I should note a couple other things:

The $0.50 I quote above for diesel electricity generation is a lower bound. Actual costs extend up to $2.00/kwh.

I'll also add that the reason solar is a poor fit for peak demand is twofold:

1) Sure, you can install a solar panel which does nothing but feed electricity into the ground when not needed - rather than have a diesel generator. This increases the cost per utilized kwh for solar, however. Peak demand is, by definition, a rare occurrence. How much economic sense does it make to install a full time electricity producing capital good in order to meet a 5% or less situation?

2) The demand profile for electricity is changing. With the addition of electric cars into the mix, it can no longer be safely assumed that peak electricity usage coincides with hot days in Southern California/Nevada. A peak electricity usage might instead by a holiday weekend where everyone charges up to drive to Grandma's house - and if that day is cloudy, then we'll have to fire up the diesel generators.

Equally the notion that electric cars' batteries can be an off-grid storage medium. This is even more ridonkulous.

If an electric car had sufficient range that an owner could drive it for 2 week's or more normal driving - which is what a gasoline car does - then the above statement might be true. However, if the range of electric cars is only 2 or 3 days worth, then there is no storage capacity to speak of.