Powertrain of a Solar electric vehicle
Shriya Pargi Manipal Institute of Technology
Computer science and Engineering Udupi, Karnataka
(AI&ML) mailto:shriyapargi123@gmail.com
Abstract—The technology of electrified vehicles is considered c) Weight and Cost: Achieving high solar
a promising approach for improving energy efficiency and conversion efficiency while maintaining low
minimizing emissions. Solar electric vehicles (SEV) are weight and cost.
significantly advancing the adoption of environmentally 3) Emerging Trends: Development of more flexible and
friendly transportation as they use solar power to ease the lightweight PV materials, bifacial solar cells that can capture
demand on batteries within electric vehicles. This article
provides an overview of the major components that constitute
reflected light, and the exploration of perovskite-based solar
the powertrain of SEVs such as solar panel arrays, energy cells for improved performance.
storage devices, electric propulsion systems, power B. Power Electronics
conditioning equipment, and energy control units. They are all
important considering the need to optimize the efficacy and 1) Functionality: This subsystem is responsible for
range of SEVs for low emission environmentally friendly conditioning the DC power generated by the solar
transportation options. panels to a usable form. It includes:
a) Maximum Power Point Tracking
Keywords—solar, electric vehicles, powertrain, sustainable (MPPT) Circuits: These optimize
power output from the panels
I. INTRODUCTION dynamically irrespective of operating
Photovoltaic (PV) technology, particularly solar cells, conditions.
holds significant potential as a renewable energy source for b) DC-DC Converters: These transform
road transportation. When used as an additional energy the variable voltage from the solar
source for electric vehicles (EVs), solar cells can partially array to a stable voltage suitable for
replace energy typically sourced from the grid or charging charging the battery system and
stations. A key aspect of integrating solar energy into powering the electric motor.
vehicles is the incorporation of a PV system within the c) Inverters: Converting DC power to
vehicle's powertrain. This integration involves two main AC to drive the electric motor
tasks: designing the topology of an EV powertrain that (depending on motor type).
accommodates a PV system and regulating the energy flows 2) Challenges: Minimizing power losses during
within the PV-augmented powertrain. These challenges can conversion, ensuring high efficiency, managing
be further divided into two categories: addressing the specific heat dissipation, and reducing the size and weight
requirements of the EV powertrain design and considering of these components.
the ambient operating conditions of the PV system. The 3) Emerging Trends: Use of wide-bandgap
design and control of the PV system depend on how its
semiconductors (e.g., GaN, SiC) for more efficient
energy is intended to be utilized, whether for powering
and compact power electronics, advanced control
auxiliary systems, storing energy for vehicle propulsion, or
both. algorithms for enhanced performance, and
integration of power electronic functions.
C. Energy Storage System (ESS):
II. CORE COMPONENTS 1) Technology: The ESS, typically a lithium-ion
A. Solar Photo-voltic (PV) Arrays battery pack, stores the excess energy generated by
the solar panels and provides power to the motor
1) Technology: The primary energy source for SEVs is when solar input is insufficient.
derived from solar PV panels typically based on silicon 2) Challenges:
(crystalline or thin-film). These panels are often integrated a) Weight and Volume: Balancing required
into the vehicle's roof, hood, or even side panels, energy capacity with the need for
maximizing their exposure to sunlight. lightweight, compact systems.
2) Challenges: b) Energy Density and Charge/Discharge
a) Surface Integration: Balancing aerodynamic Rate: Improving battery energy density
considerations, aesthetics, structural integrity, and charge rate to enable longer ranges
and efficiency of solar panels integrated into and faster recharging.
vehicle bodies. c) Thermal Management: Effectively
b) Efficiency and degradation: Overcoming managing battery temperature during
variations in light intensity, temperature, and charging/discharging cycles to ensure
shading, as well as issues of solar cell safety and longevity.
degradation over time. 3) Emerging Trends: Development of solid-state
batteries for increased energy density and safety,
alternative battery chemistries, advanced battery
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management systems (BMS), and the integration of required level, ensuring compatibility and efficient energy
ultracapacitors to improve instantaneous power flow.
delivery.
Fig. 1. Schematic of EV electrical and control
D. Electric Motor:
1) Technology: SEVs typically employ permanent V. ENVIRONMENTAL AND OPERATIONAL FACTORS
magnet synchronous motors (PMSM) or induction The primary parameters influencing the operation of a
motors due to their high efficiency and power PV system are solar irradiance (SI) and the temperature of
density. the cells. Solar irradiance, which is the amount of sunlight
2) Challenges: Optimizing motor efficiency across a incident on the PV surface, and the temperature, which is
wide range of speeds and loads, minimizing weight influenced by factors such as irradiance, system design, and
and size, and designing effective cooling systems. vehicle speed, are essential in determining the system's
3) Emerging Trends: Development of more efficient performance. Temperature can affect key parameters of the
and compact motor designs, advanced materials for PV cells, including their efficiency and voltage. While these
magnetic components, and integration of motor factors are vital for analyzing PV system design and
control into single modules. operation, they are beyond the scope of this article and will
