Solar-Powered Electric Vehicles: Comprehensive Review of Technology Advancements, Challenges, and Future Prospects

Abstract

This comprehensive review examines the evolution, current state, and future potential of solar-powered electric vehicles (SEVs) and vehicle-integrated photovoltaics (VIPV). This study analyzed 77 relevant scientific papers published up to March 2025, identifying significant advancements in photovoltaic efficiency, lightweight materials, and integration techniques. Although SEVs and VIPV show promising potential for sustainable mobility, challenges remain in areas such as energy yield optimization, climate adaptability, and economic viability. This review highlights research gaps and proposes future directions, emphasizing the need for standardized testing protocols, improved energy management systems, and innovative material solutions to address these challenges. Key findings include the development of SEVs from early prototypes to limited commercial applications, the importance of the design and integration of solar photovoltaic systems, advancements in energy management and optimization, the use of lightweight materials, and the impact of climate and shading factors on performance. The review concludes by outlining directions for future research on the advancement of energy management systems, with particular emphasis on optimizing solar energy input, battery efficiency, and economic viability. Furthermore, it is recommended to investigate materials that achieve an optimal balance between durability, cost-effectiveness, and photovoltaic performance, as well as to develop adaptive solar capture designs tailored to diverse vehicle platforms.

1. Introduction

The transportation sector is a major contributor to global carbon emissions, driving the urgent need for sustainable alternatives to mitigate climate change and environmental degradation [1,2]. According to Statista [3], in recent decades, the European Union (EU) has made significant progress in reducing emissions across various sectors of the economy, with the notable exception of the transportation sector. In 2022, road vehicles were responsible for approximately 755 MtCO₂ emissions across the EU [3,4,5,6]. This figure represents 75% of the transportation sector’s total emissions and positions road vehicles as the leading source of carbon pollution in the EU, with passenger cars accounting for approximately 24.1% of all greenhouse gas emissions within this sector [7,8]. To address this issue, the EU has outlined objectives for its member countries in a document titled Sustainable and Smart Mobility Strategy, aiming to reduce carbon emissions in the transport sector by 90% by 2050 [9,10]. Among these alternatives, electric vehicles (EVs) have emerged as a promising solution, offering significant potential to reduce greenhouse gas emissions and dependence on fossil fuels [2,11,12]. The market for EVs is growing, and different renewable alternatives for vehicular technologies have been introduced. The transition from internal combustion engine vehicles (ICEVs) to EVs represents a paradigm shift in personal and commercial transportation, underscoring the importance of evaluating the environmental performance of EVs across their entire lifecycle.

The EV market is experiencing significant growth, characterized by a continuous influx of new entrants in the automotive sector and a notable shift from traditional propulsion systems to vehicles powered by alternative fuels and renewable hybrid systems [13]. This trend highlights the transformative potential of EVs in both the transportation and energy industries. Advances in the energy efficiency and design of photovoltaic (PV) solar cells [14,15], alongside the manufacturing and application of lightweight materials in automobiles [16,17], have facilitated the emergence of EVs equipped with vehicle-integrated photovoltaics (VIPV). These vehicles are now entering the market, offering an extended electric range and greater integration of renewable energy in transportation.

Numerous scientific articles have been published on various aspects of solar-powered electric vehicles. A general search for articles on solar-powered vehicles in Scopus (see Figure 1) indicates a recent surge in interest in solar-powered vehicles since their initial introduction in the early 1990s. Additionally, some authors have reviewed the scientific literature on solar-powered electric vehicles, focusing on different aspects of the topic.

Commault et al. [18] offered a comprehensive overview of PV technologies used in the context of VIPV, with particular emphasis on flexible and lightweight PV technologies and their potential for integration into electric vehicles. Pochont et al. [19] conducted another review that examined the energy generation capabilities of VIPV and presented a case study conducted in India to assess the potential solar energy yield across various driving routes in a tropical climate region. Additionally, another study by Fragassa et al. [20] focused on enhancing the overall vehicle performance by optimizing the materials, lay-up, and sandwich structures to achieve weight reduction and improved safety.

Table 1. Summary of current review papers and their area of focus.

Study Reference No.	Title	Type of Vehicles Reviewed	Focus Area of the Review
[18]	Overview and perspectives for vehicle-integrated photovoltaics	Various vehicles, primarily EVs	Vehicle integrated PV product technologies; PV cell/module integration
[19]	Recent trends in photovoltaic technologies for sustainable transportation in passenger vehicles—A review	Four-wheeled passenger vehicles	Vehicle integrated photovoltaics (VIPV) technologies, module integration, trends, tropical case study
[20]	On the structural behavior of a CFRP safety cage in a solar powered electric vehicle	Solar race vehicles	CFRP safety cage structural behavior, weight reduction, safety optimization
[21]	Investigation of Effective Factors on Vehicles Integrated Photovoltaic (VIPV) Performance: A Review	VIPV-equipped vehicles (e.g., vans)	Factors affecting VIPV performance: installation, solar cell characteristics, environmental constraint
[22]	Integration of solar energy in electrical, hybrid, autonomous vehicles: a technological review	Electric, hybrid, and autonomous vehicles (including 3- and 4-wheeled and robots)	Solar PV integration in EVs, hybrids, autonomous vehicles; barriers and challenges

provides a summary of the current review studies and their area of focus.

While existing studies provide detailed reviews on specific aspects of solar electric vehicle (SEV) technology, there is a clear absence of a current and comprehensive synthesis that systematically links recent advancements in the SEV field with ongoing challenges, new applications, and clearly defined future research paths. This review seeks to address this gap by offering an up-to-date and holistic analysis of the current SEV landscape. Specifically, it critically examines the evolutionary development of SEVs, tracing their journey from foundational concepts to modern prototypes and initial commercial models. It also explores the current technological frontiers and specific breakthroughs in crucial enabling areas, such as photovoltaic cell efficiency, lightweight material science and integration, and advanced energy management systems, which are relevant to vehicular applications. The diverse obstacles and significant challenges—ranging from technical limitations (e.g., optimizing energy output under varying conditions), economic feasibility (e.g., cost-effectiveness of integrated PV), and operational resilience (e.g., adaptability to climate and durability)—that currently impede widespread SEV adoption are examined in this study. This review also covers the range of existing and emerging use cases for SEVs as documented in recent scientific literature, moving beyond theoretical potential to practical applications. Building on this, the study outlines precise and actionable future research directions designed to strategically address these gaps, thereby promoting targeted innovation to accelerate the overall development and practical deployment of SEV technologies in the future.

2. Materials and Methods

The initial phase of the methodology involved developing a database comprising data from the literature pertinent to solar electric vehicles. To achieve this, sources were selected from various scientific data repositories.

A comprehensive literature review was conducted using the Web of Science and Scopus databases to identify relevant articles published until 12 March 2025. Scopus yielded a much greater number of publications using the same keywords, and the studies identified in the Web of Science were also included in Scopus. Therefore, the latter was selected as the primary source of eligible publications for this review.

The primary search terms included broad descriptors such as “Photovoltaic-powered vehicles”, “solar-powered electric vehicles”, “Vehicles Integrated Photovoltaic” (VIPV), “PV-Powered Electric Vehicles”, and “solar electric vehicles”.

The initial search produced a substantial collection of 469 papers, encompassing diverse scientific outputs to provide a comprehensive perspective on the scope and historical development of the literature in this specific field. The second phase of the methodology involved data filtering, and duplicate entries were eliminated. The selection of the relevant literature was guided by specific criteria, such as the inclusion of at least one keyword and publication in a scientific journal, while exclusion criteria encompassed conference papers (203), book chapters (19), reviews (13), conference reviews (12), and retracted papers (1), resulting in 221 articles. Notably, the language was restricted to English.

To enhance the quality of the data for analysis, the third phase involved identifying the primary scientific themes and subthemes addressed by the literature and excluding topics that appeared similar but had different applications. For example, some studies categorized Battery Electric Vehicles (BEVs) as solar electric vehicles when the charging infrastructure was powered by solar energy or a renewable energy grid mix. These articles were excluded from the analysis because this review focuses on vehicles with integrated solar panels rather than BEVs that are merely charged by solar energy. The final dataset was compiled by manually screening the abstracts of each article.

The final phase involved a detailed analysis of the identified subthemes. The literature within each sub-theme was analyzed as a cluster, ultimately leading to conclusions regarding the evolution of SEVs, energy optimization, solar technology and design trends, and future perspectives. In total, 77 papers were reviewed and discussed in the review articles. The flowchart of the selection process is shown in Figure 2.

