Current research by Stanford University scientists is showing promising implications for the efficiency of solar cells. These solar cells rely on heat loss from radiative cooling and electricity from sunlight. Solar cells utilize photons, light particles, to generate electricity.
In the process, solar cells also generate heat which reduces efficiency. The current research allows the solar cell to draw from a natural thermodynamic resource: the universe. The researchers’ strategy relies on a transparent thermal blackbody, or an object that gives off thermal radiation, which is based on a silica photonic crystal.
The blackbody preserves sunlight while radiative cooling allows a temperature reduction by 13°C of the underlying silicon absorber. Being that the silica photonic crystal enhances sunlight absorption in the absorber structure, it allows for a much larger temperature reduction compared to an absorber structure with a planar silica layer.
The scientists realized that the thermal emission properties of the layers atop the silicon absorber layer in the encapsulated solar cells are far more deserving of attention than past modification suggestions. The blackbody is composed of silica photonic crystal constructed with holes 10 micrometers in depth that are tapered and behave like funnels.
The crystal enables the solar cell to work properly and give off excess heat into the universe. The radiative cooling is predicted to prevent degradation and aid the solar cell in lasting longer.
This means that the cost of solar power will decrease. Although the cooling layer should only be able to help solar cells change about 1 percent more sunlight into electricity, it is a significant improvement relative to past successes. It is also important to recognize the fact that the efficiency of solar cells is not even close to 100%, and that improvement in that regard can only mean that more electricity will be generated.
