Created by college students, an electric car driven entirely by solar energy! 17.5m2 solar panels, two kilowatts of power, full battery life of 600 kilometers...
Solar powered electric car
At this stage, when we talk about "zero carbon emissions", we don't actually mean that there is no carbon dioxide emission, but that the carbon dioxide emitted can be offset by natural means such as tree planting with an equivalent amount of oxygen to achieve a balance. So, is there a way to make some major sources of carbon emissions, such as cars, achieve zero true carbon emissions?
Recently, an electric car built by 22 students from the Eindhoven University of Technology in the Netherlands became popular on the Internet. According to the introduction, the car was named "Stella Vita". It is a double camper van including a double bed, sofa, kitchen area, etc. It is also equipped with a bathroom with shower, sink and toilet.
Source: Solar Team Eindhoven
The Stella Vita electric car is powered entirely by solar energy and does not require any other fuel. At present, it has driven about 2,000 kilometers in Europe, and their goal is to reach 3,000 kilometers. As shown in the picture above, there are three solar panels above the Stella Vit electric vehicle, covering a total area of 17.5 square meters, two of which are folded and can be unfolded when parking, and an 8.8 square meter solar panel when driving on the road Charge. When the battery panels on both sides are recycled, the Stella Vit electric car is more like a traditional car, as shown in the figure below.
Source: Solar Team Eindhoven
Stella series solar car
Seeing Stella Vit, many practitioners must have guessed which team it is at the first time. This Internet celebrity car is not the team’s first work. As early as 2013, the team announced the first generation of Stella solar electric car and won the first place in the Cruiser Class of the World Solar Challenge held in Australia.
Currently, on the Solar Team Eindhoven website, there are already several Stella series electric vehicles, namely Stella, Stella Lux, Stella Vie, Stella Era and Stella Vita. According to the introduction of Solar Team Eindhoven, Stella is the world's first solar-powered family car; Stella Lux is a family car with energy harvesting function, which generates more energy than it consumes in a year; Stella Vie The first solar-powered family car that can accommodate 5 people; Stella Era is a comfortable self-driving family car; Stella Vita is a self-sufficient "house on wheels".
Tijn Ter Horst, a member of the Eindhoven 2021 solar team, said: "The main goal is to truly inspire people, the market and society to accelerate the transition to a more sustainable future. What we are trying to do is to show people and companies what is already possible."
The Stella Vita project started in September 2020, and the design and manufacturing was completed in March 2021. In September this year, Stella Vita obtained a license for use on public roads, and started a journey to Europe at the end of September. Stella Vita's planned itinerary is to start from Eindhoven to Tarifa, the southernmost point of Spain. The total distance is 3,000 kilometers and is completely powered by solar energy to prove the feasibility of the project.
In terms of body performance, Stella Vita is equipped with a lithium-ion battery with a capacity of 60 kWh. After the vehicle is fully charged, the cruising range can reach 600 kilometers. If the whole journey is sunny, the maximum cruising range can reach 730 kilometers.
Stella Vita breaks through the design boundaries of traditional cars. It is not only equipped with living facilities, but also in order to facilitate people's activities. When the vehicle is stopped, the roof can be raised to facilitate people's walking in the car.
In addition, Stella Vita has digital and transparent control over energy utilization. The team members said that, for example, if you want to make pancakes, it will tell you how much energy is needed to make pancakes.
Thought of Stella Vita
The Stella series of solar-powered electric vehicles are not just designed to earn gimmicks, their commercialization is also advancing. In 2016, 5 alumni of the solar energy team Eindhoven founded Lightyear, a company that commercially produces solar cars for home use. Tijn Ter Horst said: "I think the entire mobile industry can adopt and use many things. When we get home, we will work hard to continue our mission."
Kjell Revenberg, the team manager of the Eindhoven solar team, said: “They are the future, the next generation, and can encourage and accelerate the transition to a more sustainable future. In order to accelerate this transition, we will inspire everything in our journey. It is possible that more Europeans will achieve a sustainable future."
For a project that is ready for commercialization, what we need to study is not limited to innovation. The practicality and reproducibility of the project are also very important.
Stella Vita has broken through its educational background. During the design process, the Stella Vita creative team gained experience from Renault and Mobilize's concept cars-the difference between the concept car and the real vehicle that will be sold later should be as small as possible . And learned some of the design challenges of sustainable mobile vehicles from the two concept cars of Mobilize.
