Solar PV, on a truly useful national scale in the US, rises and falls with the technological ability to harmoniously integrate it -- all green power really -- with brown (coal, natural gas, nuclear) power.
There's a lot of talk out there about "The Smart Grid," though a lot of the articles, comments and "reports" fail to provide hard numbers (how many trillions of dollars, frankly) on what it would take to set up a nationwide electrical grid into which renewable energy producers (any Joe with with Solar PV array, or any "solar farm") can productively plug in. Productively in the sense that Joe profits from selling his Solar PV array's power and consumers -- hence, the nation -- benefits without subsidizing him (that is, it buys from him at a free-market price and not at an inflated, subsidizing price).
I'm collecting "National Smart Grid" data on this page. Please email me at firstname.lastname@example.org if you find something useful.
Solar Power Micro-Grids, at utility scale. Click here.
Non-national "Smart Grid" articles and articulations:
A "Smart Grid Plug & Play" conference.
A downloadable, 2011 Global "Clean Energy Progress Report" that delves into Smart Gridding somewhat. Here's the .pdf.
Here's a woman who talks about it but proposes basically nothing except to end brown power subsidies.