As part of the research process, we wish to disclose that Perplexity AI (pro version) and Paperpal (pro version) were employed as assistive tools during the development of this manuscript. The AI was not used to generate original research content but rather to support the following activities:

• Literature Summarization: After downloading and reviewing over 70 scientific papers, the Perplexity AI (pro version) was used to help distill key findings, trends, and themes—particularly in organizing information related to SEV evolution, material design, and optimization strategies.
• Language and Clarity Enhancement: The Paperpal AI tool assisted in rewriting selected portions of the text to improve grammatical accuracy, technical clarity, and overall readability, especially in sections like the introduction and conclusion.
• Critical Structuring and Feedback: Both tools were used as a first-pass reviewer to critique the logical flow of arguments and provide feedback on redundancy or verbosity in the draft. All AI-generated feedback was manually reviewed and revised by the authors to ensure fidelity to the source materials and scientific accuracy.

3. Results and Discussion

Prior to exploring the subthemes presented in the literature, it is necessary to clarify some terms frequently encountered in academic discourse. Vehicles that depend on solar energy have been variously identified as solar-powered electric vehicles (SPEV), solar-powered vehicles (SPV), solar electric vehicles, all of which mean the same thing, and VIPV. In many publications, these terms have been used interchangeably.

Solar electric vehicles are defined as vehicles that primarily or entirely utilize solar energy as their power source for propulsion. These vehicles are equipped with extensive solar arrays that often cover a significant portion of their surfaces to capture sunlight. The captured sunlight is converted into electricity using PV panels, which are then used to power the vehicle, typically via an electric motor. SEVs prioritize solar energy as the principal or exclusive energy source and incorporate energy storage systems, such as batteries, to facilitate operation during periods of low sunlight [23,24,25]. In contrast, vehicle-integrated photovoltaics refer to the integration of photovoltaic cells into the structure of a vehicle (e.g., roof, hood, windows, or sides) to generate electricity as a supplementary power source. In contrast to retrofitted solar panels, VIPV systems are integrated into the vehicle structure during manufacturing. These modules can power auxiliary systems, recharge the main battery, or assist propulsion. VIPV is considered a step toward sustainable mobility by utilizing unused vehicle surfaces for energy generation [26,27,28].

Table 2. Differences between SPEV and VIPV.

Aspect	Solar-Powered Electric Vehicle (SPEV)	Vehicle-Integrated Photovoltaics (VIPV)
Definition	A vehicle equipped with solar panels to generate electricity for propulsion or battery storage [23,24].	Photovoltaic modules can be integrated directly into the vehicle structure during the design phase [26,27].
Implementation	Solar panels are typically mounted on exposed surfaces like roofs or hoods [23,24].	PV modules are seamlessly incorporated into the vehicle’s exterior for structural and functional optimization [26,27].
Purpose	To supplement or replace traditional charging methods with solar energy [23,25].	To maximize energy generation, the unused surface areas of the vehicle are utilized [26,28].
Design Integration	Panels may be added post-manufacture or as part of a specific model design [23,24].	It is fully integrated into the vehicle design, considering aesthetics and functionality [27,28].
Applications	It primarily extends the driving range and reduces the reliance on grid electricity. It is mostly used in solar race competitions [23,24].	Powers auxiliary systems, recharges batteries, and reduces CO2‚ emissions significantly [28].
Examples	Vehicles such as Lightyear One, Aptera, and Sono Motors Sion use solar panels to extend their range [28].	Demonstration vehicles such as the Toyota Prius Prime, Hyundai Ioniq 5, and Sono Sion are equipped with high-efficiency VIPV modules [28].

provides a summary of key differences between SPEV and VIPV.

Simply put, solar-powered electric vehicles (SPEV) and solar electric vehicles (SEV) refer to the same concept—vehicles designed to operate primarily or entirely on solar energy; solar-powered vehicles (SPV) is a broader term that can include both electric and hybrid vehicles utilizing solar power; and vehicle-integrated photovoltaics (VIPV) refers specifically to the integration method and technology, not the vehicle type itself. Although both SEVs and VIPV aim to harness solar energy for electric vehicles, they differ significantly in their approach, integration, and market readiness. VIPV offers a more immediate and adaptable solution for enhancing the sustainability of electric vehicles by providing supplementary energy to improve efficiency and reduce dependence on external charging.

In contrast, SEVs strive for energy independence by relying on solar power for propulsion, representing a specialized category that often focuses on demonstrating the potential of solar energy in transportation.

By applying first-principle thinking, the authors of this review observed that there appears to be no substantial or fundamental difference between SEV and VIPV beyond their design integration. Both technologies share the same application, require identical photovoltaic technology for electricity conversion, utilize batteries for energy storage, serve the same purpose, and most significantly, operate on the same fundamental principles. Therefore, SEV and VIPV denote the same concept in this review paper, and for the purpose of consistency, the term SEV will be utilized in this review paper encompassing all solar-powered electric vehicle concepts regardless of integration method.

Figure 3 illustrates a VIPV prototype from Lightyear One, and Figure 4 shows the synoptic diagram of a solar electric vehicle integrated into a photovoltaic system. The roofs or certain body parts of vehicles exposed to sunlight are replaced with photovoltaic solar cells, which are subsequently connected to batteries for energy storage. In both cases, the operational principle remains consistent with that of a Battery Electric Vehicle; however, in this case, the energy source is derived directly from sunlight rather than a charging infrastructure.

Further discussion of the results of the analysis will be reviewed under the following sub-topics:

• Historical evolution
• Vehicle Technology Development and Design

  ○

  Design and Integration

  ○

  Energy Management

  ○

  Lightweight Material

• Present Application
• Weather Conditions and Shading Effects
• Economic and Market Analysis
• Conclusions

3.1. Evolution of Solar Electric Vehicles (SEV)

3.1.1. Early Conceptions and Prototypes (1950s–1980s)

The origin of solar-powered vehicles can be traced back to mid-20th-century investigations into renewable energy applications. In 1955, William G. Cobb of General Motors introduced the Sunmobile, a 15-inch prototype powered by 12 selenium photovoltaic cells. Although rudimentary, it demonstrated the feasibility of solar propulsion at the 1955 GM Powerama Exhibition [31,32]. By the 1970s, practical experimentation in this field had increased significantly. British engineer Alan Freeman developed a three-wheeled solar-electric hybrid in 1976, combining pedal power with solar-charged batteries, which subsequently became the U.K.’s first road-legal solar vehicle following electric vehicle tax exemptions in 1981 [32].

A significant milestone occurred in 1982 with the Quiet Achiever, a solar-powered vehicle that traveled 4000 km across Australia in 20 days, maintaining an average speed of 14 mph. Constructed by Hans Tholstrup and engineers Larry and Garry Perkins, this accomplishment demonstrated the potential of solar mobility for long-distance travel [31]. Simultaneously, academic endeavors such as Tel Aviv University’s Ugly Duckling (1980) exemplified early attempts to balance power and practicality, utilizing 432 solar cells to generate 400 W despite limitations in solar cell efficiency (approximately 10%) and the presence of heavy batteries [31].

These initial attempts encountered technological challenges, such as insufficient energy density and infeasible designs for large-scale manufacturing. Nonetheless, they established a basis for incorporating photovoltaic technology into vehicular systems and highlighted the use of lightweight materials and aerodynamic efficiency [33,34].

3.1.2. Development of Solar Car Racing and Practical Prototypes (1980s–2000s)

The 1987 World Solar Challenge marked a pivotal moment in the evolution of solar vehicle technology, encouraging competitive innovation. General Motors’ Sunraycer, in collaboration with AeroVironment and Hughes Aircraft, achieved a dominant performance in the inaugural race, completing 3005 km at an average speed of 66.9 km/h. Equipped with 8800 solar cells and a motor with an efficiency of 92%, it established new standards, subsequently inspiring GM’s Impact prototype, the precursor to modern electric vehicles [31,34].

By the 2000s, solar vehicles had progressed to functional prototypes. Notably, Sunswift III in Australia traversed the continent in 5.5 days in 2007, and Brazil’s ecoTech Solar was recognized as an early commercial solar electric vehicle [33]. In 2007, Twente One from the Netherlands pioneered the use of pivoting solar panels and Fresnel lenses to enhance energy capture, while Japan’s Tokai Falcon focused on optimizing aerodynamics [31,33]. In 2008, the Sasol Solar Challenge in South Africa and Purdue University’s innovations in lightweight composites further promoted advancements in energy management of solar electric vehicles [33,34].

