Zeiss Solar Window: The window as an energy source and invisible - the way it works is completely different than you first suspect

Solar windows rethought: Zeiss presents exciting solar technology with a wow effect

“Zeiss Solar Window: The window as an energy source and invisible – How it works is completely different than you think.” With this in mind, the renowned optics company Zeiss presented a remarkable technology at CES 2025 in Las Vegas that changes our perspective on windows, solar technology and energy efficiency could fundamentally change. This innovation uses a combination of holographic and micro-optical elements to direct sunlight specifically to solar cells in the window frame without significantly changing the appearance and transparency of the pane. At a time when intensive work is being done worldwide on sustainable energy supply solutions, the Zeiss Solar Window could be a pioneering step towards making buildings more efficient, more environmentally friendly and at the same time more aesthetically pleasing. Below we explain how it works in detail, highlighting applications, benefits and potential challenges. In addition, examples are given of how the Zeiss Solar Window can enable a variety of innovations in the area of ​​smart glass beyond pure energy generation.

The underlying technology: holography and micro-optics

The highlight of the Zeiss Solar Window is the use of a special film that is integrated into the glass. This micro-optically structured film redirects parts of the incident sunlight so that light in the infrared and near-infrared range in particular is directed to the solar cells in the window frame. Most of the visible light remains transparent, so that the windows appear as clear as possible to the outside. Holography comes into play by deflecting light in specific directions using targeted interference patterns. While holographic effects are often known for impressive plays of light and color changes, these are almost invisible with the Zeiss Solar Window because a large part of the visible light spectrum is allowed to pass through unchanged.

In “conventional” solar cells, sunlight is captured over as large an area as possible on a silicon or other semiconductor base and converted directly into electrical energy. In contrast, the Zeiss system works with a significantly smaller but highly specialized solar cell. This is built into the frame of the window and - according to Zeiss - achieves up to 20 percent of the efficiency of a classic solar cell. This is remarkable for this type of application because the area of ​​the active solar cells is comparatively small. The trick lies in focusing and concentrating the infrared light on a smaller area, which means that considerable amounts of energy can be obtained despite the smaller active area.

Invisibility and transparency

One of the most important questions with any glass innovation is: “Does this new technology affect visibility or design?” Many previous attempts to use windows as an energy source have often compromised on transparency. Either the window was significantly darkened or it appeared colored in certain lighting conditions. The integration of solar cells also often led to optical impairments, for example due to visible conductor tracks in the glass.

Zeiss, on the other hand, emphasizes that the micro-optical film should be practically invisible and maintain a light transmission of over 95 percent. “We have invested a lot of development work to ensure that the appearance of a conventional window does not change noticeably,” say company sources. From an aesthetic perspective, this is a decisive breakthrough, because it is essential for architects and builders that the appearance of the building does not suffer from technological innovations. If the technology can actually be integrated as seamlessly as Zeiss suggests, it could open up entirely new possibilities for widespread use in buildings - from modern, glazed skyscrapers to smaller residential buildings.

Energy production and temperature regulation

A key advantage of the Zeiss Solar Window is its double sustainable effect: on the one hand, electricity is generated, and on the other hand, the film can regulate the room temperature. Infrared light in particular contributes to heating up interior spaces as it transports heat energy. If some of this infrared radiation is deflected to the solar cells, less heat penetrates into the building. The result is a room climate that has a positive effect, especially in hot regions, and can reduce the need for air conditioning.

With every ray of sunlight captured and converted into electricity, the overall energy efficiency of the building increases. The efficiency Zeiss is aiming for of up to 20 percent of comparable solar cells may not sound breathtaking at first glance, but one should not forget that this is a technology that involves the use of huge glass surfaces that have to be installed anyway Electricity generation can be used. Overall, this can generate significant amounts of energy – especially in bulk – and contribute to the overall building balance.

Possible areas of application in buildings and beyond

In its presentation, Zeiss highlights various areas of application for the solar window. Classic office buildings with large glass facades are ideal because of their extensive window areas. In modern cities, skyscrapers or at least multi-story office complexes with extensive glass fronts are common. With each additional floor, the potential area that can be used to generate green energy increases. In addition, there are residential buildings in which windows - regardless of their size - could now be combined with other solar technologies (e.g. on the roof) to ensure a higher degree of self-sufficiency in the power supply.

Another exciting area is roofing: canopies, patio roofs or even carports. These surfaces are now often designed to be transparent or semi-transparent to allow light to pass through. Why not generate energy at the same time? “Invisible” solar glass is an attractive option, especially where the design requires a certain lightness and the area is primarily intended to protect against precipitation.

