There have been hundreds of forecasts of the future costs of solar power and the projected share solar power would have in the future. Ramez has been an optimist around solar energy and solar energy development but actual development has even exceeded his previous forecasts in 2011 and 2015.
Ramez Naam has new forecasts that use something like Wright's law. Wright's law has been used by Ark Investments to predict the cost reductions in Tesla electric cars and batteries.
T.P. Wright saw that doubling of scale led to a constant percentage reduction in cost in 1936 while studying the production costs of airplanes. This relationship between cumulative production and cost has been found in other areas like smartphones, computers and other products.
Solar Energy costs have dropped by a factor of 5 since 2010. Utility-scale solar energy is around 4-5 cents per kilowatt-hour. The lowest cost solar project bids are at costs of 1.35 cents per kwh in Abu Dhabi or 1.6 cents per kwh in Portugal. Solar in 2020 is: