:

Over the last few years solar PV has got cheap. Cheap enough to start impacting some commodity energy markets today. Cheap enough that with continued progress, but no breakthroughs, it might alter the global outlook for energy supply within a decade.
 
 I have long been skeptical of solar hype. In 2008 we did an expert judgment exercise suggesting only even odds of getting to module prices of 0.3 $/W in 2030. In 2011 we did some analysis showing how the power-law learning curve for modules appeared to be flattening. That analysis was done at the end of a decade that saw big increases in installed capacity, with little corresponding change in module prices. The solar market was driven by incentives, like tax credits and feed-in tariffs that drove rooftop solar seem systems which are (arguably) little more than green bling for the wealthy. I worried that deployment incentives (global total amounting to many hundreds of billions of dollars over the past decade) would simply lock in the current technologies and do little to drive the breakthroughs that were needed to get solar cheap enough to compete for commodity power.