I'm not sure what took so long, but the dramatic drop in solar panel prices in the past few years surely helps to make such a project much more affordable and competitive. (treehugger.com)
It shows the drop in solar panel prices over 36 years. (treehugger.com)
Solar panel prices continue to drop, making them more and more competitive with coal or natural gas power plants for electricity generation. (thecollegeinvestor.com)