The largest uncertainty about renewable energy is the two kinds of technology risk. Like with all new technologies, renewables have a productive life of uncertain length. This is especially problematic when renewables are replacing proven electricity assets with 30, 40, or 50 year lifespans. Not unimportantly, the transition to renewables creates billions and billions of dollars of stranded costs
In addition, I know of many early adopters, businesses, and offshore wind farms, which are no longer being the provider of the renewable electricity that was expected from them, either from product failure or expensive maintenance problems.
Then, there is the other side of technogical risk, which is the risk of newer renewable technology making the old technology obsolete prematurely, which creates its own billions and billions of stranded costs. You also will notice there is no discussion of the cost of new transmission configurations.