Despite these developments, challenges such as partial shading and reliance on hybrid systems, necessitating further innovations in power electronics and regenerative braking [33,35].

3.1.3. Modern Trends and Commercialization Efforts (2010s–Present)

The past decade has marked a significant transition in solar-powered electric vehicles (EVs) and vehicle-integrated photovoltaics (VIPV), which have evolved from experimental prototypes to limited commercial applications. In 2015, the “Stella Lux” by Solar Team Eindhoven showcased the practical potential of generating surplus energy from a solar-powered vehicle [36]. In 2016, Toyota’s Prius PHV became the first mass-produced automobile to incorporate rooftop solar panels, extending its electric range by 6.1 km/day [31,32]. Hyundai’s Sonata Hybrid in 2020 and Lightyear One in 2022 further advanced the technology, achieving 30–45 km/day ranges by utilizing 20–30% efficient cells [31,37]. Commercialization efforts intensified in 2019 with Sono Motors’ Sion, which featured 330 solar panels integrated across its body, and Lightyear’s development of curved solar roofs. The Solar World GT in 2021 demonstrated VIPV’s potential for autonomous operation by circumnavigating the globe solely on solar power [31,36]. Mainstream manufacturers have also advanced VIPV adoption. In 2023, Toyota signaled plans to integrate solar energy into future EVs, targeting a 10–15% range increase by 2030 [38]. Tesla has explored solar concepts, such as a Cybertruck solar back bed cover patent, but prioritized grid-charged EVs [38].

Current academic research focuses on high-efficiency solar cells (e.g., perovskite/silicon) and aesthetic integration, with projections indicating a 60% cost reduction by 2030 [33,34]. In April 2024, the International Electrotechnical Commission (IEC) developed industrial standards, designated IEC TC 82 PT 600, for vehicle-integrated photovoltaics. This document addresses the technical and environmental considerations pertaining to VIPV [39]. Advancements in solar-powered electric vehicles indicate progress in photovoltaic efficiency, lightweight materials, and aerodynamics. Nevertheless, the energy yield from vehicle-integrated photovoltaics (VIPV) remains limited; a peak power output of 700 W to 1 kW translates to a daily energy production of 2–3 kWh, which is insufficient for most electric vehicles that require 124–186 Wh per km. Consequently, solar energy continues to serve as a supplementary power source, with grid charging remaining the predominant source.

Although technical progress has been made, the economic viability and practical energy contribution of solar power remain elusive, positioning it as a niche enhancer rather than a stand-alone solution [40]. A development timeline of solar electric vehicles is shown in Figure 5.

3.2. Solar Vehicle Technology Development and Design

Solar vehicle technology has emerged as a promising solution for sustainable transportation, combining the benefits of renewable energy and electric mobility. The integration of photovoltaic (PV) systems into vehicles has seen significant advancements in recent years, driven by improvements in solar cell efficiency, design innovations, and the growing demand for clean energy. The development of solar vehicles involves a multidisciplinary approach encompassing various aspects such as PV technology, vehicle design, and energy management systems. This section will be discussed under the following themes:

3.2.1. Design and Integration of Solar Photovoltaic Systems in Electric Vehicles

The integration of photovoltaic (PV) technology into electric vehicles has advanced significantly, with various cell technologies showing promise for vehicular applications. The design of the vehicle involves three major considerations—size, shape, and materials used [41]. Only one study [42] examined two principal methodologies for integrating photovoltaic (PV) systems into vehicles: Vehicle-Added PV (VAPV) and Vehicle-Integrated PV (VIPV). The VAPV approach involves adding solar panels to existing vehicle designs, typically on the roof. In contrast, the VIPV approach entails the direct integration of solar cells into the vehicle body during manufacturing. Although the VAPV method is simpler, it may lead to increased additional weight. Conversely, the VIPV method offers superior weight optimization and aesthetics, but necessitates more complex design considerations. Figure 6 and Figure 7 below show different prototypes of VAPV and VIPV design, respectively.

Imdoukh et al. [43] designed a three-wheeled solar-powered electric vehicle in Kuwait. The vehicle was equipped with a monitoring system to check the voltage and current levels of PV modules. According to the author, the implemented vehicle could accommodate one passenger, handle up to 300 kg, and has a driving range of approximately 30 km or 1 h of battery life, assuming operation with a fully charged battery on a cloudy day. Khare et al. [44] conducted a design and assessment study in India, where the authors modeled a solar-powered electric vehicle system. A 0.75-KW motor was required to run the vehicle, which was powered by a 500 W solar panel, and energy was stored in a 23-Ah battery. The vehicle cost was minimized using three distinct optimization methods: grasshopper, krill herd, and cuckoo optimization techniques.

Another important part of the design is PV technologies. Yamaguchi et al. [15,45] and Jeddi et al. [46] conducted a comparative study of different PV arrays used in solar cars. They analyzed different cell technologies, finding that III-V compound triple-junction solar cells demonstrated superior performance with potential efficiencies of 37% and better temperature coefficients (−0.19% °C⁻¹) than silicon-based alternatives (−0.29% °C⁻¹ for Si back contact cells). This translates to greater potential driving ranges—up to 30 km/day on average and exceeding 50 km/day under optimal conditions. These thin crystalline silicon (c-Si) solar cells offer enhanced durability, adaptability, and portability, making them particularly suitable for automotive applications. Samadi et al. [47] investigated the integration of various types of solar cells into vehicle-integrated photovoltaic (VIPV) systems to enhance energy efficiency. The authors proposed several methodologies, including direct integration, utilization of concentrator surfaces, modification of module structures, use of alternative materials, miniaturization, and alterations in solar cell layout. They concluded that determining the most suitable type of solar cell for VIPV applications is challenging because of factors such as manufacturers’ preferences, cost, and geographical influences.

Su et al. [48] developed flexible CIGS (CuIn_1−xGa_xSe₂) thin-film solar cells with 17.2% efficiency, highlighting their advantages for vehicle integration owing to their lightweight properties and conformability to curved surfaces. Their implementation showed a 35% increase in full-charge endurance compared to vehicles without solar integration. A design study conducted at the University of Twente explored conceptual PV applications for various modes of transport, including public transportation, electric bicycles, and utility vehicles [49]. The authors’ broader approach to solar vehicle integration highlights the potential for diverse applications and the need for innovative design solutions to address challenges, such as limited space for PV cell integration and effective visual communication of the concept’s intended function.

Figure 6. Prototypes of VAPV Designs. (a) Alan Freeman’s 1979 Solar powered Car. Adopted from [50]. (b) The Quiet Achiever: Solar Trek. Adopted from [51]. (c) Solar-Powered tricycle. Adopted from [52]. (d) Sanyo Truck with Mounted PV. Adopted from [53].

Figure 6. Prototypes of VAPV Designs. (a) Alan Freeman’s 1979 Solar powered Car. Adopted from [50]. (b) The Quiet Achiever: Solar Trek. Adopted from [51]. (c) Solar-Powered tricycle. Adopted from [52]. (d) Sanyo Truck with Mounted PV. Adopted from [53].

Figure 7. Different VIPV Designs. (a) Lightyear One. Adopted from [54]. (b) Toyota Prius. Adopted from [55]. (c) Hyundai-Sonata. Adopted from [56]. (d) Bluekens-Delivery Van. Adopted from [57].

Figure 7. Different VIPV Designs. (a) Lightyear One. Adopted from [54]. (b) Toyota Prius. Adopted from [55]. (c) Hyundai-Sonata. Adopted from [56]. (d) Bluekens-Delivery Van. Adopted from [57].

In another design work, Kehinde et al. [58] focused on the design and fabrication of the static body of a solar-powered shuttle. A square-pipe frame was designed above the shuttle to balance the solar panels. Tahjib et al. [59] presented a simulation-based design of a solar-powered three-wheel tadpole vehicle. A data-logging system was developed to analyze the vehicle’s performance. The authors proposed that the design could allow forensic analysis of the possible causes of an accident by recording operational parameters under various road conditions.

Heeraman et al. [60] discussed the design and fabrication of solar-powered vehicles, focusing on the chassis, which is the foundation for any vehicle, the braking system, battery pack and charging system, and the motor system. The authors used a programming and numeric computing platform called MATLAB. The simulation focused on providing structural support and stability to the SEVs. The choice of chassis is determined by elements such as the vehicle weight, battery pack dimensions, and powertrain. The chassis material must be robust, lightweight, and durable to guarantee optimal performance and safety.