Roof windows and skylights are also ideal for use as they offer direct sunlight from usually a steep angle. Winter gardens, on the other hand, could not only be flooded with daylight with this innovation, but could also be designed to be energy-positive at the same time. Although you can achieve good yields with conventional solar cells on inclined or horizontal surfaces, winter gardens often require the clearest possible view. A holographic film that only redirects infrared light could be perfect here.

Technical challenges

As impressive as the technology sounds, the question arises as to its technical feasibility on a large scale. On the one hand, the holographic film must be applied evenly in large-format glass panes. So far, holographic elements have only been known on a smaller scale. A production technology must be established here that guarantees consistent quality with large quantities and large dimensions.

In addition, the solar cells used in window frames are exposed to special challenges: They have to withstand heat, cold, moisture and other environmental influences without their performance suffering excessively. Zeiss is aware of this and refers to years of research in materials science that should enable robust and long-lasting integration of the cells. Nevertheless, it will probably take a while before the technology goes into series production and can be used across the board.

Economic aspects and cost efficiency

Another crucial criterion for the market success of the Zeiss Solar Window is the question of cost-effectiveness. Because even if the idea is fascinating, builders, architects and investors have to see the added value in relation to the costs. According to its own statements, Zeiss plans to make the technology available to other manufacturers as a system supplier. This means that Zeiss would supply the micro-optically structured film, the integrated solar technology and the electronics, while window manufacturers would take over the production of the complete windows. Such a licensing strategy is common in the industry and allows new technologies to become more widespread more quickly.

However, if the costs for a Zeiss Solar Window are significantly higher than for a normal window plus a conventional PV system on the roof, it could be more difficult to convince potential customers. On the other hand, early integration into the facade means that builders may be able to do without classic PV modules or at least require less space for them. In addition, support programs or government incentives for renewable energies can make market entry easier.

Aesthetic innovations and added value for architecture

An interesting topic is how architects and designers could work with the Zeiss Solar Window. If it is actually possible to integrate the technology almost invisibly, it will open up new design possibilities. Glazed building shells have long been standard in modern architecture. With the Zeiss system, not only the exterior walls, but also artistic glass installations indoors or outdoors, glass railings or even special glass floors could be equipped with solar cells without affecting the feeling of space.

In addition, Zeiss promises that the technology can be expanded in the long term. The holographic film could be adapted for different spectral ranges, perhaps allowing architects to create additional effects. It would be conceivable to consider glass surfaces that harvest energy during the day and glow in a subdued light at dusk in order to set certain architectural accents. This could result in completely new aesthetic and lighting concepts.

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Future vision: “Multifunctional Smart Glass”

Zeiss speaks of a “Gutenberg moment” for holography. While today's holograms are often limited to special applications, a multifunctional glass market could emerge in which not only energy generation but also other smart functions are integrated. The company has already shown at CES that invisible cameras or sensors can be housed on the same glass panel. Driver assistance systems in vehicles could be made much more inconspicuous or security cameras in buildings could be made practically invisible.

Another highlight: holographic displays. “We enable augmented reality displays on windshields without taking up additional installation space,” said a statement from Zeiss. This means cars could be equipped with windshields that project driving information directly into the driver's field of vision. This function could also be used for other means of transport or machines, and all without bulky projection devices that currently take up a lot of space.

The idea of ​​intelligent lighting in the interior is also fascinating. Why not use light collected during the day to create a daylight-like ambience in the evening? With the help of special holographic elements, the light can illuminate the room seemingly from nowhere, without any visible lights being installed. Such concepts are still visions, but it is already clear what potential this technology could develop.

Sustainability and ecological perspective

One of the biggest drivers in the development of new solar technologies is the urgent need to replace fossil fuels and reduce global CO₂ emissions. The Zeiss Solar Window could make an important contribution here if it is possible to use glass surfaces for energy on a large scale. Modern cities are characterized by huge window surfaces, which so far only let light into the interior or serve the aesthetics of the building. If these windows also generate electricity, this increases the share of renewable energy in the overall mix.

Another environmental benefit is the reduction in building cooling by redirecting infrared light, which can reduce the energy required for air conditioning. In many regions of the world, cooling buildings is becoming increasingly important, especially in times of climate change and rising global average temperatures. The Zeiss Solar Window could provide noticeable relief here.

Of course, the final ecological balance also depends on the manufacturing process. The production of micro-optics, holography and solar cells consumes resources and energy. However, companies like Zeiss are working to make these processes ever more efficient and sustainable. In the long term, the increased lifespan of glass facades with integrated energy generation could result in the initial manufacturing costs and ecological footprint being amortized.

