[mrbabbage]

This doesn't answer your question about residential solar, but it's a useful primer on economic analysis for utility-scale operations.

http://www.eia.gov/forecasts/aeo/electricity_generation.cfm

The interesting bit here is how wind is already cheaper than any other option save combined cycle natural gas, and wind is on track to surpass natural gas.

[kefka]

I've been interested in the viability of those wind towers. The ground is blanketed with plastic tarp about 10ft above ground. It slowly tapers to vertical (approximates y=10^x curve). In the vertical section, there is a scaffolding with wind turbines.

The idea is that the sun heats up the ground. When the wind starts moving, it goes up the chute, spinning the blades.

It was theorized that a 1mile diameter ground cover + tower would give 500 MW of power.