Technologies for harnessing energy from the sun have been heavily researched, developed, and commercialized in the past decades as a means to produce clean, sustainable energy and slow down climate change. Photovoltaic cells that sit on the rooftop are now one of the most common commercialized renewable energy technologies in the market and thanks to bright minds like Elon Musk, the boundaries for solar power and power storage are being pushed. Solar panels however, need a large land footprint to generate enough energy to power a small city. This leads us to a future that will be taking advantage of vertical space to reduce the footprint.
Can Windows Power a City?
SolarWindow, a Maryland based company, has been working with the National Renewable Energy Laboratory (NREL) on developing a new transparent solar technology, named solar windows. These windows are comprised of a slightly tinted glass that is able to act as solar panels harvesting energy from sunlight passing through it. The company estimates that their solar window technology can generate 50 times more energy than traditional solar panels when installed on a 50 story building.
How Does It Work?
SolarWindow technology works by applying a thin transparent layer of an organic coating, comprised of hydrogen, carbon, nitrogen, and oxygen onto a piece of glass or flexible plastic. The liquid, also known as Organic Photovoltaic array (OPV), creates a small group of tiny solar cells, or arrays, that generate electricity through the photovoltaic effect when light passes through. The electricity is then harvested using ultra thin wires on the glass that are barely visible to the naked eye. The electricity is then transported to an interconnection point and then into the building’s power system. Although this technology might not generate enough electricity on your living room window, its application can be beneficial when used at a large scale, which is exactly what the company is doing as it targets skyscrapers.
The Difference Between Solar Windows and Conventional Solar Panels
The key factor that allows the the solar window to surpass conventional solar panels is its ability to take advantage of the acres of glass that are often used on skyscrapers while producing energy from natural, shaded, as well as artificial light. Solar panels on the other hand can only use the small space on the rooftop which is not enough to power the high demand of a building. Moreover, by utilizing vertical space we are able to save the acres of land that would have been used to further generate electricity power.
Moreover, the transparency of the solar windows adds two great benefits. The first is that it preserves the aesthetic of the architecture in a building. “Conventional solar panels are inherently opaque and thus impossible to see through,” said the John Conklin, CEO of Solar Window. “You’re not going to build windows from those panels. SolarWindow is being developed to maintain the architectural beauty and transparency of a window while generating electricity.” The second advantage of a solar window is its ability to be integrated into existing window structures in the building without destroying them. “We hope to be able to retrofit existing glass structures as we work on new construction projects” he said.
Furthermore, the production of clean energy technology such as solar panels can often be energy intensive and therefore costly due the high temperature and high vacuum processes required during the fabrication. However, this is not the case for the solar window technology as it depends on an organic liquid coating that can easily be applied to glass at ambient pressure and temperature allowing it to have a low production cost while still being suitable for high speed manufacturing.
Thermochromic Windows
A great emphasis has been placed on solar windows as they provide a great alternative to clean energy while utilizing the existing infrastructure. Scientists at NREL have also been working a solar window technology that uses enhanced thermochromic technology, the same technology used in self-tinting eyeglasses. The glass transition from allowing 68 percent of the light to pass to only 3 percent due to the methylamine leaving the glass when exposed to light. The molecules are reversibly adsorbed once its dark, generating electricity in the process with a peak efficiency of 11.3 percent. Much of the research is being conducted to preserve its efficiency while conserving the transparency of the material. A scientist from NREL stated, “There is a fundamental tradeoff between a good window and a good solar cell,” “This technology bypasses that. We have a good solar cell when there’s lots of sunshine and we have a good window when there’s not.”
The Future of Solar
With the recent breakthroughs in solar window technology you can be sure that future homes, cars, and even phones, will be using glass to generate part of their energy demand. Scientists estimate that solar windows can meet 80% of the electricity demand in the US. This technology can especially be beneficial for countries like China, where pollution has reached phenomenal levels and a large number of skyscrapers exist. Utilizing vertical space and existing structures could potentially provide us with clean renewable energy with the lowest carbon emissions and land footprint.