PV) technology playing a central role. However, the push for increased solar adoption, spurred by past incentive schemes such as “Conto Energia” and “Superbonus 110%”, raises long-term challenges related to PV waste management. In this study, we present a multi-scale approach to forecast End-of-Life (EoL) PV waste across Italy’s 20 regions, aiming to support national circular economy strategies. Historical installation data (2008–2024) were collected and combined with socio-economic and energy-related indicators to train a Backpropagation Neural Network (BPNN) for regional PV capacity forecasting up to 2050. Each model was optimised and validated using R2 and RMSE metrics. The projections indicate that current trends fall short of meeting Italy’s decarbonisation targets. Subsequently, by applying a Weibull reliability function under two distinct scenarios (Early-loss and Regular-loss), we estimated the annual and regional distribution of PV panels reaching their EoL. This analysis provides spatially explicit insights into future PV waste flows, essential for planning regional recycling infrastructures and ensuring sustainable energy transitions.
Full article

Figure 1
Open AccessArticle
Zero Emissions Analysis for a Hybrid System with Photovoltaic and Thermal Energy in the Balearic Islands University
by
Pere Antoni Bibiloni-Mulet, Andreu Moià-Pol, Jacinto Vidal-Noguera, Iván Alonso, Víctor Martínez-Moll, Yamile Díaz Torres, Vicent Canals, Benito Mas and Carles Mulet-Forteza
Solar 2025, 5(3), 31; https://doi.org/10.3390/solar5030031 - 4 Jul 2025
Abstract
The University of the Balearic Islands is undertaking a significant energy transition toward a zero-emissions model, motivated by escalating energy costs and strong institutional commitments to climate neutrality. This study investigates the technical and operational feasibility of deploying 7.1 MWp of photovoltaic capacity
[...] Read more.
The University of the Balearic Islands is undertaking a significant energy transition toward a zero-emissions model, motivated by escalating energy costs and strong institutional commitments to climate neutrality. This study investigates the technical and operational feasibility of deploying 7.1 MWp of photovoltaic capacity across the campus, integrated with Li-FePO4 battery systems and thermal energy storage. Through a detailed analysis of hourly energy demand, PV generation profiles, and storage constraints, the research evaluates how these technologies can be optimized to meet campus needs. A linear optimization model is applied to assess system performance under the constraint of a 3 MW grid export limit. Furthermore, the potential of demand-side electrification, implemented via a centralized HVAC plant and a 4th–5th generation district heating and cooling network, is analyzed in terms of its ability to maximize on-site PV self-consumption and reduce reliance on grid electricity during non-generation periods.
Full article
(This article belongs to the Special Issue XIX Iberian Congress and XV Ibero-American Congress on Solar Energy (CIES 2024))
►▼
Show Figures

Figure 1
Open AccessArticle
Evaluating Solar Energy Potential Through Clear Sky Index Characterization Across Elevation Profiles in Mozambique
by
Fernando Venâncio Mucomole, Carlos Augusto Santos Silva and Lourenço Lázaro Magaia
Solar 2025, 5(3), 30; https://doi.org/10.3390/solar5030030 - 1 Jul 2025
Abstract
The characteristics and types of the sky can greatly influence photovoltaic (PV) power generation, potentially leading to a reduction in both the lifespan and efficiency of the entire system. Driven by the challenge of addressing fluctuations in solar PV energy utilization, the aim
[...] Read more.
The characteristics and types of the sky can greatly influence photovoltaic (PV) power generation, potentially leading to a reduction in both the lifespan and efficiency of the entire system. Driven by the challenge of addressing fluctuations in solar PV energy utilization, the aim was to assess the solar energy potential by analyzing the clear sky index across elevation profiles. To achieve this, a theoretical model for determining was employed, which encapsulated the solar energy analysis. Initially, solar energy data collected from approximately 16 stations in various provinces of Mozambique, as part of the solar energy measurement initiatives by INAM, FUNAE, AERONET, and Meteonorm, was processed. Subsequently, the clear sky radiation was calculated, and was established. The statistical findings indicate a reduction in energy contribution from the predictors, accounting for 28% of the total incident energy; however, there are progressive increases averaging around ~0.02, with values ranging from 0.4 to 0.9, demonstrating a strong correlation between 0.7 and 0.9 across several stations and predictor parameters. No significant climate change effects were noted. The radiation flux is directed from areas with higher to those with lower values, as illustrated in the heat map. The region experiences an increase in atmospheric parameter deposition, with concentrations around ~0.20, yet there remains a substantial energy flow potential of 92% for PV applications. This interaction can also be applied in other locations to assess the potential for available solar energy, as the analyzed solar energy spectrum aligns closely with the theoretical statistical calibration of energy distribution relevant to the global solar energy population process.
Full article
(This article belongs to the Topic Solar Forecasting and Smart Photovoltaic Systems)
►▼
Show Figures