Integration into smart buildings

Smart buildings are a growing field in architecture and building technology. Sensors, actuators and smart systems are used to automatically control energy requirements, air conditioning, lighting and security. The Zeiss Solar Window fits perfectly into these developments. On the one hand, it supplies energy, and on the other hand, the integrated sensors and cameras could take on additional functions: measuring the angle of incidence of the light, analyzing the heat supply, illuminating the interior or even controlling automated shading when the sunlight becomes too intense.

In combination with building management technology, individual windows could be dynamically optimized. If you think further into the future, you can imagine windows detecting external lighting conditions in real time and only allowing solar energy in when it is needed. At the same time, excess light could be used to charge batteries or operate other systems in a micro-grid, making the building almost self-sufficient.

Possible synergies with other technologies

The Zeiss Solar Window is not alone in the innovative world of renewable energies. More and more start-ups and established companies are working on transparent photovoltaic solutions, organic photovoltaics or other forms of energy-generating glass surfaces. Although the Zeiss system has its own unique approach due to its micro-optical and holographic orientation, synergies with other developments are still conceivable.

For example, window-integrated solar cells could be combined with heat recovery systems. If incident light in winter is converted into heat, this energy could be stored in a targeted manner. A smart building could use sensors to decide when to absorb or release heat. Networking vehicles, buildings and infrastructure with such windows is also conceivable: electric cars could park directly in front of windows that supply electricity wirelessly or via a plug-in.

Invisible cameras and security applications

With its Multifunctional Smart Glass technology, Zeiss also emphasizes the possibility of invisibly integrating cameras and sensors into glass panes. This could be used in many areas: surveillance cameras in public buildings, security solutions in airports or train stations and even driver assistance systems in vehicles. “If you can’t see the cameras, the design is more harmonious and the functionality is expanded,” says Zeiss.

At the same time, invisible cameras raise new questions in the area of ​​data protection and privacy. If a company or an authority installs cameras in window panes in such a way that they cannot be seen, the question arises as to whether there is sufficient labeling and the legal framework. So there are not only technical, but also social and ethical discussions about how far the integration of smart technology into everyday environments should reach.

Holographic displays for augmented reality

A particularly futuristic-looking aspect of the Zeiss Solar Window is the ability to create holographic displays on glass. Imagine looking out the window and, almost like in a science fiction film, information is displayed: weather forecasts, temperature, time, perhaps a layer of augmented reality that projects building outlines or street information into your field of vision.

Not only private households, but also industry and commerce can benefit from this. In production facilities, glass panels could be used to display work instructions or real-time data without the need for additional monitors or tablets. The topic of head-up displays is already well known in the automotive industry, but conventional systems quickly reach the limits of space and integration options. A holographic display in the windshield that doesn't require a visible projector could be very attractive to manufacturers.

Maintenance and longevity

The maintenance and longevity of such an innovation are critical factors for practical use. Conventional glass surfaces can be cleaned regularly without affecting the interior. However, with the Zeiss Solar Window, the intelligent film is integrated into the glass package, so that ideally it is permanently protected from environmental influences. However, temperature changes and UV radiation can leave their mark over the years.

The integrated solar cells in the window frame also require a design that can withstand moisture and strong temperature fluctuations. Here, manufacturers have to ensure that the cells remain functional for many years. Zeiss will likely offer guarantees or certifications to increase confidence in the technology. Ultimately, economic viability depends heavily on how long the system can supply electricity without significant losses in efficiency.

Assembly and retrofitting

In new building projects, integrating the Zeiss Solar Window should be comparatively easy, as the windows can already be taken into account in the planning phase. For existing buildings, however, the question of retrofitting arises. Theoretically, a building that already has large window areas could be equipped with new windows. However, this means a significant amount of conversion effort, which is why the economic viability of retrofitting must be carefully considered.

Nevertheless, there could be attractive pilot projects, for example when renovating large office complexes where the windows have to be replaced anyway. In such cases, the Zeiss Solar Window can be installed directly in place of the old windows, making the building partially energy self-sufficient after renovation and receiving the most modern technology. However, for individual homeowners who only want to replace a few windows, it remains to be checked whether the achievable energy yield justifies the price.

Competition with classic solar modules?

The question that arises is whether the Zeiss Solar Window competes with conventional solar modules or could even replace them. Realistically, it will be more of an addition. Classic photovoltaic modules on roofs still deliver high efficiency at comparatively low costs. Windows, on the other hand, are primarily used for visibility and must meet other requirements. However, the Zeiss Solar Window can open up additional energy sources, especially where roof space is limited or where you already have large glass surfaces.

In addition, in urban areas where the roofs of high-rise buildings quickly reach their capacity limits, it can make a lot of sense to also use the facades. A combination of roof PV system and solar windows leads to maximum utilization of solar energy and could even ensure the energy self-sufficiency of buildings - especially if storage technologies are further expanded.

