Using Windows to Generate Electricity
A new electricity-generating coating is capable of generating electricity on glass.
Over the years, glass building components such as windows have evolved from simply providing a transparent barrier against the outside environment to fundamentally altering design aesthetics and facilitating energy conservation through the reduction of energy and operating costs. Glass may be a ubiquitous material in the construction of most homes, offices and skyscrapers, but new innovations have the potential to transform these everyday building surfaces into electricity generators to offset buildings’ energy demands.
Heavy demand for energy has motivated the research and development and industrial sectors to develop innovative, more environmentally friendly techniques to generate electrical energy. Recognizing the proliferation of glass as a construction material and its ability to be used in conjunction with specific, performance-enhancing coatings and films, scientists have developed a see-through coating solution capable of generating electricity on glass.*
How It Works
Current conventional solar photovoltaic (PV) modules are made of silicon wafers or thin film that typically require expensive high-vacuum and high-temperature manufacturing processes. These conventional PV modules are many times thicker than the electricity-generating coating and are typically not see-through.
The new coating is a first-of-its-kind, spray-on technology that can generate electricity on glass or plastic while remaining transparent (see Figure 1). The electricity-generating coating is solution-processable at ambient temperature and pressure, helping to lower manufacturing costs. It makes use of the energy of both natural sunlight and artificial light sources, such as fluorescent and LED lighting typically installed in offices and commercial buildings.
The coating is designed not only for functionality but, with an appearance similar to today’s standard tinted windows, will also be aesthetically pleasing or neutral. Carefully developed application techniques, specialty polymers and device architecture all work together to provide an architecturally neutral color and transparent appearance when applied on glass and plastic.
The coating is an organic photovoltaic (OPV) solar array composed of ultra-thin layers forming small cells, using mostly hydrogen-carbon based substances.
When interconnected in a grid-like arrangement, an array of these OPV cells increases the voltage potential and electrical current in a given area.
OPV are third-generation solar cells that typically provide lower efficiencies than conventional silicon and thin-film PV modules. Modifications to the electricity-generating coating are being made to increase power efficiency and become a competitive power offset when compared to conventional solar PV by using large building facades and window surface areas. Green building and sustainable building techniques are looking for more functionality out of building envelope components; this additional functionality needs to be complementary to an existing building’s systems.
The technology is being developed to interconnect into the power system of a building just like conventional PV technologies using the same type of current inversion equipment (i.e., DC to AC) and balance-of-system components that are currently available on the market. The coating is initially targeted for structural and architectural glass for both retrofit and new construction installations.
Today’s OPV market is estimated at $4.6 million and forecasted to rise to $630 million in 2022. The opportunities to install see-through, electricity-generating glass windows in commercial buildings, tall towers and skyscrapers, are significant. According to the Energy Information Administration, the U.S. has nearly five million commercial buildings.
Many factors are driving the green building market, including rising energy costs, increasing electricity consumption, an unprecedented level of government initiatives, heightened awareness and demand for green construction for sustainability and energy efficiency, and improvements in sustainable materials.
According to Pike Research, building-integrated and building-applied PV are set to achieve a compound annual growth rate of at least 41% through 2016. In addition, commercial office buildings and skyscrapers typically lack the rooftop space required for the installation of conventional solar PV modules. This space limitation implies the amount of electrical power that can be generated from a small-area, conventional solar PV array will be inherently low. The electricity-generating provides an opportunity to use a low-emissivity (low-e), ultraviolet (UV)-protecting glass window and transforms this energy-efficient window into an
electrical power-producing window. The high surface area occupied by windows provides an opportunity for the system to offset building energy demand and lower overall energy bills for these commercial buildings and skyscrapers.
The solar power market is intensely competitive and rapidly evolving. Currently, a number of major multi-national corporations produce solar power and develop alternative energy products, including BELECTRIC Solarkraftwerke GmbH, Heliatek, Dysol, Solarmer Energy, BP Solar, Kyocera, Sharp, GE, Mitsubishi, Solar World AG and Sanyo, among others. Future competition will include new entrants to the solar power market offering new technological solutions.
The see-through electricity-generating coating produces electrical energy from natural and artificial light; is developed to be applied to entire facades of skyscrapers; may be an architecturally neutral color; and can be applied to surfaces using inexpensive methods without high-temperature or pressure. These factors make it a technology that warrants attention as it continues to develop.
Glass will continue to evolve in its functionality for buildings. The possibilities for adding power generation to this already popular and necessary building component are worth noting. The new electricity-generating coating and other technologies may allow designers to extend the definition and functionality of the building envelope, which is constantly changing as a system that can provide increasing value to buildings’ occupants and owners.
For additional information, visit www.newenergytechnologiesinc.com.
To learn more about generating electricity with glass, listen to our podcast with Patrick Thompson.