Figure 1
Open AccessArticle
Optimizing Zinc Selenide and Silicon-Based Heterojunction Solar Cells for Enhanced Photovoltaic Performance
by
Amina Laouid, Amine Alaoui Belghiti, Ali Abouais, Krzysztof Wisniewski, Mouhaydine Tlemçani, Przemysław Płóciennik, Abdelowahed Hajjaji and Anna Zawadzka
Solar 2025, 5(3), 29; https://doi.org/10.3390/solar5030029 - 25 Jun 2025
Abstract
►▼
Show Figures
In the purpose of enhancing solar cell efficiency and sustainability, zinc selenide (ZnSe) and silicon (Si) play indispensable roles, offering a compelling combination of stability and transparency while also highlighting their abundant availability. This study utilizes the SCAPS_1D tool to explore diverse heterojunction
[...] Read more.
In the purpose of enhancing solar cell efficiency and sustainability, zinc selenide (ZnSe) and silicon (Si) play indispensable roles, offering a compelling combination of stability and transparency while also highlighting their abundant availability. This study utilizes the SCAPS_1D tool to explore diverse heterojunction setups, aiming to solve the nuanced correlation between key parameters and photovoltaic performance, therefore contributing significantly to the advancement of sustainable energy solutions. Exploring the performance analysis of heterojunction solar cell configurations employing ZnSe and Si elements, various configurations including SnO2/ZnSe/p_Si/p+_Si, SnO2/CdS/p_Si/p+_Si, TiO2/ZnSe/p_Si/p+_Si, and TiO2/CdS/p_Si/p+_Si are investigated, delving into parameters such as back surface field thickness (BSF), doping concentration, operating temperature, absorber layer properties, electron transport layer properties, interface defects, series and shunt resistance. Among these configurations, the SnO2/ZnSe/p_Si/p+_Si configuration with a doping concentration of 1019 cm−3 and a BSF thickness of 2 μm, illustrates a remarkable conversion efficiency of 22.82%, a short circuit current density (Jsc) of 40.33 mA/cm2, an open circuit voltage (Voc) of 0.73 V, and a fill factor (FF) of 77.05%. Its environmentally friendly attributes position it as a promising contender for advanced photovoltaic applications. This work emphasizes the critical role of parameter optimization in propelling solar cell technologies toward heightened efficiency and sustainability.
Full article

