Advanced Solar Power Technology-Multiple Junction Photovoltaics

Abstract

Solar energy is the primary energy source for human civilization on earth. It is estimated that less than 5% of solar energy arriving earth stays through photosynthesis and earth surface heating which causes wind and weather fluctuations. However, it was reported that even with a 160 km square area solar photovoltaics (PV) installation in Nevada, the generated power would have been sufficient for the entire power need in the USA. Although the world cumulative PV installation has reached 415 GW as of the end of 2017, this is far from being a noticeable power source for our daily activities. Increasing renewable energy shares in our total energy consumptions is crucial to reducing air pollution from fossil fuel power plants. To speed up PV installations, high solar efficiency solar cells must be used, and the installation cost must be lowered. The development of high-efficiency solar cell technology is essential for the satisfactory adoption of solar power in our society. To become the primary power source, solar power industry must also resolve the no power generation situation during evening and rainy days. Low-cost energy storage technology can provide a solution for such conditions. Presently, the most efficient solar PV system is of multiple junction solar cells. The best multiple junction solar cell in the laboratory was reported to be 46% by Fraunhofer. It is expected that a 50% cell be developed in the next few years. We have analyzed the best possible multiple junction design and reached a conclusion that the theoretical efficiency of a multiple junction cell can be as high as more than 70%.