According to your article, you can get subsidies in some places for up to 2/3 of the cost. If the wind is also good, you get a payback of 5 years or less. So the payback on the unsubsidized cost with good wind is probably 12-15 years. Wind turbines typically have a 20 year life, so a 12 year payback (the best case scenario) corresponds to a 5% Internal Rate of Return (IRR.)

Companies usually expect a minimum IRR of 15% to 20% before they will invest in a project. That would require at least a 6 year payback (with subsidies, after paying for transmission.) Not only are large scale wind subsidies smaller than small wind subsidies, large wind farms sell power at wholesale rates, which are typically 1/2 to 1/3 the price that a net-metered small wind generator gets.

In other words, the economics of small wind are probably about 1/3 as good as the economics of large wind. Subsidies can make up the difference, and that’s why they are larger for small wind.