The concept of solar skylights is not new. In the 1980s, the audi 80 Coupe sports car was equipped with a solar roof, but due to the technical difficulty and price, this product was only a luxury car for a long time. Now, with the rapid development of panoramic skylight and the trend of energy saving and environmental protection, this product has once again attracted the attention of various automobile enterprises, and began to be gradually applied in ordinary models by "wang xie tang qianyan", such as Toyota prius PHV, Volkswagen phaeton, haorui, etc. For the popular trend of the future panoramic sunroof, this article will from the application present situation, the types of technology and development trends of 360 ° panoramic dialysis, reference for car powder!

Definition: what is a solar sunroof?

Simply put, a solar sunroof is a solar panel integrated under a common sunroof, which converts ultraviolet and infrared radiation from the sun, which is harmful to human health, into electricity. And what really makes it different is that the solar sunroof is your car has two functions: one is ventilation. Especially in the hot sun parking period through the solar sunroof sustainable ventilation system for the car to provide electricity, the introduction of fresh air to drive out the car heat, in order to achieve the purpose of cooling. Second, the battery can be charged to achieve energy saving and consumption reduction. Especially for new energy vehicles, but also can effectively increase the range.

Because of this, solar skylight has become the best skylight products.

Market application: more than 20 years of "dormant" development

Although solar sunroof has become famous in recent years, it has been dormant for many years.

Solar Windows on top of audi cars

It is understood that as early as more than 20 years ago, the world's first skylight industry "hegemon" wei Baxter has begun to arrange solar cells on its products, mainly to reduce the temperature of the carriage under the scorching sun. In hot summer when the cooling effect can reach more than 20 degrees.

Until last year, Toyota focused on "charging and storing", another feature of the solar sunroof. In its latest hybrid version of the prius, it began using the roof's solar cells to charge the car's battery pack.

Usually, an actor needs to have a solid foundation in order to be popular in movies and TV series. At the same time, he needs to look at the right place at the right time and good luck. This is also true for a product. After more than 20 years of tempering, the solar sunroof technology has been gradually mature, in addition to Toyota, audi, Mercedes, Cadillac, Volkswagen and other parts of the model is also equipped with, and now in the environment of energy saving and emission reduction and consumer upgrade of the market, the growth momentum of this product is germinating.

Technical architecture: multiple solar cell technologies coexist and derive

The gradual improvement in the market for solar skylights has led to a number of competing investments by product and technology suppliers, with different solutions and technology paths. Outpost jiang, executive vice President of sandi solar, introduced to me that two technologies currently used in the solar industry, crystalline silicon solar cell technology and thin film solar cell technology, have applications in the automotive industry.

Technical features can be summarized as follows:

Crystalline silicon solar technology is the most mature and cheapest solar power generation technology at present. It has been widely used in outdoor photovoltaic power stations and residential rooftop distributed photovoltaic systems, and the current battery cost is less than 1.7 yuan/watt.

Outdoor photovoltaic power station residential roof distributed photovoltaic system

"Monocrystalline silicon cells cost a little more, but have a uniform surface color, which makes them ideal for cars with limited area and demanding appearance." "Concluded outpost jiang, who had worked in foreign multinationals before returning to China to work for private companies for many years.

Sandy light energy company's director of research and development, introduce the author Dr Wang Minghua ford 2015 Cmax plug-in hybrid concept car, USES the IBC (fork electrode back contact) structure [1] monocrystalline cells, the photoelectric conversion efficiency is as high as 23%, but you need to form a complete set of concentrated ceiling and the roof of the battery to work together to achieve the ideal charging efficiency, use rise slightly inconvenient. Toyota's 2017 plug-in hybrid prius has a HIT (heterojunction) monocrystalline silicon battery, and its battery efficiency is as high as 22%. In addition to the above two types of cells, major domestic solar manufacturers are currently promoting the mass production of single-crystal silicon cells with PERC (back passivation) structure [3]. The mass production efficiency of PERC cells has now exceeded 21%, and the cost per watt is close to that of polycrystalline silicon cells.

Although crystalline silicon solar cells have been used for a long time and are relatively mature, they still have some "barriers" that are difficult to cross. "Because solar wafers are only 0.2mm thick and brittle, they require a special pressing process on the curved surface of the roof to ensure a high yield," said Mr. Jiang.

