Two Advances For Glass That Every Window Cleaner Should Know About

3M drew press and viewer interest earlier this week at CEATEC with its show of special film that the company has developed to coat ordinary, existing windows and convert them into solar panels. The product was shown on curved and regular glass surfaces. This “windows-transformative” film is to debut next year. Not only does the panel generate energy in sunlight, but it also serves as a heat-blocking layer.

The film is made from an organic photovoltaic material and fits on windows easily to generate power and cut heat. What is interesting about 3M's technology is its versatility. Claims are that it can generate power, behave as a coolant (absorbing over 90 percent of infrared light) and also protect windows from shattering. The film's narrow, translucent green strips have gaps between them and are glued to windows in large patches. Unlike solar paneling, the films are easy to install. An average person can install the films with no outside assistance, according to a 3M senior manager, Yasuhiro Aoyagi.

While the 3M film for windows appears to be an easy answer to complex and costly solar panel alternatives, the 3M product is not as effective as solar paneling. The film generates only 20 percent of the energy of a regular panel. A factoid frequently included in the CEATEC reports from Tokyo about the 3M product has been that a square meter of the film can generate roughly enough electricity to charge an iPhone under peak sunlight. No pricing details were available but expectations are that the film will be half to two-thirds the cost of solar panels. When the film for windows does hit the Japan market next year, the 3M target user base will be government structures, commercial buildings, and fast-food restaurants.

3M is no stranger to state-of-the-art development efforts in film. The company snagged the world's first patent for window films in 1966. 3M has recognized expertise in both adhesives and multi-layer optical films. Earlier this year, 3M was awarded $4.4 million from the U.S. Department of Energy (DOE). The award, according to the company press release, was made under an initiative to reduce the total costs of photovoltaic solar energy systems by about 75 percent, so that they are cost-competitive with other forms of energy without subsidies.

Samsung breakthrough could turn your window pane into a big ol' LED: Samsung's quest for transparency won't end with laptops, apparently. Today, the Samsung Advanced Institute of Technology announced that its engineers have successfully created "single crystalline Gallium Nitride on amorphous glass substrates" -- an achievement that would allow the manufacturer to produce jumbo-sized LEDs from normal glass, including window panes. Samsung says this scaled-up approach will allow them to lower production costs relative to most LED manufacturers, which rely on sapphire, rather than glass substrates. And, whereas most Gallium Nitride (GaN) LEDs on the market measure just two inches in size, Sammy's technique could result in displays about 400 times larger. "In ten years, window panes will double as lighting and display screens, giving personality to buildings," a Samsung spokesperson told the Korea Herald. Unfortunately, however, it will likely be another ten years before the technology is ready to hit the market. Until then, we'll just have to do our late night window coding the old fashioned way.

Transparent Solar Cell Technology - Turning Windows In To Power Plants

Glass-Like Solar Cells Set Stage for Power-Producing Windows: Add this to the growing list of promising innovations in solar energy: photovoltaic cells that capture energy from sunlight but without changing the way sunlight appears to the naked human eye.  The kicker: you can paint these virtually invisible cells on everyday window panes used in everyday homes and everyday buildings..

Coated onto a pane of standard window glass, a potentially revolutionary photovoltaic technology developed by researchers at the Massachusetts Institute of Technology uses organic molecules to capture the energy of infrared light without blocking the flow of light.  The technology may one day turn everyday wind panes into a source of electric power.  More importantly, it may be cheap enough for people to actually use these power-producing windows.

Vladimir Bulović, a professor of electrical engineering at MIT, and Richard Lunt, a postdoctoral researcher in the Research Laboratory of Electronics, explained the mechanics of this transparent solar-cell technology system in the most recent issue of the journal “Applied Physics Letters.”

The key innovation involved involves a specific chemical formulation used to fabricate the solar cells, which works in tandem with partially infrared-reflective coatings to increase the cell’s efficiency and ensure light flows unimpeded through the cell. All told, the efficiency gain in this process is massive compared to previous efforts to fashion transparent (and non-transparent) organic photovoltaic cells.

Bulović and Lunt also believe their transparent solar-cell technology could cut the cost of traditional thin-film solar products significantly. Currently, installation accounts for more than half of the cost of thin-film solar-power systems comes from those installation costs. Most of the remaining costs are associated with glass and structural components used in the panels.

In a new building, or one where windows are being replaced anyway, adding the transparent solar cell material to the glass would be a relatively small incremental cost, since the cost of the glass, frames and installation would all be the same with or without the solar component, the researchers say, although it is too early in the process to be able to estimate actual costs. And with modern double-pane windows, the photovoltaic material could be coated on one of the inner surfaces, where it would be completely protected from weather or window washing. Only wiring connections to the window and a voltage controller would be needed to complete the system in a home.

Richard Lunt, one of the researchers who developed the new transparent solar cell, demonstrates its transparency using a prototype cell.

Turning windows into powerplants:  If a new development from labs at MIT pans out as expected, someday the entire surface area of a building’s windows could be used to generate electricity — without interfering with the ability to see through them. The key technology is a photovoltaic cell based on organic molecules, which harnesses the energy of infrared light while allowing visible light to pass through. Coated onto a pane of standard window glass, it could provide power for lights and other devices, and would lower installation costs by taking advantage of existing window structures.