Figure 1
Open AccessArticle
Barrio-Level Assessment of Solar Rooftop Energy and Initial Insights into Energy Inequalities in Puerto Rico
by
Carlos A. Peña-Becerra, Willian A. Pacheco-Cano, Daniel F. Aragones-Vargas, Agustín Irizarry-Rivera and Marcel Castro-Sitiriche
Solar 2025, 5(2), 28; https://doi.org/10.3390/solar5020028 - 19 Jun 2025
Abstract
►▼
Show Figures
The transition to renewable energy is critical to enhance Puerto Rico’s energy resilience and reduce dependence on imported fossil fuels. Rooftop photovoltaic (PV) systems provide a scalable opportunity to meet these objectives. This study evaluates the potential of rooftop PV systems across Puerto
[...] Read more.
The transition to renewable energy is critical to enhance Puerto Rico’s energy resilience and reduce dependence on imported fossil fuels. Rooftop photovoltaic (PV) systems provide a scalable opportunity to meet these objectives. This study evaluates the potential of rooftop PV systems across Puerto Rico using the National Renewable Energy Laboratory’s (NREL) PV Rooftop Database, processing detailed roof surface data to estimate installed capacity, energy generation, Levelized Cost of Electricity (LCOE), and solar resource potential at municipal and barrio levels. Findings reveal high solar rooftop capacity in urban neighborhoods, with areas like Sabana Abajo and Hato Tejas each exceeding 450 GWh/year in potential generation. Solar rooftop resource values peak at 3.67 kWh/kW in coastal areas, with LCOE values (0.071–0.215 USD/kWh) below current electricity rates. All municipalities demonstrate technical potential to meet their electricity demand with rooftop PV system alone. This research contributes through (1) developing Puerto Rico’s first comprehensive solar rooftop potential map; (2) providing unprecedented barrio-level analysis; (3) introducing a methodology for estimating missing post-disaster consumption data; and (4) integrating technical, economic, and equity indicators to inform energy policy. These findings demonstrate the importance of rooftop solar in achieving renewable energy goals and provide an understanding of spatial energy inequalities.
Full article

Figure 1
Open AccessArticle
Steam Generation for Industry Using Linear Fresnel Solar Collectors and PV-Driven High-Temperature Heat Pumps: Techno-Economic Analysis
by
Antonio Famiglietti and Ruben Abbas
Solar 2025, 5(2), 27; https://doi.org/10.3390/solar5020027 - 17 Jun 2025
Abstract
Steam is widely used in industry as a heat carrier for thermal processes and is primarily generated by gas-fired steam boilers. The decarbonization of industrial thermal demand relies on the capability of clean and renewable technologies to provide steam through reliable and cost-effective
[...] Read more.
Steam is widely used in industry as a heat carrier for thermal processes and is primarily generated by gas-fired steam boilers. The decarbonization of industrial thermal demand relies on the capability of clean and renewable technologies to provide steam through reliable and cost-effective systems. Concentrating solar thermal technologies are attracting attention as a heat source for industrial steam generation. In addition, electricity-driven high-temperature heat pumps can provide heat using either renewable or grid electricity by upgrading ambient or waste heat to the required temperature level. In this study, linear Fresnel solar collectors and high-temperature heat pumps driven by photovoltaics are considered heat sources for steam generation in industrial processes. Energetic and economic analyses are performed across the European countries to assess and compare their performances. The results demonstrate that for a given available area for the solar field, solar thermal systems provide a higher annual energy yield in southern countries and at lower costs than heat pumps. On the other hand, heat pumps driven by photovoltaics provide higher annual energy for decreasing solar radiation conditions (central and northern Europe), although it leads to higher costs than solar thermal systems. A hybrid scheme combining the two technologies is the favorable option in central Europe, allowing a trade-off between the costs and the energy yield per unit area.
Full article
(This article belongs to the Special Issue XIX Iberian Congress and XV Ibero-American Congress on Solar Energy (CIES 2024))
►▼
Show Figures