The solar roof of the Toyota prius PHEV

Ford's cmax plug-in solar roof

Thin-film solar cells are a late starter in the automotive field compared to crystalline silicon solar cells, but they have an advantage that the latter does not: they use flexible substrates and can be bent. It is known that the light-proof solar roof developed by hanergy company adopts CIGS (copper indium gallium selenium) thin-film solar technology [4]. The photoelectric conversion efficiency reaches more than 13% of the module efficiency. However, the defect of CIGS film is that it is made of stainless steel substrate, which is not transparent. Compared with crystalline silicon cells, they are less efficient, more expensive and less attractive. In addition, the application of CIGS solar cells to cars also needs to solve the problem of environmental protection and recyclable materials. Because the window layer in CIGS USES CdS (cadmium sulfide) film, cadmium element is one of the elements strictly controlled by ELV regulation in the automotive field and ROSH regulation in the consumer electronics field, whose content is required to be less than 100ppm. Therefore, to solve the problem of raw material pollution, a more environmentally friendly window layer material must be developed to replace cadmium sulfide. However, at present, none of the new materials can achieve the high battery conversion efficiency as CdS.

Hanergy displays the CIGS thin film solar roof

There is another thin-film technology in the industry -- silicon-based thin-film solar cells [5]. Dr Yang Liyou is the earliest Chinese scientists engaged in this type of battery, the department of energy (doe), a former adviser, more solar cells research organizations in the United States lead the r&d team research more than 20 years, and created the world record for the thin film solar cell conversion efficiency, now served as director of international semiconductor association (China) and pv (the) chairman of the committee, national one thousand plan. Led by Dr Yang Liyou sandy light energy research and development team, for the first application of thin film solar cells in the world to the bending of automobile skylight glass or glass roof, while keeping the panoramic roof light is bright and beautiful at the same time can power generation, and the material is environmental protection material, can meet the requirements of vehicle parts recycling. It is understood that this technology was quickly by the wei basset, yutian crown good, ying na fa and other domestic and foreign skylight suppliers and Europe and the United States, South Korea and domestic independent brand vehicle manufacturers welcome.

Transparent membrane solar sunroof assembly

In addition, according to experts, in the whole field of flexible thin-film batteries, the highest efficiency is the gallium arsenide battery [6] purchased by hanergy of the United States [6], and the theoretical photoelectric conversion efficiency can reach 30%. It is estimated that under sunny weather, it can support the car to travel 30~60 kilometers. During driving and parking, flexible thin-film battery components can be realized to charge the power battery pack, thus getting rid of dependence on fixed charging facilities and achieving zero consumption of fossil energy and zero emission of pollutants. But gallium arsenide is still expensive to make, costing about 50 times more than current crystalline silicon, and the thin-film cells, while flexible, are opaque and do not maintain the light and aesthetics of panoramic skylights. Similar to gallium arsenide, perovskite and organic dye-based solar technologies are either toys for scientists' LABS or ephors with a lifespan of just a few hours, leaving the automotive industry with a wide range of high-quality, low-cost standards.

Hanergy gallium arsenide solar cell concept car

Development prospect: the critical point of market demand has been reached

"Regardless of the above technologies, the application of solar cells in automobile is highly anticipated and the market demand is over." Dr. Yang liyou said, "first of all, the trend of energy saving and emission reduction, especially with the development of new energy vehicles, solar sunroof energy saving properties and advantages will be more prominent, not to mention the economic value, from the point of view of environmental value, I firmly believe that for people engaged in this industry all efforts are worth watching. According to the specifications and requirements of the automobile industry, our team tailor-made solar cells for automobile manufacturers.

With the upgrading of consumption level and younger consumers, the demand for cars has changed from the original pursuit of comfort and safety to focus on functionality and personalization. The solar energy technology itself can bring a series of highly technical and cool products such as intelligent car roof, color-changing sky curtain and dimming sunroof, which can meet the personalized needs of consumers.

However, although the market demand has arrived, solar sunroof still faces many years of promotion "hidden pain" - price. For this problem, Dr Yang in "science" way to reporters calculated brushstroke zhang: a 100 w solar roof, one year accumulative total theory capacity can reach 130 ~ 175 degrees, all put into the battery pack, for electric cars a year increased range can reach 650 ~ 900 km, if a user's typical driving habits are 15000 kilometers, equivalent to range increased by 4 ~ 6%. If it is a hybrid or a traditional oil-burning car, all the electric energy saved can reduce the fuel consumption used by the engine to generate electricity. According to the fuel consumption rate of 250g/ KWH, and the motor efficiency is 80%, the solar sunroof of 100W can save as much as 60-80l in a year, and the fuel money saved in a year is nearly 500 yuan.

"Manufacturing costs will come down with volume production, and now it's up to the car companies who are willing to be the first to follow suit," Dr. Yang said.

To sum up, no matter from the economic level or the user experience level, whether it is fuel car, hybrid car or electric car, solar energy technology has a lot of application space. "Driven by China's new energy vehicle industry policy, solar sunroof has great potential in China," said the head of vibast in an interview.