Kutler et al. [61] introduced innovative photovoltaic module technology and a production method for seamless integration into commercial truck box body roofs, potentially unlocking 90.2 GW of power in the EU. The researchers’ technique involved laminating c-Si photovoltaic cells with an Ethylene Tetrafluoroethylene (ETFE) top cover onto standard Glass Fiber Reinforced Polymer (GFRP) hard-foam sandwich elements, which can be directly fitted using conventional box body profiles. A mega Electronics e-Worker was outfitted with a photovoltaic-active box featuring the initial version of the proposed module technology. After 10 months of outdoor operation, preliminary monitoring results were reported, indicating the promising real-world weather resistance of the proposed module

The integration of PV panels on Light Electric Vehicles (LEVs) has been explored by Lee et al. [62]. By combining simulations based on meteorological data with real-world measurements from an electric scooter prototype, this study confirmed a strong correlation between simulated and actual PV power output. The results led to design suggestions for cost-effective and energy-efficient integrated PV panels on LEVs, indicating that under favorable conditions, the energy generated over a day could exceed the daily energy consumption of the vehicle.

Table 3. Comparison between different vehicle type design and integration method.

Vehicle	Number of Solar Cells	Integration Method	Solar Power Output	Motor Power	Daily Solar Range	Maximum Range
Lightyear 0/One	782 cells	Fully integrated (roof, hood, boot)	700 W–1 kW	4 in-wheel motors	30–70 km/day	625–725 km (WLTP)
Sono Motors Sion	330 cells	Fully integrated (entire body)	~500 W	120 kW (163 hp)	30–45 km/day	305 km (WLTP)
Toyota Prius PHV (Production)	Not specified	Roof-mounted	180 W	Hybrid system	6.1 km/day	Hybrid range
Toyota Prius PHV (Demo)	Not specified	Integrated (roof, hood, boot)	860 W	Hybrid system	44.5 km/day	Hybrid range
Hyundai Sonata Hybrid	Not specified	Roof-mounted	Not specified	Hybrid system	Variable	Hybrid range

shows comparison between existing VIPV technologies, their method of integration and solar output power.

From all the papers reviewed in this section, SEVs have witnessed remarkable advancements in recent years, particularly in the development of photovoltaic (PV) cell efficiencies and integration methods. These improvements have brought society closer to the vision of widespread solar-powered transportation systems. However, despite these significant strides, several challenges persist that require further research and development to fully realize the potential of solar-powered vehicles. The following areas have been identified for future research and development:

• Lack of standardization in VIPV designs: The goal is to develop industrial standards that allow for seamless integrating of solar panels into vehicle designs without compromising aesthetics or aerodynamics. This includes exploring flexible and curved solar panels that can conform to various vehicle surfaces and investigating transparent solar cells that could potentially be integrated into windows and windshields. Establishing industry-wide standards for design, installation, and performance metrics would facilitate easier integration across different vehicle models and manufacturers, potentially accelerating the adoption of solar electric vehicles.
• Trade-offs between aesthetics, weight, and energy efficiency: Current solutions present complex trade-offs between aesthetics, weight, and energy efficiency that must be carefully balanced by designers. Researchers should focus on multidisciplinary approaches to harmonize these competing demands. These solutions struggle to simultaneously optimize sleek styling, lightweight construction, and maximum solar energy generation without sacrificing their performance. Emerging innovations such as transparent solar windows, adaptive panel designs, and advanced composite materials offer promising pathways to reconcile these competing demands. Future research should focus on consumer acceptance studies, comprehensive life cycle analyses, and hybrid energy systems to further optimize solar EV performance.

3.2.2. Energy Management and Optimization

Apart from design and integration, another important topic is the energy efficiency of solar vehicles. Many parts of the motor and drive system, power electronics, and converters contribute to the energy efficiency of solar cars. Starting with the novel designs of brushless motors and controllers used early in the GM Sunrayce competition [63] and the design of an in-wheel electric motor used by Aurora in the World Solar Challenge [64], the objective of each new component design is to improve the energy efficiency of electric vehicles. In two separate studies, Nivas et al. [65] and Ramamoorthy et al. [66] modeled and analyzed the use of solar energy resources for powering electric vehicles using MATLAB—a mathematical modeling tool. Their model used a battery for energy storage, PV panels that absorb radiation from sunlight and generate electrical power, a maximum power point tracker (MPPT) to track the maximum power, and a buck boost converter to amplify the DC voltage procured from the photovoltaic module. The boosted output was then transmitted to a three-phase voltage-source inverter (VSI). Ramamoorthy et al., went further to propose the use of BLDC motors and PV panels to enhance the driving range of electric vehicles (EVs) and reduce system costs. Cesar et al. [67] used a sensorless brushless DC motor (BLDC) drive control to optimize the energy between solar PV and battery. When the system was coupled with a regenerative braking mechanism, the vehicle’s range was extended by efficiently recovering kinetic energy through the battery with 30.60% efficiency.

Ocran et al. [68] proposed an artificial neural network MPPT for solar electric vehicles. The MPPT is based on a highly efficient boost converter with an insulated gate bipolar transistor power switch. The obtained energy was used to charge the lithium-ion battery stack of the solar vehicle. Taleb et al. [69] focused on the use of an inverter for the control strategy in SEV. The inverter used in this study was a three-phase inverter of the IRAMY20UP60B type. The proposed control strategy was tested on a locally manufactured EV prototype. The results showed that the EV prototype can be propelled at a speed of up to 60 km/h under different road conditions.

Macias et al. [70] conducted research on the optimization of PV modules integrated into vehicles. This study introduced a modeling tool for VIPV, which calculates the effective irradiance on the VIPV surface using Light Detection and Ranging point clouds to assess the direct component and sky images for diffuse irradiance. Subsequently, the energy produced by the VIPV module was determined using circuit simulation software. The results indicate substantial daily energy production and variations under partial shading conditions for different configurations (up to 41%).

Oosthuizen et al. [71] combined a set of optimization algorithms with methods of finding and using the expected values of forecasted weather variables to create an optimal speed profile for a solar electric vehicle to minimize energy usage while traveling the furthest distance during the Sasol Solar Challenge in 2018. These algorithms and Probability Mass Functions were implemented and tested during a challenge on South African national roads, spanning a vast distance of 2396 km under varying weather conditions and challenging route topographies. The two algorithms in question are as follows: the first optimizes stored energy on a high-resolution, single-day basis by controlling the vehicle speed, and the second optimizes the distance over multiple days at a lower resolution by managing the additional road traveled each day. The results are significant in predicting the energy required by a solar electric vehicle traveling along a route in South Africa, highlighting the crucial role of optimal speed requirements in achieving the best outcomes. The authors of this paper assert that implementing this work on the Sun Chaser III solar car contributed to its first-place position among local teams and fourth place internationally because of the accuracy and robustness of the work.

Advancements in power management are critical for optimizing the performance of solar-powered vehicles. Zhu et al. [72] proposed a two-stage multiple-vector model predictive control system for vehicles equipped with six-phase electric-drive-reconstructed onboard chargers. This approach not only improved the power density and reduced costs, but also optimized energy utilization during both the charging and driving modes, thereby enhancing the overall system efficiency.

Saleh et al. [73] investigated the conversion of plug-in electric golf carts into solar-powered vehicles using fuzzy logic control to optimize system parameters such as solar panel dimensions, vehicle weight, and speed. Their findings highlighted substantial cost reductions from decreased battery replacement needs, environmental benefits from eliminating tailpipe emissions, and opportunities for incorporating supercapacitors to enhance energy efficiency. Table 4 provides a summary of the various energy management and optimization methods of the reviewed literature.

The development of advanced energy management systems is vital for optimizing solar energy utilization in vehicles. Energy management in solar electric vehicles (SEVs) plays a critical role in enabling efficient, reliable, and sustainable operation. The core objectives include extending vehicle range by reducing energy losses, preserving battery longevity through controlled charging/discharging cycles, and maximizing overall system efficiency by optimizing energy conversion across subsystems such as MPPT controllers, converters, and motor drives.

