[colechristensen]

The question is if you could build and operate a smaller plant to run at 100% capacity at all times which includes energy storage for less money.

You either have losses in:

* Underutilized solar generation

* Underutilized plant capacity

* Overhead of energy storage

Design your system to minimize that cost. Engineering systems of all sorts are full of this kind of optimization problem: "Should I add a subsystem to recover loss x?" There is always more you can do to recover losses, but each extra system you add suffers diminishing returns a little more.