Mark Z. Jacobson, professor of Civil and Environmental Engineering at Stanford gave a talk at the New School in 2012 about the economics of renewable energy.
His part of the talk starts at 18:50.
See also: his TED debate with Stewart Brand about nuclear energy.
Bloomberg on some promising trends in U.S. energy production.
For the first time, widespread adoption of renewables is effectively lowering the capacity factor for fossil fuels. That’s because once a solar or wind project is built, the marginal cost of the electricity it produces is pretty much zero—free electricity—while coal and gas plants require more fuel for every new watt produced. If you’re a power company with a choice, you choose the free stuff every time.
It’s a self-reinforcing cycle. As more renewables are installed, coal and natural gas plants are used less. As coal and gas are used less, the cost of using them to generate electricity goes up. As the cost of coal and gas power rises, more renewables will be installed.
See also: a wonky financial analysis of the residential solar market.