These days, anywhere from half to two-thirds of the cost of a traditional, thin-film solar-power system comes from those installation costs, and up to half of the cost of the panels themselves is for the glass and structural parts, said Vladimir Bulović, professor of electrical engineering in the Department of Electrical Engineering and Computer Science. But the transparent photovoltaic system he developed with Richard Lunt, a postdoctoral researcher in the Research Laboratory of Electronics, could eliminate many of those associated costs, they say.

Previous attempts to create transparent solar cells have either had extremely low efficiency (less than 1 percent of incoming solar radiation is converted to electricity), or have blocked too much light to be practical for use in windows. But the MIT researchers were able to find a specific chemical formulation for their cells that, when combined with partially infrared-reflective coatings, gives both high visible-light transparency and much better efficiency than earlier versions — comparable to that of non-transparent organic photovoltaic cells.

In a new building, or one where windows are being replaced anyway, adding the transparent solar cell material to the glass would be a relatively small incremental cost, since the cost of the glass, frames and installation would all be the same with or without the solar component, the researchers say, although it is too early in the process to be able to estimate actual costs. And with modern double-pane windows, the photovoltaic material could be coated on one of the inner surfaces, where it would be completely protected from weather or window washing. Only wiring connections to the window and a voltage controller would be needed to complete the system in a home.

In addition, much of the cost of existing solar panels comes from the glass substrate that the cells are placed on, and from the handling of that glass in the factory. Again, much of that cost would not apply if the process were made part of an existing window-manufacturing operation. Overall, Bulović says, “a large fraction of the cost could be eliminated” compared to today’s solar installations. This will not be the ultimate solution to all the nation’s energy needs, Bulović says, but rather it is part of “a family of solutions” for producing power without greenhouse-gas emissions. “It’s attractive, because it can be added to things already being deployed,” rather than requiring land and infrastructure for a whole new system.

Fine-tuning the cells: The work is still at a very early stage, Bulović cautions. So far, they have achieved an efficiency of 1.7 percent in the prototype solar cells, but they expect that with further development they should be able to reach 12 percent, making it comparable to existing commercial solar panels. “It will be a challenge to get there,” Lunt says, “but it’s a question of excitonic engineering,” requiring optimization of the composition and configuration of the photovoltaic materials.

The researchers expect that after further development in the lab followed by work on manufacturability, the technology could become a practical commercial product within a decade. In addition to being suitable for coating directly on glass in the manufacture of new windows, the material might also be coated onto flexible material that could then be rolled onto existing windows, Lunt says.

Using the window surfaces of existing buildings could provide much more surface area for solar power than traditional solar panels, Bulović says. In mornings and evenings, with the sun low in the sky, the sides of big-city buildings are brightly illuminated, he says, and that vertical “footprint” of potential light-harvesting area could produce a significant amount of power.

A prototype of the MIT researchers' transparent solar cell is seen on top of a promotional item for MIT's 150th anniversary celebrations.

 

 

Max Shtein, associate professor of materials science and engineering at the University of Michigan, says, “This work demonstrates a useful effect, and is based on very sound science and engineering.” But he adds that “it is but one of the many other methods by which a similar functionality could be achieved,” and says the biggest uncertainty at this point is that because they are so new, “the lifetime of organic PV cells is a bit of an unknown at this point, though there is some hope.” In addition, Shtein says, “The potential of this technology is good if projected far into the future,” but only if the efficiency can be improved as the researchers expect it can.

As added benefits, the manufacturing process for the MIT researchers' solar cells could be more environmentally friendly, because it does not require the energy-intensive processes used to create silicon solar cells. The MIT process of fabricating solar cells keeps the glass panes at ordinary room temperature, Bulović noted. Installations of the new system would also block much of the heating effect of sunlight streaming through the windows, potentially cutting down on air conditioning needs within a building. The research was funded by the Center for Excitonics, an Energy Frontier Research Center funded by the U.S. Department of Energy.

Windows Of The Future

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Rainbow Solar Inc. (RSi) recently announced the world’s first, transparent, photovoltaic-glass window that generates 80 to 250 watts of electrical power, while saving up to 50% on heating and cooling requirements too.
This is the first production BIPV (building integrated photovoltaic) product of its kind, an enclosed super tempered glass window system, with a patent pending, fully integrated, multi-tier photovoltaic and heat insulation technology. Current production lines are capable of producing window sizes up to 9’ x 9’ (2.74m x 2.74m) with comprehensive options, such as fire and bullet proofing, to meet design, weather, climate, and building code requirements.
The RSi PV-Glass Window uses sunlight to generate electricity, reduce heat, and provide a semi-transparent window that allows for privacy, while maintaining a comfortable level of visibility to the outside world. At the same time, RSi PV-Glass Windows provide a 100% reduction in Ultraviolet and Infrared radiation, adding an extra level of protection not offered by standard glass windows.
RSi embedded many smart home technologies into the complete window system, including an optional built-in electrical privacy curtain, to completely block out an already shaded glass window, and a new technology that converts the entire window into a light panel.
RSi’s vision is of buildings that harvest their own energy from unlimited renewable sources. What the company ultimately proposes to do is to eliminate the need for electrical power plants, as well as the grid infrastructure so that the building itself becomes truly autonomous and fully sustainable in terms of electrical power.
Since one of the biggest heat losses from a home is through a glass window, it looks like RSi has a winning combination, stopping heat loss on cold days and keeping heat out on hot days, while generating electricity at the same time. Let’s hope the opaque windows also stop birds flying into windows and then the only remaining technical challenge is implementing self-cleaning windows.