[pornel]

The demand for energy is highly variable. Without storage, the production capacity has to be overbuilt to match the peak demand, and then sit underutilized for the rest of the day.

Even with just fossil fuels, it's preferable to build a smaller power plant that runs 24/7 than invest bigger money in a bigger power plant and then operate it only some of the time.

See "duck curve".

[Mrdarknezz]

No you don't have to overbuild? Just build enough load following.

Storage will waste massive amounts of energy through conversion