Speaking of challenges, we can focus our perspective on the roof of the car. In fact, the in-car living area, smart cockpit and electrification of Stella Vita are not innovative points. These are all car functions that are already in use. The biggest innovation of Stella Vita lies in its concept-solar mobile homes.
In the traditional electric vehicle system, the vehicle is the terminal, and there are also supporting links such as charging piles and power grids. The density of charging piles and the charging efficiency determine the mileage anxiety of electric vehicle owners. If pure solar power is used and weather factors are not taken into consideration, is it feasible on sunny days?
According to the introduction, the 17.5 square meter solar panel mounted on the Stella Vita has approximately two kilowatts of power, which can generate more than ten kilowatts of electricity per day. It takes 2 to 3 days to fully charge the battery with the solar panel. Therefore, although Stella Vita is advertised as a pure solar-powered car, it is also equipped with a charging port required by a traditional car for car charging, but this function will not be used in this test.
Therefore, the first problem arises, and that is the energy conversion efficiency of solar panels. At present, the theoretical maximum efficiency of single-junction solar cells using only silicon is 33%. In the industry, the photoelectric conversion efficiency of monocrystalline silicon solar cells is about 15%, with the highest being 24%. According to media reports, tested by the German Hamelin Institute for Solar Energy (ISFH), a recognized authoritative testing organization in the world, the conversion efficiency of LONGi's commercial-size HJT (M6 silicon-based heterojunction) solar cells reached 25.82%, breaking the world record. The photoelectric conversion efficiency of polycrystalline silicon solar cells is even worse, about 12%.
For the improvement of the conversion efficiency of solar cells, the industry’s focus is on material research and development. For example, last year, the National Renewable Energy Laboratory used a III-V six-junction structure to achieve a record 47.1% conversion efficiency of solar cells under concentrated light. , The relevant research results were published in the journal "Nature Energy". However, we all know that theoretical research and industrialization still have a long way to go. At present, a conversion efficiency of more than 10% is the norm, and high-end products can reach more than 20%, but 25.82% is already a world record.
The second important point is cost and longevity. Let’s look at the cost first. Statistics show that from 2009 to 2020, the cost of solar panels has been reduced by several times. Take 240W solar panels as an example. The price in 2009 will be 3,000 yuan, and in 2020, it will be 500 yuan. about. When it comes to longevity, we need to look at it from two levels. One is the product's ability to cope with extreme weather, such as hail, and the second is the regular use time. The author sees from the performance introduction of a domestic 240W solar panel that the product can withstand the impact of a solid steel ball falling from a height of one meter. If you ignore this natural disaster factor, more than 95% of the solar panels on the market are laminated and encapsulated with tempered glass, with a lifespan of 25 years, which exceeds the service life of automobiles.
Industry status
In addition to the two concept cars from Mobilize mentioned above, what is the current progress of the overall automotive industry in solar vehicles? Let's take a look at the news from several car manufacturers.
In 2017, the German Sono company released a solar car called "Sion". The car is priced at 16,000 Euros. In addition to the car purchase cost, the user will have to pay an additional monthly rental fee for the battery pack in the future. This car is equipped with A set of 35kWh battery pack has a cruising range of up to 250km, and the solar system can supplement 30 km of cruising every day. Although Sion has not yet mass-produced and plans to start delivering this pure electric vehicle in the first half of 2023, Sono said they have received more than 14,000 orders that paid for the reservation. Currently, Sono is seeking to go public with a valuation of approximately US$1 billion.
More advanced than the Eindhoven solar team and Sono is Aptera, which launched a new energy three-wheeled car without charging at the end of last year. The car is equipped with a solar energy area of more than 3 square meters and 180 solar batteries, without the need to use a charging pile to charge. According to the relevant person in charge of Aptera, it was revealed to the media that the model was sold out less than 24 hours after the start of the sale.
After reading international manufacturers, take a look at the domestic situation. Hanergy released the Solar series of four all-solar powered electric vehicles in 2016. At that time, Hanergy stated that these vehicles already have the basis for commercialization. However, the current few years have passed, and the company has not yet delivered the relevant models in mass production.
Hanergy Solar O (Source: Hanergy official website)
Of course, there are also more conservative explorations, such as the solar sunroof that BMW and Audi studied more than ten years ago, but due to the size, aesthetics and product life, the solution has not been mass-produced. Now Great Wall Motor's Aurora Optoelectronics has restarted this research, using perovskite solar cells with an energy conversion rate of up to 33%, which is expected to be carried on mass-produced vehicles in the future.
