In addition to the reinforcement and extension of the grid, the need to cover strongly varying residual load would not only continue to generate long-run adequacy costs but also impose added ramp costs on dispatchable operators. The latter have not been accounted for explicitly in this study due to data issues but have been qualitatively discussed in the context of load following of nuclear plants and should not be neglected in a more complete analysis. For instance in California, where peak demand is reached in the middle of the day due to air conditioning, solar power, which reaches its maximum contribution with some regularity during almost the same hours, has a relatively high capacity credit (this rather favourable situation in California and the south-western United States cannot be extrapolated to the rest of the United States).