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I wasn't arguing for all his calculations, it's just that his evaluation of the theoretical limit of crystalline silicon cells is accurate. He is correct that i

I wasn't arguing for all his calculations, it's just that his evaluation of the theoretical limit of crystalline silicon cells is accurate. He is correct that it is unlikely that they will get much closer to the theoretical limit than 20% in real life situations. Some GenIV nuclear reactor technologies have a somewhat clearer path to viability than multi-junction solar cells, which have not been able to beat traditional cells in a price-to-performance ratio. We don't even know if there exist materials and processes that can replicate the performance without the costs; see high temperature superconductivity for a technology that's been stuck at that stage for a while, even in the face of the helium shortage.

selimthegrim 11y ago
There are multiple well-attested routes around the Shockley-Quiesser limit most of which do not involve just silicon. One, which MacKay touches upon, is multi-junction systems. Another, which he does not (not being an expert in the field) is via so-called multiple-exciton generation systems. Contrary to most engineers' understanding, this phenomenon is pretty well explained from the point of a low-energy continuum QFT for the materials that most care about for implementation. The real game changer would be to mate these systems with topologically nontrivial materials with surface charge transport protection. Unfortunately with current fabrication capabilities, 70% of the conductivity is in the bulk, which does not possess the topological prohibition to one-particle (or one e-h pair) backscattering. (It would also be interesting to see if the known allowability of 2 particle backscattering applies to excitons in these systems)