One-year outdoor operation of monolithic perovskite/silicon tandem solar cells

Perovskite/silicon tandem solar cells have gained significant attention as a viable commercial solution for ultra-high-efficiency photovoltaics. Ongoing research efforts focus on improving device performance, stability, and upscaling. Yet, paradoxically, their outdoor behavior remains largely unexplored. Here, we describe their performance over a complete calendar year outdoors in the area of the Red Sea coast of Saudi Arabia, which represents a hot and humid environment. After 1 year, our test device retains 80% of its initial power conversion efficiency. Further, we find three critical factors affecting current matching: the module temperature; deviations of the local, actual solar spectrum from the AM1.5G standard, which dictates optical design requirements of the subcells; and module soiling due to a spectrally non-uniform transmission of light through the accumulated dust. Overall, our results underline the promise of perovskite/silicon tandem solar cells as a future high-performance technology, yet device tailoring toward targeted deployment may be desired to achieve maximum energy yields.