Photovoltaic solar generation

technology · earth · global; manufacturing concentrated in China

The direct conversion of light into electricity in a semiconductor junction, and the clearest case in the energy system of a manufactured rather than constructed technology. The practical silicon cell dates from Bell Telephone Laboratories in 1954, at an efficiency of around six per cent and a cost that confined it to spacecraft for two decades. Commercial crystalline-silicon modules now convert roughly twenty to twenty-three per cent of incident energy, against a single-junction thermodynamic ceiling — the Shockley–Queisser limit — of about thirty-three per cent; laboratory perovskite-on-silicon tandem cells have passed thirty-four per cent by stacking junctions with different band gaps, which is how that ceiling is legitimately exceeded. What changed the technology's place in the energy system was not efficiency but price: module cost has fallen by roughly three orders of magnitude since the mid-1970s, and Chinese module spot prices fell below ten US cents per watt during the 2023–2024 manufacturing glut. The supply chain is the most geographically concentrated in the energy system — China holds a very large majority share at every stage from polysilicon through wafers and cells to finished modules, with the wafer share the highest of all. A PV plant has no moving parts, no fuel, no thermal cycle and almost no marginal cost, and it produces nothing at night.