Zero to One: Notes on Startups, or How to Build the Future · chapter 12 · id zero-to-one-c12-08-solar-panel-efficiency-improve

“Solar panel efficiency improved only ~25-40% (from ~16% to ~22%), nowhere near the 10x improvement Thiel says is needed for breakthrough technology.”

contestedconfidence: high⚠ extracted by pipeline, re-audit pending

Receipts

Fraunhofer ISE -- Photovoltaics Reportsource alive
Commercial silicon module efficiency increased from ~17% to ~21% by mid-2010s. Module prices fell from $4/W in 2008 to under $0.80/W by end of 2013.
Swanson's Law -- Wikipediasource alive
Solar PV module prices fell from $76.67/watt in 1977 to $0.36/watt in 2014 -- a 200x cost improvement driven by manufacturing scale, not lab efficiency.

This claim is a stable, citable object. If you can falsify a verdict, tell us — corrections are loud here.