Improving Energy Yield of Triple‐Junction Solar Cells With a Parallel‐Series Configuration

Multijunction solar cells (MJSCs) offer power conversion efficiencies far beyond the 33.2% limit of single‐junction solar cells, with a theoretical limit of over 50% for triple‐junction cells. Monolithic (two‐terminal) MJSCs involve series connections between the junctions. The simplicity of only requiring two electrical terminals comes with a cost of electric‐current‐matching. This is difficult to achieve in practice when the spectrum varies, thereby reducing performance in real‐world conditions. While mechanically stacked MJSCs overcome this difficulty, they introduce additional electrical terminals (e.g., six terminals for mechanically stacked triple‐junctions). Our proposed three‐terminal (3T) parallel‐series triple‐junction solar cell offers a promising blend of series‐ and parallel‐connected junctions. We show that this hybrid design demonstrates a theoretical efficiency advantage of nearly 20% over conventional monolithic tandems under overcast conditions and increases the annual theoretical energy yield by up to 9.6% in cloudy and high‐latitude locations. This advantage remains when the junctions do not suffer from low () R _SH and operate above 25 °C, and when the bottom junction is switched from silicon to germanium or metal halide perovskite. These results highlight that this hybrid design represents a promising and practical pathway toward more robust solar cells, delivering high efficiencies and energy yields under the nonideal spectral conditions faced in the real world.