The units aren't being mixed up, they're in both MW and MWh. 100 MW / 400 MWh refers to the storage capacity required to put out 100 megawatts for four hours. S

The units aren't being mixed up, they're in both MW and MWh. 100 MW / 400 MWh refers to the storage capacity required to put out 100 megawatts for four hours. Say you have a 100 MW solar facility, how much does it cost to keep the plant running 4 hours after sundown? That's what 100 MW / 400 MWh means. So sum this number with the cost of generation up on the chart above, and that's the net cost with storage. Nuclear doesn't need storage, since it's power output is not intermittent. The amount of wasted capacity varies with season, but minimum demand is usually 80% of peak demand. In the summer, this increases and the peak demand occurs during the day. This is a good place for solar: rooftop solar mitigating A/C is a great application of solar. But to fulfill base load, which is the vast majority of electricity demand, it is an ineffective choice.