From electric bikes and scooters to hybrid and electric cars, transportation is undergoing a major overhaul. As the demand for more efficient options rises, the automotive industry is continually seeking new ways to evolve their energy efficient offerings. Though solar power is commonly associated with energy savings on homes and buildings, the integration of solar cells into vehicles is becoming a viable option as tandem technology evolves. Tandem technology would enable solar power to be integrated into the roof or other parts of a vehicle to preserve primary battery power used by car electronics or air conditioning. As an additional benefit, a highly efficient solar roof would extend the electric range of a vehicle substantially.
The main barrier so far in integrating solar into cars is the limited surface area available on the car to accommodate solar panels. To address this issue, efficiency of the solar panel must be maximized—an issue that tandem technology addresses. Tandem cells are solar cells made by stacking two or more cells on top of each other to reach a higher power conversion efficiency (PCE) than what’s possible using separate technologies. Since solar cells with wider-band gap photo absorbers generate higher voltages, thermalization losses are significantly reduced in tandem solar cells, compared with single junction solar cells that absorb the same number of photons. This results in a higher PCE for tandem solar cells.
An obvious requirement is that the material of the top cell is transparent to the light that