[ResearchAtPlay]

Efficiency improvements amplify cost reduction per kWh electricity: An ever growing share of PV system costs stems from every item that is not a a module (inverter, cables, labour etc). Modules are becoming cheaper faster than other components, so reducing module costs further has diminishing returns.

In contrast, taking your module efficiency from 20% to 21% increases electricity generation by 5% and thus reduces costs per kWh by 5%.