If solar is less expensive than the available clean conventional sources then this might make sense. Otherwise, why bother? It's only in situations where you're already near existing daytime conventional capacity and the deployment of solar is much faster/cheaper in the short term than deployment of another clean conventional source that it might make sense. But if solar is expensive and/or time-consuming to deploy (relative to deploying another clean conventional source) then it simply doesn't make sense to use it even if it's only for dealing with peak load.

Forgive me, but you are completely wrong about this. Peak periods are exactly when things like solar really "shine." There are a couple thing you must understand about the interstate electricity grid:

First, is that it is over-designed on purpose. Most major utilities have operating reserves of power generation of between 12 - 18 % of the day's anticipated peak demand. On any given day, the system operator will have tens or hundreds of generation sources that it never dispatches (e.g., uses to produce power), but that are there "just in case." This means that utilities have multiple dispatch solutions in order to meet load (load being a measure of people who want to use electricity).

The second key principle is that utilities select their generation resoures based on a "least-cost dispatch" basis. While in practice, this gets incredibly complicated (and also includes environmental factors), the utility will pick the least expensive generators that can produce enough power to adequately supply the day's demand. In practical terms, this means that the utility will dispatch the dirtiest and most expensive to operate (on an incremental cost basis) generating facilities last.

The third principle is an outgrowth of the first two. On peak demand days (think middle of summer, air conditioners running at full blast, etc.), the number of dispatch options available to the utility decreases further and further as it commits an ever-increasingly greater share of its total generating capacity to meet demand. This means that your nastiest, dirtiest, foulest, most expensive generating facilities are dispatched on such days.

Imagine this scenario. You are Utility X. You have the following five generating facilities at your disposal:

1000 MW nuke.

500 MW cheaper, clean(er) coal.

500 MW slightly less cheap dirty coal.

100 MW incredibly expensive natural gas.

20 MW aging oil burner that spews out more toxics that Paris Hilton on a breathalyzer AND costs more than the GDP of small nations to operate.

Total installed capacity (a fancy term for the total amount of generation): 2110 MW.

Now imagine that hellishly hot day. Demand immediately soars to 1500 MW -- and it's not even 11 am yet. You commit your nuke and your clean coal facility. Now it's 2 pm and demand hits 2000 MW. Throw in the dirty coal. Four pm rolls around and de... [ Read More (0.3k in body) ]