These objectives are supported by real-time optimization strategies that address the unique operational challenges of SEVs. Notably, solar input is inherently variable, influenced by time of day, weather conditions, and shading. In parallel, driving patterns and terrain introduce dynamic energy demands. One method of dealing with the problem of uneven light intensity distribution in different parts of the vehicle and further enhancing the efficiency of SEV energy management strategy would be the application of asynchronous distributed control methods [74]. While this method has been applied in buildings by Zhai et al. [74], optimization systems in vehicles must therefore balance energy generation, storage, and consumption under constantly shifting conditions. This includes forecasting solar availability, regulating charge flow to prevent battery stress, and adapting motor output for optimal performance. Together, these measures ensure that SEVs can function effectively with minimal reliance on external grid charging, reinforcing their viability as a future-forward solution for low-carbon transportation.

Table 4. Summary of energy management and optimization methods for SEVs.

Study Refs.	Method/Technology	Description	Outcome/Benefit
[65,66]	MATLAB-based energy modeling	Model incorporating PV panels, MPPT, buck-boost converter, inverter, and BLDC motor	Improved energy flow, system efficiency, and EV range
[67]	Sensorless BLDC motor + regenerative braking	Control method optimizing energy flow between PV and battery using BLDC + braking energy recovery	30.6% improved energy recovery, extended vehicle range
[68,75]	AI-based MPPT (Artificial Neural Network)	Neural-network-driven MPPT integrated with a boost converter and lithium-ion battery charging system	High efficiency in energy tracking and storage
[69]	Three-phase inverter control	Use of IRAMY20UP60B inverter for propulsion control under varied road conditions	Achieved stable propulsion up to 60 km/h
[70,76]	PV module optimization using 3D LiDAR + simulation	Energy modeling tool using LiDAR point clouds and circuit simulation to predict shading and yield	Quantified shading effects; improved module positioning
[71]	Route-based energy optimization using weather forecasts	Optimal speed profiling and distance planning using PMF and algorithms for the Sasol Solar Challenge	Improved efficiency and ranked 1st nationally in competition
[72]	Predictive control system (multi-vector MPC)	A two-stage model predictive controller for energy use in driving and charging	Increased power density, lower costs, and optimized energy use
[73]	Fuzzy logic control in converted golf carts	Optimization of solar panel dimensions, speed, and weight for energy-efficient operation	Lower battery wear, emission-free transport, and energy savings

Table 4. Summary of energy management and optimization methods for SEVs.

Study Refs.	Method/Technology	Description	Outcome/Benefit
[65,66]	MATLAB-based energy modeling	Model incorporating PV panels, MPPT, buck-boost converter, inverter, and BLDC motor	Improved energy flow, system efficiency, and EV range
[67]	Sensorless BLDC motor + regenerative braking	Control method optimizing energy flow between PV and battery using BLDC + braking energy recovery	30.6% improved energy recovery, extended vehicle range
[68,75]	AI-based MPPT (Artificial Neural Network)	Neural-network-driven MPPT integrated with a boost converter and lithium-ion battery charging system	High efficiency in energy tracking and storage
[69]	Three-phase inverter control	Use of IRAMY20UP60B inverter for propulsion control under varied road conditions	Achieved stable propulsion up to 60 km/h
[70,76]	PV module optimization using 3D LiDAR + simulation	Energy modeling tool using LiDAR point clouds and circuit simulation to predict shading and yield	Quantified shading effects; improved module positioning
[71]	Route-based energy optimization using weather forecasts	Optimal speed profiling and distance planning using PMF and algorithms for the Sasol Solar Challenge	Improved efficiency and ranked 1st nationally in competition
[72]	Predictive control system (multi-vector MPC)	A two-stage model predictive controller for energy use in driving and charging	Increased power density, lower costs, and optimized energy use
[73]	Fuzzy logic control in converted golf carts	Optimization of solar panel dimensions, speed, and weight for energy-efficient operation	Lower battery wear, emission-free transport, and energy savings

These systems must efficiently balance power generation, storage, and consumption, considering factors such as the driving conditions, weather patterns, and user preferences. Intelligent algorithms and predictive technologies can play a significant role in maximizing the benefits of solar energy in vehicular applications. However, key challenges include the decline in MPPT performance under dynamic shading conditions, limited energy storage capacity during times of low solar irradiance, and the complex balance required between vehicle speed, energy consumption, and solar power generation. There are promising research opportunities in developing AI-driven predictive control systems for more intelligent energy management, implementing hybrid energy storage solutions with supercapacitor-battery combinations to enhance power handling, and conducting comprehensive field tests of optimization strategies in diverse environmental conditions to confirm their effectiveness in real-world scenarios. These innovations can significantly improve the practicality and performance of solar-powered electric vehicles.

Table 5. Energy management objectives and optimization purposes in SEVs.

Category	Focus Area	Explanation
Energy Management Objectives	Range Extension	Enhances driving distance by minimizing energy losses and maximizing solar utilization.
	Battery Life Preservation	Prevents degradation through controlled charging, discharging, and thermal management.
	Efficiency Maximization	Optimizes energy conversion across MPPT, DC/DC, inverter, and motor subsystems.
Optimization Purposes	Balancing Power Flow	Coordinates generation, storage, and consumption to avoid inefficiencies and energy loss.
	Adapting to Solar Variability	Responds to changing irradiance due to weather, time, or shading.
	Responding to Driving Dynamics	Adjusts power flow in real time to match acceleration, terrain, and speed demands.
	Mitigating Storage Constraints	Manages limited battery capacity and charging conditions to prevent underuse or overuse.

below is a condensed summary of the energy management objectives and optimization purposes in SEVs.

3.2.3. Lightweight Material

Gorter et al. [77] conducted a comparative analysis of fifteen polymers, including glass fiber-reinforced polymers, to evaluate their feasibility as substitutes for glass in photovoltaic (PV) modules specifically engineered for PV-powered recreational boats. Luo et al. [78] presented a study on the development and reliability assessment of lightweight PV modules designed for VIPV. This study primarily focused on the use of fiber-reinforced polymers, specifically carbon-fiber and glass-fiber-reinforced polymers, to enhance the thermomechanical reliability of these modules. This research highlights the need for lightweight solutions in EVs and discusses the implications of thermal cycling tests on module performance.

Luo et al. [79] explored the strategies of interconnection and encapsulation to enhance the reliability of lightweight modules crucial for future VIPV applications, focusing on resistance to damp heat and mechanical impact. The researchers created lightweight mini modules, weighing approximately 3.45 kg/m², and performed tests for hail impact and damp heat. These tests led to various types of failures, such as solar cell cracks, module delamination, and microcracks in the back sheet. They concluded that the strength of lightweight materials can be improved by performing failure mechanism analysis and adjusting the fiber reinforcement in the back sheet, thus offering guidance for designing lightweight PV modules for next-generation VIPV.

In the study [80], Herr et al. presented a design and concept evaluation of lightweight photovoltaic (PV) systems for vehicle applications, utilizing honeycomb material as a supporting structure. The concept incorporates extendable modules positioned laterally at the upper section of the vehicle, potentially tripling the solar power output during stationary periods. By employing a shell–solid–shell approach, the design process was expedited, reducing the time required for material testing. The researchers established specific load scenarios for vehicle integration in accordance with DIN EN 13561 [81] (a European standard for external blinds) and conducted simulations of a full-size lightweight honeycomb PV module. The experimental results provide valuable insights into the future development and integration of lightweight honeycomb structures in vehicles and other applications.

Most reviewed studies emphasize the importance of precise mechanical integration to ensure durability while optimizing the surface area for solar energy harvesting. The integration of flexible, lightweight solar technologies, as demonstrated by Su et al. [48], alongside the aerodynamic optimization techniques explored by Sekhar et al. [82], indicates a promising future in which solar energy could meet a substantial portion of the energy demands for everyday commuter vehicles, particularly in regions with abundant solar resources.

The development of lightweight materials for photovoltaic (PV) modules and vehicle structures is a critical area of research in SEV technology. Current studies primarily focus on advanced polymers and composite materials, particularly carbon-fiber-reinforced polymers, which offer exceptional strength-to-weight ratios. These materials are being evaluated for their potential to reduce overall vehicle mass while maintaining the structural integrity necessary for safety and performance.

Table 6. Comparison of lightweight materials used in VIPV modules and their impact on vehicle performance.

