A solar roof may sound like an ideal accessory for an electric vehicle: park outside, collect energy during the day and avoid plugging in. In practice, however, the limited area of a car roof produces only a small amount of electricity compared with the energy required to drive a modern EV.
The EPA estimates that the median model-year 2025 electric vehicle uses 39 kWh per 100 miles, or about 390 Wh per mile. A 400-watt solar array covering roughly 22 square feet could generate 1.6 kWh after four hours at its rated output, before charging losses. That would provide approximately four miles of range at the EPA's median consumption rate.
Actual production can be lower because of shade, clouds, heat and poor parking angles. Increasing the size of the array also creates trade-offs. Additional panels and supporting hardware add weight, which makes the motors use more energy, while panels mounted above the body can increase aerodynamic drag. Flush-mounted panels reduce the drag penalty but cannot solve the limited roof area.
Automakers and startups are exploring ways to collect more sunlight without creating a permanent aerodynamic problem. Nissan's Ao-Solar Extender prototype for the Sakura EV produces up to 300 watts with the panel retracted while driving. When parked, a second panel extends over the windshield, raising output to 500 watts.
Another approach is to build a much more efficient and unconventional vehicle. Aptera's three-wheeled EV has two seats, a teardrop-shaped body and lightweight composite construction. The company is targeting consumption of 100 Wh per mile, roughly one-quarter of the EPA's median figure for a 2025 EV.
In July testing in Southern California, TÜV Rheinland measured 4.23 kWh delivered to an Aptera prototype's battery while it remained parked, untouched and with its hatch closed. At Aptera's targeted efficiency, that amount would represent about 42 miles of range. The result measures electricity collected rather than the distance the vehicle could ultimately drive, and real-world use would still depend on factors such as garage parking, cloudy weather and longer journeys.
Solar roofs are more practical on recreational vehicles, where rooftop panels can power lights, fans and refrigerators rather than propel the vehicle. Conventional EVs face a much larger energy demand, making solar panels better suited to reducing the frequency of charging than eliminating it.
The commercial challenge is also significant. Lightyear suspended production of its first solar EV in January 2023, shortly after deliveries began, and its operating company, Atlas Technologies, entered bankruptcy days later. Aptera has set a target price of $40,000 for its Launch Edition. In an October 1 SEC filing, the company said it planned to build its first 40 production vehicles by the end of 2026 and begin customer deliveries in early 2027, subject to financing, supplier performance and regulatory approvals.
Sources: Engadget.