The photovoltaic sector is now led by silicon solar cells because of their well-established technology and relatively high efficiency. Currently, industrially made silicon solar modules have an efficiency between 16% and 22% (Anon (2023b)).
The theoretical limiting efficiency of the crystalline silicon solar cell under non-concentrating sunlight is about 29% . This is not far below the theoretical limit for any single junction solar cell.
However, costs per unit area are orders of magnitude higher than for crystalline silicon cells. The best laboratory and commercial silicon solar cells currently reach 24-25% efficiency under non-concentrated sunlight, which is about 85% of the theoretical limit.
Silicon solar cells have a limited ability to capture low-energy photons, which limits their efficiency, especially in low-light conditions. Moreover, the practical limits in obtaining maximum efficiency are restricted by many factors including different types of recombinations and losses (Shah et al., 2004).
Improving the efficiency of silicon-based solar cells beyond the 29% limit requires the use of tandem structures, which potentially have a much higher (~40%) efficiency limit. Both perovskite/silicon and III-V/silicon multijunctions are of great interest in this respect.
Since then, experts have considered that 25% was just about the practical limit for monocrystalline silicon solar cells 4 – 6. Now, writing in Nature Energy, Kunta Yoshikawa and colleagues from the Kaneka R&D group in Japan have demonstrated a new record efficiency of 26.3% monocrystalline silicon solar cells over a large area (>180 cm 2; ref. 7).