A lot of sunlight energy goes to waste every day just passing through your window. Imagine if, instead, those windows could capture that energy and use it to power your home or business. With transparent solar panels, that dream could become a reality.
Windows Made of Transparent Solar Panels
The relatively new technology to enter the world of solar power is photovoltaic (PV) glass, also known as transparent solar panels. (1) This technology can essentially turn any window into a power-producing unit. This includes the windows on our buildings and homes, car windows and sunroofs, and even smartphones. (1) Researchers at Michigan State University were the first to create this type of clear solar panel in 2014, researchers elsewhere in the United States and Europe have been able to create fully transparent solar glass. (1)
How Do Transparent Solar Panels Work?
The job of a solar panel is to absorb sunlight and convert that sunlight into power. Until now, clear solar panels weren’t possible because the light passes right through the glass instead of being harnessed for energy production. (1) This new technology can essentially turn any glass sheet or window into a PV cell. This cell selectively chooses a portion of the solar spectrum that the human eye can’t see while allowing the rest of the light to pass through. It does this using a transparent luminescent solar concentrator (TLSC). (1)
The TLSC is made of organic salts that absorb specific invisible UV and infrared light wavelengths. These are then made to glow as another invisible wavelength. That wavelength is then transferred to the edge of the window, where thin PV solar strips convert it into energy. (1)
A Powerful Discovery
In August of 2020, Michigan University researchers set a new record for the efficiency of color-neutral transparent solar cells. (2) Using an organic, carbon-based design, they achieved (2):
- 8.1% efficiency
- 43.3% transparency
Previous transparent solar cells have only had a 2 – 3% efficiency, so this is most definitely a breakthrough. (2) To put this into perspective, regular nontransparent solar cells have an efficiency between 15-20% (4). While transparent solar may not stack up when compared to standard solar technology, it’s improving.
Creating Energy and Reducing Brightness
The cells are similar to the grey tint of car windows or sunglasses but instead have a slightly green appearance. “Windows, which are on the face of every building, is an ideal location for organic solar cells because they offer something silicon can’t, which is a combination of very high efficiency and very high visible transparency,” Engineering professor Stephen Forrest explained. (2)
Most building windows already have a coating on them to help reduce brightness and heat inside the building. The idea with the transparent solar panels is to use them to create energy instead. (2)
Not 100% Transparent Yet
UbiQD, an advanced materials company in New Mexico, is currently working on transparent solar panels that look just like regular, clear glass. They are using a technology called quantum dots. These are microscopic nanoparticles that manipulate light. (2) Some of the newer smart TVs use the same technology.
Quantum dots (nanoparticles) are so tiny that it would take 100,000 of them to cover even just your fingernail. They have extremely high efficiency and size-tunable photoluminescence, or light emission, in several colors. (2) Though the efficiency of these panels is only 3.6%, it is promising for the future. (3) UbiQD has already partnered with quantum dot manufacturer Nanosys to create panels for greenhouses that help plants get more from the sun. (3)
Windows to Power The Nation
The United States has an estimated five to seven billion square meters of glass surfaces. This means that transparent solar panels have the potential to meet up to 40% of the country’s energy demands. Combined with rooftop solar panels we have the potential to meet 100% of our current energy needs. (1)
- “Transparent Solar Panels: Reforming Future Energy Supply.” Solar Mag. February 29, 2020.
- “how transparent solar panels + ‘quantum dots’ could harvest energy on an architectural scale.” Design Boom.
- “EGEB: Solar-window tech makes a leap forward with better clarity” Electrek. Michelle Lewis. September 2, 2020.