Material Type	Typical Application in VIPV	Weight Reduction vs. Glass	Impact on Vehicle Performance	Notable Advantages
Glass (Conventional)	Front cover, encapsulation	Baseline (0%)	Heavy; limits placement to roof; increases mass	Good durability, optical clarity
PMMA (Acrylic)	Front sheet	~50%	Lighter, allows for more surface integration	Lightweight, transparent
Glass Fiber-Reinforced Polymer (GFRP)	Front/back sheet, structural support	44–74%	Enables integration on curved/vertical surfaces; reduces energy consumption; maintains strength	High strength-to-weight, hail resistant
Carbon Fiber-Reinforced Polymer (CFRP)	Back sheet, support structure	60–70%	Significant weight savings, enhances range, high mechanical strength	Very strong, durable, lightweight
Honeycomb Composite Structures	Support core (sandwich panels)	Up to 70%	Maximizes surface area, allows deployable panels	Excellent stiffness, ultra-lightweight

provides a summary of different lightweight materials used in VIPV Modules and their impact on vehicles using glass has a baseline for comparison.

One of the primary challenges in selecting materials for SEVs lies in achieving an optimal balance between weight reduction and the maintenance of mechanical strength.

Table 7. Mechanical and economic characteristics of lightweight VIPV materials.

Material Type	Density	Tensile Strength	Flexibility	Durability	Cost	Recyclability
Polymer (e.g., ETFE)	Low	Moderate	High	Moderate to High	Low	Moderate
Composite (CFRP/GFRP)	Moderate	High	Moderate	High	Moderate	Variable (depends on resin)
Thin-film (e.g., CIGS)	Low	Moderate	High	Moderate	High	Low to Moderate

provides a summary of the mechanical and economic characteristics of lightweight materials. Although the use of lighter materials can enhance energy efficiency and extend driving range, they must also adhere to stringent automotive safety standards. This necessitates meticulous engineering of material properties and structural designs to ensure crash safety and long-term durability under operational stresses. Despite these challenges, several opportunities have been identified:

• Development of novel composite materials with self-healing properties. These advanced materials can automatically fix minor damage caused by environmental exposure or mechanical stress, potentially extending the lifespan of components and reducing maintenance requirements. Future studies should investigate hybrid material systems that combine the advantages of multiple material types. For example, combinations of natural fibers with synthetic matrices can offer improved sustainability without compromising performance. Such approaches may provide optimal solutions for balancing weight, cost, and environmental impact. Such innovations could significantly improve the economic viability of SEVs and enhance their long-term performance.
• The exploration of recyclable materials presents a key opportunity to improve the sustainability of SEV technologies. Current research is examining bio-based composites and thermoplastic matrices that are easier to recycle at the end of their life cycle. Life cycle analysis methods should be applied to assess the true sustainability benefits of various material selections. This would enable more informed decisions considering not only operational energy savings but also production impacts and end-of-life recyclability. This approach aligns with circular economic principles and can substantially reduce the environmental impact of vehicle production and disposal.

3.3. Present Application of Photovoltaic in Electric Vehicles

Apart from the popular World Solar Car Challenge, where every solar car participates in a competition, SEVs have been explored for a range of applications in the automotive sector, including cooling systems, disaster relief, and heavy-duty vehicle enhancements.

VIPV can be used to power thermoelectric air-conditioning systems (TEACS) in vehicles. A study by Pang et al. [83] and Kuhnel et al. [84] demonstrated that a TEACS powered by photovoltaics could maintain comfortable temperatures in a small office room under varying thermal loads, suggesting potential applications in vehicle cabins. In this study, mobile PV systems were specifically designed and forecasted for cooling applications in trucks [85,86]. The results indicated that the environmental conditions within the vehicle were significantly improved by the DC air-conditioning system, effectively meeting the thermal comfort requirements for the human body [85,86,87].

Further analysis by Alanis et al. [88] examined the interplay between photovoltaic (PV) modules and the thermodynamic properties of refrigerated trucks. Utilizing a simulation model validated by experimentation, this study focused on the heat produced by solar radiation that was not converted to electricity. The thermal dynamics of truck cargo spaces were analyzed in various European cities, revealing that PV modules induced slight increases in air temperature within refrigerated cargo areas, averaging 0.36 °C in Stockholm, 0.5 °C in Freiburg, and 0.67 °C in Seville. Moreover, this study highlighted that when trucks are in motion, forced convection effectively cools both the solar cells and cargo area, thereby minimizing temperature increases. Importantly, the energy generated by PV systems can offset the extra energy required by refrigeration units to maintain optimal temperatures for perishable goods [73].

Herlambang et al. [89] evaluated another critical aspect of SEV application in thermal management and Internet of Things (IoT). Their study assessed the integration of a thermal management system with Internet of Things (IoT) support in solar electric cars. Tests using six DC fans for air cooling revealed two variations in the battery charging conditions (with 25 and 400 laps of the trimmer constant current step-up charger). The highest recorded step-up charger temperature was 35.75 °C at 57.64 V, and the maximum battery temperature reached 31.75 °C at 57.3 V, both observed under the 25-lap condition.

Another promising application of VIPV is in disaster zones. Araki et al. [90] investigated the potential of VIPV to support utility resilience by considering both physical factors (such as irradiance) and social factors. The energy saved through vehicle-integrated photovoltaics enables the voluntary donation of excess energy, which can help maintain facility resilience during emergencies [28,90]. Their findings concluded that, depending on variables such as climate, population density, and shading conditions, the electricity stored in VIPV systems is sufficient to contribute effectively to disaster relief support [90].

VIPV also offers benefits for heavy-duty applications. Research has assessed the possibility of increasing the mileage of electric vehicles using commercially available solar energy technologies that require minimal investment [91]. For instance, studies have shown that electric vehicles equipped with roof-mounted solar panels can be recharged during parking periods [92]. These photovoltaic modules not only support the car’s propulsion system but also power various accessories, including ventilation, air conditioning, seat heating and interior illumination. The viability of these solutions was demonstrated with and without sun-tracking adjustments for the solar panels. Under specified conditions, calculations indicate that integrated photovoltaic panels can contribute energy equivalent to up to 6.32% of the vehicle’s range on a fully charged battery during peak summer months and up to 1.16% during the least sunny winter months [92].

Another recent study by Parlak et al. [93] showed that PV systems can contribute to fuel conservation in heavy-duty vehicles by offsetting the energy typically consumed by alternators and compressors. In this context, research focused on enhancing battery life has led to the integration of solar power with fuel cells to develop hybrid solar-powered fuel cell electric vehicles. Simulations conducted over 32 scenarios—covering four cities (Berlin, Seville, Istanbul, and Stockholm), four representative months (January, April, July, and October), and two VIPV configurations—demonstrated that incorporating PV panels over all vehicle surfaces significantly improved battery performance. Specifically, a full-surface installation yielded a 7.3% increase in the battery’s current amplitude and a 5.31% reduction in fluctuations, compared with a 3.2% improvement and a 2.04% reduction when panels were installed solely on the roof. In a complementary study conducted in Berlin, Hoeth et al. [94] reported that VIPV extended the vehicle range by 7–14 km per day, which translated into a median annual increase of 2527 km.

Dhar et al. [95] explored the feasibility of employing SPEVs with induction cooking systems as a sustainable solution for India’s travel and tourism challenges. Their electric vehicle mobile food court (EVMFC) concept demonstrated that solar energy could effectively power both vehicle propulsion and cooking operations, thereby reducing reliance on traditional energy sources, lowering greenhouse gas emissions, and offering financial benefits.

A study by Suh [96] assessed the energy potential of a solar-powered electric vehicle driven by a commuter along an expressway. Their study revealed that such a vehicle could generate approximately 1.14 kWh of energy during a daily routine (comprising a 1 h drive and 8 h of parking), equating to roughly 10.6% of the electricity consumed while driving. Furthermore, parking in unshaded areas could boost energy generation by 20%, increasing it to 1.373 kWh.

Table 8. Several applications of SEV.

Applications	References
Cooling Application for trucks and Thermal Management	[83,84,88,89]
Increasing mileage for Heavy Duty	[92]
Disaster Relief Support	[90]
Fuel Conservation and Extended range	[93,94]
Induction Cooking System	[95]

shows the different application areas of SEV and their references.