Figure 1
Open AccessArticle
Photovoltaic Farm Power Generation Forecast Using Photovoltaic Battery Model with Machine Learning Capabilities
by
Agboola Benjamin Alao, Olatunji Matthew Adeyanju, Manohar Chamana, Stephen Bayne and Argenis Bilbao
Solar 2025, 5(2), 26; https://doi.org/10.3390/solar5020026 - 6 Jun 2025
Abstract
►▼
Show Figures
This study presents a machine learning-based photovoltaic (PV) model for energy management and planning in a microgrid with a battery system. Microgrids integrating PV face challenges such as solar irradiance variability, temperature fluctuations, and intermittent generation, which impact grid stability and battery storage
[...] Read more.
This study presents a machine learning-based photovoltaic (PV) model for energy management and planning in a microgrid with a battery system. Microgrids integrating PV face challenges such as solar irradiance variability, temperature fluctuations, and intermittent generation, which impact grid stability and battery storage efficiency. Existing models often lack predictive accuracy, computational efficiency, and adaptability to changing environmental conditions. To address these limitations, the proposed model integrates an Adaptive Neuro-Fuzzy Inference System (ANFIS) with a multi-input multi-output (MIMO) prediction algorithm, utilizing historical temperature and irradiance data for accurate and efficient forecasting. Simulation results demonstrate high prediction accuracies of 95.10% for temperature and 98.06% for irradiance on dataset-1, significantly reducing computational demands and outperforming conventional prediction techniques. The model further uses ANFIS outputs to estimate PV generation and optimize battery state of charge (SoC), achieving a consistent minimal SoC reduction of about 0.88% (from 80% to 79.12%) over four different battery types over a seven-day charge–discharge cycle, providing up to 11 h of battery autonomy under specified load conditions. Further validation with four other distinct datasets confirms the ANFIS network’s robustness and superior ability to handle complex data variations with consistent accuracy, making it a valuable tool for improving microgrid stability, energy storage utilization, and overall system reliability. Overall, ANFIS outperforms other models (like curve fittings, ANN, Stacked-LSTM, RF, XGBoost, GBoostM, Ensemble, LGBoost, CatBoost, CNN-LSTM, and MOSMA-SVM) with an average accuracy of 98.65%, and a 0.45 RMSE value on temperature predictions, while maintaining 98.18% accuracy, and a 31.98 RMSE value on irradiance predictions across all five datasets. The lowest average computational time of 17.99s was achieved with the ANFIS model across all the datasets compared to other models.
Full article

Figure 1
Open AccessArticle
Barriers and Challenges in the Implementation of Decentralized Solar Water Disinfection Treatment Systems—A Case of Ghana
by
Abdul-Rahaman Afitiri and Ernest Kofi Amankwa Afrifa
Solar 2025, 5(2), 25; https://doi.org/10.3390/solar5020025 - 31 May 2025
Abstract
►▼
Show Figures
Decentralized solar water disinfection systems (DSODIS) in continuous flow systems are alternatives for large-scale improved water access in rural contexts. However, DSODIS in rural Ghana are limited. An exploratory sequential mixed-methods design was used to explore the enablers of and barriers to, as
[...] Read more.
Decentralized solar water disinfection systems (DSODIS) in continuous flow systems are alternatives for large-scale improved water access in rural contexts. However, DSODIS in rural Ghana are limited. An exploratory sequential mixed-methods design was used to explore the enablers of and barriers to, as well as reported barrier perceptions to, the effective implementation of DSODIS in the Sawla-Tuna-Kalba (STK) District of Ghana. The qualitative data (26 respondents) were analyzed thematically, and the quantitative data (1155 household heads) were subjected to Poisson regression analyses. Enablers were categorized into themes such as willingness to pay for DSODIS, household and community participation, and willingness to use water from DSODIS. Similarly, the barriers include environmental barriers, technological barriers, economic barriers, and political and legal barriers. Household characteristics such as main water source and income, age group, education, marital status, household size, being born in the community, and years living in the community are statistically associated with reported barrier perceptions. Households with unimproved water sources and high income (IRR = 1.432, p = 0.000) and improved water sources and high income (IRR = 1.295, p = 0.000) are 43% and 30% more likely, respectively, to report more barrier perceptions compared with households with unimproved water sources and low income. Females (IRR = 1.070, p = 0.032) are marginally more likely to report more barrier perceptions compared with males. The model output also indicates that household heads with higher educational attainment (IRR = 1.152, p = 0.001) are 15% more likely to report more barrier perceptions compared with those with no formal education. These findings provide valuable information for policymakers and stakeholders aiming to provide quality water in rural Ghana where centralized systems cannot be installed.
Full article

