I can't find the source but I remember an article thatdiscussed the rate solar energy is adopted. The researchers made lower and upper bound predictions, and what if all solar PV development stopped immediately. The worst case scenario based on availabile data suggested a three fold increase in solar PV electricity generation, the number used by the article you cited, to a best case scenario of solar PV increasing to the power of three, really big exponential growth. Now the optimistic model seemed a bit too optimistic for me, but it at least suggested that there is a lot more capacity to build out solar PV. If that capacity is realized or wasted was the biggest unknown factor in that study, which like duh. Still, I took it to mean that the future will probably be a little bit more optimistic than the most pessimistic projections. It's a small comfort.