GENEVA, 2031 — On a Tuesday in late September, the spot price of electricity on the European grid touched zero for the first time in history. It stayed there for eleven hours. Grid operators initially flagged it as a sensor error. It wasn't. --- The story of how solar became effectively free is not one invention — it's compounding. Panel efficiency crossed 40% in 2027. Battery storage costs dropped 90% from 2020 levels by 2029. The buildout fed itself: cheaper energy made manufacturing cheape