Figure 1
Open AccessArticle
Solar Photovoltaic Diagnostic System with Logic Verification and Integrated Circuit Design for Fabrication
by
Abhitej Divi and Shuza Binzaid
Solar 2025, 5(2), 24; https://doi.org/10.3390/solar5020024 - 30 May 2025
Cited by 1
Abstract
►▼
Show Figures
Solar photovoltaic (PV) panels are the best solution to reduce greenhouse gas emissions by fossil fuel combustion, with global capability now exceeding 714 GW due to rapid technological advances in solar panels (SPs). However, SPs’ efficiency and lifespan remain limited due to the
[...] Read more.
Solar photovoltaic (PV) panels are the best solution to reduce greenhouse gas emissions by fossil fuel combustion, with global capability now exceeding 714 GW due to rapid technological advances in solar panels (SPs). However, SPs’ efficiency and lifespan remain limited due to the absence of advanced fault-detection systems, and they are prone to short circuits (SC), open circuits (OC), and power degradation. Therefore, this large-scale production requires reliable, real-time fault diagnosis to maintain panel performance. However, traditional diagnostic methods implemented using MPPT, neural networks, or microcontroller-based systems often rely on complex computational algorithms and are not cost-effective. So, this paper proposes a diagnostic system composed of six functional blocks to address this issue. The proposed system was initially verified using an Intel DE-10 Lite FPGA board. Once its functionality was confirmed, an ASIC design was proposed for mass production, offering a significantly lower implementation cost and reduced hardware complexity than prior methods. Different circuit designs were developed for each of the six blocks. All designs were created using Cadence software and TSMC 180 nm technology files. The basic components used in these designs include PMOS transistors with 300 nm channel length and 2 µm width, NMOS transistors with 350 nm channel length and 2 µm width, as well as resistors and capacitors. Differential amplifiers with a gain of 40 dB were used for voltage and current sensing from the SP. The chip activation signal generator circuit was designed with an adjustable frequency and generated 120 MHz and 100 MHz signals in this work. The decision-making block, Logic Driver Circuit, was innovatively implemented using a reduced number of transistors. A custom memory block with a reset switch was also implemented to store the fault value detected at the SP. Finally, the proposed ASIC was implemented for fabrication, which is highly cost-effective in mass production and does not require complex computational stages.
Full article

Figure 1
Highly Accessed Articles
Latest Books
E-Mail Alert
News
Topics
Topic in
Clean Technol., Energies, Materials, Solar, Sustainability
Smart Solar Energy Systems
Topic Editors: Venizelos Efthymiou, Minas PatsalidesDeadline: 30 September 2025
Topic in
Energies, Photonics, Sustainability, Solar, Nanomaterials
Photovoltaic Materials and Devices—2nd Edition
Topic Editors: Bin Yang, Yongbo YuanDeadline: 31 December 2025
Topic in
Energies, Entropy, Photonics, Technologies, Optics, Solar
Advances in Solar Technologies, Second Edition
Topic Editors: Jayanta Deb Mondol, Annamaria Buonomano, Biplab DasDeadline: 31 March 2026
Topic in
Buildings, Energies, Environments, Sustainability, Urban Science, Solar
Sustainable Built Environment, 2nd Volume
Topic Editors: Siu-Kit Lau, Vesna Kosorić, Abel Tablada, Miljana Horvat, Milena Vukmirović, Silvia Domingo-Irigoyen, Marija Todorović, Jérôme H. Kaempf, Kosa Golić, Ana Peric, Tatjana KosićDeadline: 30 April 2026

Conferences
Special Issues
Special Issue in
Solar
Developments in Perovskite Solar Cells
Guest Editor: Terry Chien-Jen YangDeadline: 31 December 2025
Special Issue in
Solar
Solar Energy for Cooling and Heating: Theory, Methods and Applications
Guest Editors: Andreu Moià-Pol, Iván Alonso de MiguelDeadline: 30 January 2026
Special Issue in
Solar
Efficient and Reliable Solar Photovoltaic Systems: 2nd Edition
Guest Editors: Philippe Poure, Shamsodin TaheriDeadline: 20 July 2026