The key barrier in solar and wind technologies is that they are not 24/7 reliable sources of energy.
Sometimes the sun does not shine even in the middle of summer in Nevada’s desert.
Sometimes the wind does not blow even in the middle of winter on top of a mountain.
The power utilities have a mandate to provide constant power. They cannot rely on solar and wind to do that.
For example, the power utilities say they need another 20,000 units of energy during peak summer demand months 5 years from now.
They build a solar thermal plant to generate 20,000 units during the summer.They will still need to build or expand a coal, natural gas or nuclear plant to also generate 20,000 units because there is no guarantee that sun will shine every day in summer. They must have a backup system.
So we will duplicate the capital cost and labor to run both systems. Also, we will have to spend a large amount of money to build high power lines from the solar plants to the cities. The reason for that high cost is land.
Read more at http://www.desertconservative.com/2008/08/04/solar-and-wind-capital-and-labor-cost-duplication/