Powered directly by the sun, electric vehicles (EVs) equipped with solar panels offer the promise of a cleaner, greener zero-emissions future. Effectively integrating solar panels, however, has proven difficult for many automotive companies. This article discusses key challenges, from cost and efficiency to area and weight limitations. It also explores how innovative designs are helping engineers develop a new generation of sustainable EVs, such as the solar-assisted, three-wheeled Aptera.
The evolution of EV and HEV solar solutions
Some of the first EVs and hybrid electric vehicles (HEVs) were equipped with optional solar panels to help recharge batteries for secondary systems, including climate control and lighting. For example, the first-generation Nissan LEAF EV offered a small solar panel on the rear spoiler to supplement the charge of its 12-volt battery. Toyota introduced a similar solar solution for its second-generation Prius HEV. Subsequently, it debuted a more comprehensive, integrated rooftop solar option (in Europe and Japan) to incrementally boost the range of its fourth-generation hybrid.
Figure 1. Toyota’s fifth-generation, 2023 Prius HEV. (Image: MotorTrend)
Launched in 2023, Toyota’s fifth-generation Prius (Figure 1) includes an optional solar roof that powers the vehicle’s air conditioner and adds four miles of range per eight-hour charge. Similarly, the Hyundai Ioniq 5’s optional solar roof panels provide three extra miles of range per day. In comparison, the SolarSky panels on the roof of Fisker’s Ocean Extreme and Ocean One produce four to five emissions-free miles in optimal conditions.
Many companies also sell portable solar covers and kits for EVs and gas or diesel-powered vehicles. Worksport, for example, recently announced the development of a specialized Ford F-150 SOLIS solar cover (Figure 2) for off-grid use.
Figure 2. The Ford F-150 Lightning, equipped with a specialized SOLIS solar cover fitted over the EV’s cargo bed. (Image: Electrek)
The company plans to assess the cover’s compatibility with the F-150 Lightning’s charging system and its potential to add up to 10 miles of range under optimal conditions.
Additionally, EV Solar Kits is developing an 1100W array that charges auxiliary batteries and attaches to EV rooftops with a universal mounting system. Sono Motors, which first introduced its solar-assisted Sion EV prototype in 2021, now focuses on designing solar panel kits to help power diesel buses and refrigerated trailer climate control systems. Similarly, Lightyear recently pivoted from developing its own solar-powered EV to manufacturing solar roofs for other companies.
Navigating EV solar panel design limitations
Despite their inclusion in select EV models, automotive solar panels still cannot consistently generate high power levels or significantly extend driving range due to:
- Integration angles: Solar panels operate most efficiently when installed at a slight angle (~30 degrees) rather than integrated perpendicularly on an EV roof.
- Area: Limited available surface area restricts solar panel size and constrains power generation. Moreover, the added weight of solar panels may impact vehicle efficiency and performance.
- Weather: Rain, snow, and overcast skies significantly reduce charging efficiency, leading to unpredictable energy generation and minimal range extension.
Although drivers won’t be unplugging their EVs from the grid anytime soon, Miguel Brito of the Dom Luiz Institute sees solar panel infrastructure as an EV standard by 2030.
Dan Kammen, an energy professor at UC Berkeley, expresses similar sentiments, observing that the cost of EV solar panel production and integration will continue to decline over time.
Concurrently, the development of new solar technology, driven by artificial intelligence (AI) and machine learning (ML), is also expected to accelerate EV solar integration and adoption. For example, scientists at the Odisha University of Technology and Research in India recently designed a direct-current electric motor powered by a photovoltaic array that achieves 88% efficiency by leveraging advanced ML algorithms and regenerative braking.
The future of solar-powered vehicles
Sono Motors and Lightyear have seemingly shifted their focus to manufacturing solar panels rather than solar-assisted EVs. However, Aptera remains on track with developing and producing its three-wheeled solar EV.
Figure 3. The solar-assisted Aptera EV, showcasing diamond shaped solar panels that deliver ~700W of supplemental, continuous charging power. (Image: Aptera)
Traveling up to 1,000 miles on a single charge, the Aptera integrates solar panels on its sleek hood, roof, and rear hatch — adding up to 40 miles of solar-powered driving daily. Constructed with lightweight composite materials, the Aptera features an aerodynamic undercarriage that significantly reduces air drag, helping the EV accelerate from 0 to 60 mph in just four seconds.
Notably, low-speed vehicle (LSV) manufacturer Wink Motors is already selling two specialized EV models equipped with (attached) solar panels: the $10,995 Sprout Solar and the $12,995 Mark 2 Solar (Figure 4).
Figure 4. The Mark 2 Solar LSV. (Image: Wink Motors)
Summary
Powered directly by the sun, EVs equipped with integrated solar panels provide a glimpse of a more sustainable zero-emissions future. Despite their inclusion in select EV models, most automotive solar panels still can’t consistently generate high power levels or significantly extend driving ranges due to area, installation, and weather constraints.
Nevertheless, emerging technologies and more affordable solar panels are already accelerating EV solar adoption alongside the design of new vehicles such as the solar-assisted Aptera.
References
- Why Solar Electric Vehicles Might be the Next Generation of EVs, CNBC
- Is the Solar-Powered Electric Vehicle Revolution Imminent?, MakeUseOf
- Where Are All the Solar-Powered Cars?, IEEE Spectrum
- How Solar Roofs Are Being Used to Power Electric Cars, Bloomberg
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