Optical challenges for terawatt-scale photovoltaics

We present a critical review on optical research in photovoltaics guided by the question: Which topics do we regard as most relevant to accelerate the large-scale implementation of photovoltaics? The following areas were identified: 1) The development of high-performance earth-abundant solar cell materials and the reduction of indium and silver in the device. 2) Color concepts for an appealing optical appearance of solar modules as photovoltaic modules enter urban environments as well as agricultural areas on a large scale. 3) Optical optimization of multijunction solar cells based on perovskite, III-V semiconductors and silicon to overcome the single-junction efficiency limit. 4) Accurate energy yield predictions considering the full complex illumination conditions particularly regarding bifacial and multijunction solar cells. 5) Advanced concepts with strong momentum such as radiative cooling and spectral conversion.