You are referring to Wright’s Law [1]. For more than four decades, the price of solar panels declined by 20% with each doubling of global cumulative capacity[2

You are referring to Wright’s Law [1]. For more than four decades, the price of solar panels declined by 20% with each doubling of global cumulative capacity[2], but you should check that with many more data sources, especially reputable or scientific sources. [1] https://en.wikipedia.org/wiki/Experience_curve_effects https://en.wikipedia.org/wiki/Experience_curve_effects [2] https://ourworldindata.org/learning-curve https://ourworldindata.org/learning-curve