Potential markets and global perspective

The global markets for building and energy technology are huge. Particularly in regions with high levels of solar radiation, such as parts of Asia, Africa or South America, the demand for window solutions for generating electricity could be very high. At the same time, there is a high need for cooling, which the Zeiss Solar Window can reduce by redirecting the infrared light.

Even in Europe, where sustainability and energy efficiency have strict legal requirements, architects and builders are always looking for innovative solutions to build climate-friendly buildings. The energy efficiency standard is constantly being raised, especially in new buildings, which makes the integration of modern solar technologies practically a must. This means there is great potential for companies like Zeiss to market their system worldwide, provided it actually fulfills the promised properties in terms of transparency, efficiency and aesthetics.

Market launch challenges

Even if the Zeiss Solar Window appears promising, there are of course challenges that need to be overcome. In addition to the aforementioned question of production capacity and costs, the customer benefits must also be communicated precisely. Many potential buyers are initially skeptical about new technologies. You want to see concrete data on efficiency, longevity, maintenance and payback period.

There is also the need to secure the technology from an architectural and regulatory perspective. New types of facade elements are not readily permitted in all countries. Building standards and regulations regarding fire protection, statics and building insulation must be adhered to. The electrical regulations for wiring solar windows should not be underestimated either. Zeiss will therefore have to work closely with standards and approval bodies to bring the technology to market quickly.

Vision: Buildings as power plants of the future

In a world that is increasingly moving away from the central power plant model towards decentralized energy networks, there is great potential in technology that transforms buildings into smaller power plants. Zeiss is taking a step in this direction with its Solar Window. If every window in a high-rise building generates electricity and this electricity is distributed or stored in an intelligent micro-grid, you get closer to the idea of ​​a decentralized energy supply.

At the same time, the burden on the electricity grid is relieved by linking local production and consumption. An office building could partially cover its own electricity needs for lighting, air conditioning or computer systems. Together with other renewable sources such as rooftop solar cells, geothermal energy or wind turbines in urban areas, a mix is ​​created that helps drive the energy transition. The Zeiss Solar Window is an important piece of the puzzle in this context.

Innovation driver Zeiss and cooperation opportunities

Zeiss is a world-famous company that originally made a name for itself primarily through high-quality optical systems. In addition to camera lenses and microscopes, Zeiss has long been covering a wide range of high-tech applications. The development of the Solar Window shows how the company is using its expertise in optics, micro-optics and materials science to open up completely new markets.

From the perspective of the cooperation partners, it makes sense that Zeiss will work closely with leading glass manufacturers, architectural offices, property developers and the energy sector. In this way, pilot projects can be implemented that show the technology in practical use. Research institutes or universities could also be interested in such collaborations in order to investigate the effects on building ecology or the urban energy balance.

Beyond the “Gutenberg moment.”

Zeiss itself uses the term “Gutenberg moment” to illustrate the potential of its holography technology. Johannes Gutenberg revolutionized book printing and ensured the rapid spread of knowledge. Similarly, the availability of a stable, cost-efficient and mass-produced holography for glass should lead to a boost in innovation in a wide range of areas. It will be interesting to see in which industries and applications we will find holographic systems in the future: from solar energy and vehicle technology to entertainment, education and medicine.

The challenge is to sustainably build up this technological lead while meeting market expectations. If Zeiss manages to reduce production costs and prove the reliability of the systems, the solar window could actually become widespread. How long this will take depends on progress in research and development, but also on external factors such as market demand, political conditions and the availability of raw materials.

A window into a sustainable future

“Zeiss Solar Window: The window as an energy source and invisible – the way it works is completely different than you think.” This slogan gets to the heart of the idea: Windows that can do more than just let light through can lead us towards a more sustainable future . The combination of holography, micro-optics and highly specialized solar cells promises a technology that is elegant, efficient and environmentally friendly. At the same time, it opens the door to a world in which glass is not just a passive component, but rather plays an active role in energy generation, climate control and information display.

Time will tell whether the Zeiss Solar Window will catch on in the broader market. There is much to suggest that buildings are increasingly becoming “smart environments” in which integrated sensors and renewable energy technologies play a natural role. If the technology can be manufactured cost-effectively and robustly, the dream of energy-generating facades could be within reach. And not only that: other conceivable applications such as invisible sensors, holographic displays and intelligent lighting also give “Multifunctional Smart Glass” a special appeal.

In a world characterized by growing hunger for energy and the struggle for climate-friendly solutions, any innovation that harmoniously combines aesthetics and function can be a milestone. The Zeiss Solar Window seems to be well on its way to becoming such a milestone. It opens up new perspectives for architecture, design and sustainable energy production. And it gives us hope that one day we will live in cities where even the most inconspicuous window helps us move one step further on our path to a low-carbon society.

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