If you can generate solar power 80% of daylight hours, that's a pretty good place to start.
Again, it's not an end-all-be-all solution. But you're talking about some very highly populated areas that could be using solar energy a hell of a lot more than they are now. Phoenix, Tucson, San Antonio, Dallas, LA, San Diego, Houston, Miami, Orlando, Las Vegas....that's a lot of places that could be utilizing solar power in a way that does move the needle. That's some 30-50 million people (if not slightly more) that could reduce their use of the federal grid in a measurable way.
I am optimistic that Santa Fe will soon see a new utility scale PV generation install that ought to generate power (with storage!) corresponding to roughly 1/3 of the city's residental use. The standard NIMBY-but-I'm-all-for-solar-have-some-myself crowd is out in force, however.
The OP appeared to be suggesting exactly that.
It's like the (many) solar advocates who pretend that a solar nameplate capacity of x watts is equivalent to a conventional nameplate capacity of x watts, when in fact you're going to need 2x watts at a minimum, with an expensive storage system on top of that.
Your last paragraph is something different -- that's not an implication that solar can generate at night. Note that levelized cost of energy does take into account that consideration (that why it's "levelized"). And renewables are trouncing new construction nuclear on that metric.
Nobody is pretending that solar can provide electricity via night time generation. That's what storage systems and alternative sources are for.
The daylight story in ABQ is this:
> "It is sunny 78.9% of daylight hours. The remaining 21.1% of daylight hours are likely cloudy or with shade, haze or low sun intensity. "
http://www.albuquerque.climatemps.com/sunlight.php