I don't know the calculation either, and have been trying to get hard numbers on various potential large scale storage such as https://en.wikipedia.org/wiki/The

I don't know the calculation either, and have been trying to get hard numbers on various potential large scale storage such as https://en.wikipedia.org/wiki/Thermal_energy_storage https://en.wikipedia.org/wiki/Thermal_energy_storage and Lithium ion, as well as some sort of learning curve for costs. So far I've found a pretty compelling and well backed case for solar, but the storage component is always hand waved.