Engineers at the University of Michigan and other institutions have created a new solar panel that is transparent enough to be used for windows in homes and businesses. In addition to being transparent, the new solar panels are also highly efficient and have estimated lifespans of 30 years. The team believes their new solar panel could be used to create commercial buildings with surfaces made entirely of solar panels.
If a multistory glass façade building was created using transparent solar panels, the entire building would become a power generator. A lifespan estimated to be three decades is a long time, but commercial buildings will be around much longer than that leading to the question of what exactly happens to the building when the end of that lifespan is reached. Engineers created window-friendly panels after exploring carbon-based materials rather than silicon.
Currently, the most efficient solar panels are made from silicon, but the material isn’t transparent. Two types of materials are used in solar cells known as “non-fullerene acceptors” and “fullerene acceptors.” The former is more robust but less efficient than the latter.
A typical solar cell created using non-fullerene acceptors can achieve an efficiency of 18 percent, near that of a silicon cell. However, they don’t last as long. In experiments, researchers on the project showed that without using methods to protect the material in the panel that converts sunlight to electricity, efficiency declined to less than 40 percent of the initial value within 12 weeks when exposed to the sun.
Engineers studied the degradation in the unprotected solar cell and discovered where they could improve the design. The improvements included blocking UV light by adding a zinc oxide layer to the sun-facing side of the glass. They also integrated a thinner zinc oxide layer adjacent to the region of the cell that absorbs light but also had to add a layer of material called IC-SAM made from carbon to prevent the zinc oxide from breaking down the light absorber. Finally, another layer was added consisting of a fullerene shaped like a soccer ball to protect the light absorber.
Currently, the transparency of the module is 40 percent, but the team believes they can improve that to 60 percent transparency in the future. Their material and also be prepared as a liquid, and the team expects manufacturing costs to be low. Engineers determined their transparent solar panels would maintain 80% efficiency after 30 years.