The integration of photovoltaic (PV) technology into electric vehicles (EVs) has progressed beyond mere propulsion, and now encompasses specialized applications such as thermoelectric cooling systems for refrigerated transport, emergency power provision in disaster relief scenarios, and auxiliary energy generation for heavy-duty vehicles. Although these applications demonstrate the flexibility of solar electric vehicles, they face notable challenges, such as limited energy contribution (usually supplying only 5–10% of total energy requirements), thermal management issues in PV-equipped refrigerated trucks, and difficulties in scaling solutions for mainstream passenger vehicles. Despite these challenges, there are significant opportunities for the adoption of VIPVs. These include the implementation of solar-powered public transit systems (e.g., buses with expanded PV surfaces), exploration of vehicle-to-grid capabilities to facilitate energy sharing during power outages, and the development of solar-powered auxiliary systems such as heating, ventilation, and air conditioning, Internet of Things-based monitoring sensors, and onboard electronics, to reduce reliance on primary battery storage. These advancements have the potential to improve energy efficiency and extend the operational range of solar-assisted EVs beyond their current niche applications.

3.4. Weather Conditions and Shading Effects

Solar electric vehicles face several weather-related challenges. For example, shading effects and adverse weather conditions in regions with low sunlight can significantly affect performance [87,97].

The reviewed studies examined this topic from various perspectives. For instance, Jaikh et al. [98] and Salomon et al. [99] conducted simulations to evaluate the performance of SEV under diverse weather conditions. Jaikh et al. [98] developed a simulation tool to address the limited charging access and driving range of SPEVs. Their tool evaluates various factors influencing a vehicle’s photovoltaic (PV) yield by comparing different geographical areas, vehicle classes, surface types, weather conditions, driving/parking cycles, shading scenarios, and electrical configurations. The key findings from both papers are as follows:

• The roof is the most effective zone for PV integration, whereas doors are particularly beneficial during winter.
• High-efficiency PV modules (exceeding 20%) on the roof can supply more than 20% of the monthly mileage from March to September.
• With full-vehicle PV coverage, approximately 25% of a 1000 km monthly mileage is achievable, which drops to 16% when door modules are excluded.
• A 10% increase in PV efficiency may reduce the required charging energy by 12–16%.
• Partial shading across series-connected modules may reduce energy capture by 5–10% [100].

Baek et al. in two separate studies [86,100] had another approach for quantifying shading effects. The authors investigated the shading of parking spaces on a university campus by capturing hemispherical images. They introduced a Parking Space Suitability Index to quantify the reduction in solar insolation caused by shading during operational hours. Their analysis, which utilized a genetic algorithm on 69 parking spaces at Pukyong National University, revealed consistent shading effects in summer (spring and summer) and variations in shading during winter mornings and afternoons, suggesting that parking strategies should adapt to seasonal and temporal differences. Sovetkin et al. [101] explored how non-uniform irradiation in PV modules leads to energy losses due to current irradiation nonuniformity and topography effects. Their study, which considered both a small delivery truck and a commercial passenger vehicle, highlighted that topography is the primary factor affecting irradiation distribution and observed that vehicle surface orientation and curvature are secondary influences. However, in residential areas, vertical surfaces can experience up to 35% less irradiation on the lower parts than on the top.

Araki et al. [102] compared vehicle-integrated PV systems to standard PV installations by modeling solar irradiance, considering the random distribution of shading objects and the curved surface of vehicles. Their one-year measurement campaign using multiple pyranometers validated the model for both the car roof and body. In another study, the authors used advanced MPPT algorithms to track irradiance. Rizzo et al. [103] combined an artificial neural network with a hill-climbing method to propose an MPPT algorithm. This algorithm quickly adapts to fast-changing partial shading conditions with only a limited set of current measurements, thereby minimizing the time required to reach the optimal operating condition. Their study noted that simpler neural network structures are sufficient for slowly changing shading conditions, whereas more complex configurations are required for urban, fast-changing environments.

Wetzel et al. [104] conducted in-motion measurements of incident irradiance on vehicles, demonstrating that weather conditions predominantly affect the roof, whereas the sides are more influenced by seasonal changes. The authors also noted that changes in irradiance mostly occur below 1 Hz, although higher frequency variations (up to 100 Hz) are possible in sunny weather, affecting the MPPT system design. Samadi et al. [47] categorized the performance of vehicle-integrated PV systems into three groups: installation location, solar cell properties, and environmental factors. They reported that the irradiance on a van’s roof can be between 1.09 and 3.85 times higher than that on its sides, depending on the weather and seasonal conditions.

Gaspar et al. [35] examined the “parking dilemma”, which involves the trade-off between optimizing solar charging and the resultant increase in cabin temperature, which necessitates additional air conditioning. Their research, conducted in Lisbon, Portugal, determined that a photovoltaic (PV) system with a capacity of 0.5 kWp requires a minimum of two hours of solar exposure to achieve net-positive charging. Furthermore, systems with capacities exceeding 0.8 kWp consistently produced favorable outcomes.

Mobarak et al. [105] proposed a large-scale solar EV concept with low-cost, flexible, and thin-film solar cells integrated onto the steel of all upward-facing vehicle body panels as a viable solution to mitigate EV charging, range concerns, and the high cost and solar power intermittency of individual residential rooftop solar installations. This study models the effect of panel tilt and partial shading on the solar energy capture of 150 drivers to analyze the grid, driver, and environmental benefits in Los Angeles and Detroit over the course of a full year. The simulations predicted net annual vehicle energy use reductions of 21.5% in LA and 17.5% in Detroit for average cloud conditions compared to a non-solar EV.

Kuhnel [84] developed an algorithm to forecast annual power distribution and solar energy yield along a given track, using high-resolution meteorological data (ambient temperature, wind speed, global horizontal irradiance) in a German use case. The study revealed that the efficiency of VIPV modules benefits significantly from head wind cooling, resulting in superior performance under motion compared with stationary PV installations. For commercial semi-trailer lorries, the potential annual energy yield was estimated to be 3–7 MWh, with head wind cooling contributing an additional 20–75 kWh per trailer annually.

Susanne et al. [106] conducted a series of experiments on three distinct types of solar cells to evaluate their responses in terms of voltage, current, and efficiency under varying degrees of shading, both horizontally and vertically. This study underscored the critical importance of minimizing shading on solar panels and selecting panel types that exhibit greater resilience when shading is unavoidable. Figure 8, Figure 9, Figure 10, Figure 11, Figure 12 and Figure 13 below present graphs illustrate the impact of shading percentage on the performance of three types of solar panels: CdTe, Poly-Si, and Mono-Si. The performance metrics analyzed included open-circuit voltage (Voc), short-circuit current (Isc), and efficiency (%). Figure 8, Figure 9 and Figure 10 display the results for horizontal shading, while Figure 11, Figure 12 and Figure 13 depict the results for vertical shading. The graphs indicate that all three solar panel types experienced significant performance losses as shading increased, with the most pronounced declines occurring at low to moderate shading levels. Mono-Si panels exhibit somewhat greater resilience; however, no technology is immune to heavy shading effects.

Based on the above discussion, the weather factors affecting the efficiency of PV systems in solar electric vehicles can be categorized as follows:

• Partial shading represents a significant technical challenge for PV performance in urban environments. The series configuration of conventional PV modules renders them particularly vulnerable to uneven illumination, where shaded cells can substantially reduce the output of the entire array. Experimental studies have demonstrated that even modest shading covering 15–20% of a module’s surface area typically results in 5–10% power loss, with the exact impact depending on several factors such as the spatial distribution of shadows, module interconnection layout, and effectiveness of the MPPT system. This issue is particularly pronounced in urban canyons and streets lined with trees, where dynamic shading patterns are common.
• Seasonal and geographic variability introduces additional complexity to PV performance in SEVs. The availability of solar resources is significantly influenced by both latitude and season, with temperate regions experiencing particularly notable variations between the summer and winter. Atmospheric conditions, including aerosol concentrations, humidity levels, and cloud cover patterns, further modify the intensity and spectral characteristics of incoming sunlight. Studies have demonstrated that these combined effects can lead to annual energy yield variations of 30–50% across different climate zones, necessitating a region-specific design approach for optimal performance.

However, these challenges present new research opportunities. For example, when addressing seasonal and geographic variations, it is essential to consider comprehensive strategies that aim to convert SEVs into climate-resilient energy-harvesting systems, ensuring that they maintain peak performance under diverse weather conditions during the design phase. One method of achieving this is incorporating a “multi-stage operation and recovery strategy” for improving system resilience under environmental fluctuations and photovoltaic power generation uncertainty [107]. Additionally, researchers should emphasize the integration of intelligent system design and adaptive technologies in solar electric vehicles. With recent advancements in Artificial Intelligence (AI) and Machine Learning (ML), there is potential to utilize advanced machine learning algorithms and develop weather-based AI agents to optimize parking strategies by analyzing real-time irradiance forecasts, three-dimensional (3D) urban solar maps, and vehicle usage patterns. These smart systems can boost daily energy collection compared to traditional parking methods using predictive technology.

