"Wind and solar power now provide the least-cost options for electricity generation in windy and sunny regions of the USA, even before accounting for subsidies and environmental impacts (Lazard2017). Wind and solar also yield substantial benefits for climate, air quality, and health when replacing fossil fuels (Jacobson2008). However, the variable nature of wind and solar power production limits their ability to displace fossil fuels. Aggregating multiple intermittent generators whose output differs temporally can reduce the uncertainty and variability of their output (Hart et al.2012). Reduced intermittency can be achieved by aggregating multiple wind farms (Kahn1979) or by combining the output of wind and solar farms (Zhou et al.2010)."