E. Vehicle Control Unit (VCU): be explored in further detail in subsequent studies.
1) Functionality: The VCU acts as the brain of the
powertrain, coordinating the operation of all VI. CHALLENGES OF INTEGRATING THE SEV POWERTRAIN
subsystems. It manages power flow, optimizes
A. Limited Solar Energy Generation
energy consumption, and implements advanced
driving assistance system (ADAS) functionalities. Despite optimal placement of solar panels, the amount of
2) Challenges: Developing adaptive and predictive energy generated by solar power is constrained by the
algorithms for optimal power utilization, ensuring limited surface area available on the vehicle and the
reliable and accurate control, and implementing fluctuating intensity of solar radiation. This limitation
advanced safety features. necessitates the use of supplementary energy sources to
3) Emerging Trends: Integration of AI and machine ensure consistent power supply.
learning for real-time optimization, improved B. Impact on Weight and Aerodynamics
connectivity, and cyber-security enhancements.
The addition of solar panels and associated hardware can
increase the overall weight of the vehicle, which is a critical
factor for electric vehicles. Moreover, integrating solar
III. POWERTRAIN DESIGN AND INTEGRATION panels may disrupt the vehicle's aerodynamic profile,
potentially increasing energy consumption during operation
A typical electrically driven passenger vehicle, whether pure
and reducing overall efficiency.
electric or hybrid, features a high-voltage (HV) traction
system, with the main energy storage being the traction C. High Component Costs
battery. If the PV system is to supply energy to this battery, High-efficiency solar panels and advanced battery
an appropriate interface must be developed. However, the technology required for SEVs come with a substantial cost.
voltage of a PV system suitable for passenger vehicles is Reducing the cost of these components is essential for
significantly lower than that of the traction system. Due to making SEVs more accessible and promoting their
space limitations on vehicle surfaces, such as the roof, widespread adoption in the market.
which can accommodate only a limited number of solar
cells, the nominal voltage of these cells is typically around D. Variability in Solar Power Availability
0.5–0.6 V. In contrast, the voltage of a traction system Since solar power generation is dependent on sunlight, the
ranges from 200 to 400 V. This creates a significant voltage availability of energy fluctuates throughout the day and
disparity—often in the range of 10 to 20 times—requiring under different weather conditions. This intermittent nature
the integration of an advanced DC/DC converter. The of solar power introduces challenges for maintaining reliable
efficiency of this converter becomes a crucial factor in and consistent performance, especially under low light or
ensuring the system's performance. cloudy conditions.
E. Thermal Management Challenges
IV. INTERFACE BETWEEN PV SYSTEM AND Solar panels and battery systems generate significant heat
TRACTION BATTERY during operation, which can affect their efficiency and
For the PV system to be effectively integrated into the longevity. Effective thermal management solutions are
vehicle’s powertrain, a suitable interface must be created needed to prevent overheating, ensure optimal performance,
between the PV system and the traction battery. This and protect components from potential damage.
interface ensures the seamless transfer of power between the F. Efficiency of Power Electronics
solar cells and the battery. Since the PV system typically
operates at a much lower voltage than the traction system, a The conversion and transmission of electricity from solar
DC/DC converter is necessary to step up the voltage to the panels to the vehicle’s battery and powertrain require highly
efficient power electronics. These devices must minimize
energy losses to ensure that the maximum amount of solar intelligently manage energy flow within the powertrain.
energy is utilized for vehicle propulsion and operation. These systems optimize solar energy intake and battery
usage according to different driving modes, weather
conditions, and navigation needs.
VII. ADVANCEMENTS AND FUTURE DIRECTIONS
G. Vehicle-to-Grid (V2G) Capabilities
A. High-Efficiency Solar Cells Future SEVs may be capable of not only using solar energy
New materials and advanced device architectures for but also feeding excess power back to the grid, enhancing
photovoltaic (PV) cells, such as perovskite and tandem cells, their contribution to renewable energy generation and grid
are being developed to achieve higher efficiency levels stability.
while reducing production costs.
H. Integration with Advanced Driver-Assistance Systems
B. Flexible and Lightweight Solar Panels (ADAS)
Innovations in thin-film solar cells are enabling their Sophisticated sensor systems and advanced algorithms could
integration onto curved vehicle surfaces, offering a lighter allow SEVs to anticipate energy needs, optimize power
alternative to traditional panels and further reducing the consumption, and manage charging requirements more
vehicle’s overall weight. effectively, further enhancing the vehicle's energy efficiency
and driving experience.
C. Advanced Battery Technologies
The development of solid-state batteries promises to offer
higher energy densities, faster charging capabilities, and
enhanced safety features, improving the overall energy ACKNOWLEDGMENTS
storage system in SEVs. I would like to express sincere gratitude towards the
SolarMobil team for giving me the opportunity to work on
D. Enhanced MPPT (Maximum Power Point Tracking)
this project.
Algorithms
More intelligent and adaptive MPPT algorithms are being REFERENCES
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