The ultimate objective is to develop PV integration strategies that are simultaneously environmentally adaptive, energy-optimized, and cost-effective, thereby enabling the widespread commercial deployment of solar electric vehicle technology. Progress in this field requires interdisciplinary collaboration among photovoltaic researchers, automotive engineers, and climate scientists to address the complex challenges at the intersection of these disciplines.

3.5. Economic Analysis and Market Viability

Although solar electric vehicles (SEVs) are becoming increasingly technologically feasible, their widespread adoption depends on their economic viability. One of the central financial challenges is balancing the high initial purchase price with the promise of lower long-term operational costs [41]. The upfront cost remains the primary economic barrier, largely because of the expensive components and manufacturing requirements. High-efficiency photovoltaic (PV) cells, which are significantly more expensive than standard residential panels, contribute to this premium. Additionally, lightweight composite materials are required to counterbalance the added weight of PV panels, and the seamless integration of these systems into vehicle structures requires complex and costly production processes. For instance, the Lightyear 0, an early entrant in the SEV market, was projected to cost approximately €250,000, effectively restricting it to the luxury segment and rendering it inaccessible to the average consumer [108].

Table 9. Comparative economic analysis of VIPV vehicles.

Manufacturer/Model	Payback Period (Estimated)	Annual Energy Savings	Estimated Cost	Commercialization Stage	Economic Benefits	Adoption Barriers
Lightyear 0/Lightyear One	40+ years	$1000–2000	~$290,000 (Lightyear 0); future models projected at ~$45,000	Limited production/Lightyear 2 in development	Solar-only short commutes possible; grid-independence potential	High upfront cost; niche luxury market; production halted temporarily
Sono Motors Sion	8–12 years	$800–1200	~$34,500 (before shutdown)	canceled (2023)	Low-cost urban solar mobility; shared energy model	Financial insolvency; limited range; market confidence issues
Toyota Prius PHV Solar Edition	15–20 years	$200–400	~$35,000 (in Japan)	Mass production (Japan only)	Extended range with minimal solar tech; mature EV platform	Limited solar yield; available only in Japan; lacks full solar propulsion
Hyundai Sonata Hybrid Solar Roof	25.4–35.6 years	$150–300	~$27,750 (base model)	Commercialized (selected markets)	Slightly reduced charging needs; minimal premium cost	Marginal solar gain; not a full VIPV system; limited public awareness

presents a comparative economic analysis of notable VIPV-equipped vehicles developed by Lightyear, Sono Motors, Toyota, and Hyundai. The table highlights differences in annual energy savings, estimated payback period, vehicle cost, commercialization status, and key adoption barriers across various market segments.

Despite their steep initial costs, SEVs offer potential economic advantages through a reduced total cost of ownership (TCO) [41]. By harnessing solar energy directly, SEVs reduce dependence on grid electricity, which is often subject to price fluctuations. In sun-rich regions, where electricity prices are high, this can translate to substantial savings over time. Suh [96] suggested that for an average commuter, solar-generated energy can cover more than 10% of daily travel needs, significantly reducing “fueling” costs. This benefit not only reduces long-term operating expenses but also shortens the payback period required to recoup the initial investment in vehicle-integrated photovoltaic (VIPV) technology.

The payback period is another crucial economic metric for both individual consumers and fleet operators, as it determines how quickly the additional investment in solar integration can be recovered by the consumer. This period varies significantly based on several factors, including solar availability, daily driving distance, electricity cost, and PV system efficiency. For example, Mobarak et al. [105] found that in sunny regions, such as Los Angeles, VIPV systems could reduce annual vehicle energy use by over 21%, resulting in a faster return on investment than in cloudier areas, such as Detroit, where the reduction was approximately 17.5%. Commercial vehicles, such as delivery vans and refrigerated trucks, often have a stronger economic case for VIPV because of their constant operation and high energy demands as discussed by [61,109]. Even modest solar contributions in these scenarios can lead to notable annual savings, making this technology particularly attractive to fleet managers.

Looking forward, the widespread adoption of SEVs could deliver significant macroeconomic benefits. As decentralized energy producers, SEVs can alleviate the pressure on the central electrical grid, potentially delaying the need for costly grid infrastructure upgrades. Integration with Vehicle-to-Grid (V2G) systems could enable SEVs to act as distributed energy resources, offering grid stabilization services and even generating income for vehicle owners. This evolution can transform vehicles from passive transportation tools into active components of the energy ecosystem, redefining the economics of car ownership.

However, for SEVs to achieve mainstream adoption, the cost of integrated PV systems must continue to decline, and scalable manufacturing methods must be developed. Policy support is likely to play a pivotal role in this regard. Government incentives, such as tax credits or subsidies that acknowledge the dual function of SEVs as both clean transport and distributed energy generators, could help close the cost gap and expedite their market entry.

4. Conclusions

This comprehensive review systematically examined the evolution and current state of solar electric vehicles and vehicle-integrated photovoltaics, revealing both significant progress and persistent challenges in this transformative field. The analysis demonstrates that although substantial advancements have been made in photovoltaic efficiency, lightweight materials, and integration techniques, several critical barriers remain before SEVs can achieve widespread adoption. The following key challenges were identified:

• Energy Yield Optimization: Consistent energy generation under varying weather, especially in winter or low-sunlight areas, is a significant barrier. Enhancing photovoltaic performance under suboptimal conditions is essential for reliable output.
• Economic Viability and Energy Contribution: Current solar technologies often supplement rather than serve as primary power sources in vehicles. For SEVs to be viable, further research is needed to enhance economic efficiency and real-world energy contribution of solar-integrated systems.
• Standardized Testing Protocols: Without unified testing standards across climate zones and usage scenarios, assessing real-world performance accurately is limited. Establishing standardized evaluation methods is crucial for benchmarking advancements.

To address these barriers, future research must focus on three pivotal areas: first, developing AI-driven energy management systems is critical. These systems should employ predictive algorithms using real-time solar irradiance forecasting (potentially using 3D urban solar maps), vehicle usage patterns, and battery state-of-health to optimize power flow between PV array, battery storage, and electric motor, including integration with regenerative braking systems to maximize energy recovery. Second, implementing innovative material solutions is paramount. This includes advancing next-generation PV cell technologies (such as perovskite-silicon tandem cells, aiming for efficiencies exceeding 30%), developing durable, flexible encapsulation materials resistant to environmental degradation and mechanical stress, utilizing cost-effective, ultra-lightweight structural composites to offset PV component weight without compromising vehicle safety. Third, adaptive SEV and VIPV designs must be created. This involves designing PV integration for various vehicle typologies (e.g., passenger cars, commercial trucks, and public transport buses) and their operational demands, potentially incorporating features such as dynamically reconfigurable PV surfaces or solar skins that maximize exposed surface area for energy harvesting without hindering vehicle functionality.

To accelerate the commercialization and market penetration of SEVs and VIPV, the following actions are recommended:

• Establishing international research collaborations to develop unified testing standards and share best practices. This will foster unified testing standards (building initiatives such as IEC TC 82 PT 600) for VIPV performance, safety, and reliability, and facilitate sharing of manufacturing and integration practices.
• Investing in fundamental research on next-generation photovoltaic materials for vehicular applications. The focus should be on materials engineered for vehicles, targeting high conversion efficiencies under variable light conditions, enhanced durability, low degradation rates, cost-effective mass production, and sustainable lifecycle management.
• Developing simulation tools that accurately predict system performance under diverse conditions. These tools should predict dynamic energy yields, thermal management effects on PV performance, and impact on vehicle range and battery longevity under various geographic and climatic scenarios, aiding design optimization and reducing costs.
• Exploring hybrid solutions combining solar power with other renewable sources to enhance system reliability. This includes optimizing synergy between solar generation, advanced battery technologies (e.g., solid-state batteries), enhanced regenerative braking systems, and other onboard energy harvesting methods to improve reliability, efficiency, and range.

These efforts, combined with continued technological innovation and supportive policy frameworks, will be crucial in realizing the full potential of solar-powered transportation as a sustainable solution for the future of humanity. As the transportation sector continues its transition toward cleaner alternatives, SEVs and VIPV represent promising pathways for achieving global carbon reduction targets while addressing growing mobility needs.