One of the major obstacles for introducing renewable energy power to general consumers is the problems that come with electric grid integration, due to the specific regime in which renewable energy sources can be exploited (intermittance, energy storage). The latest NERC (North American Energy Reliability Corporation) report says large-scale renewable energy will require a different approach in the way the power system is planned and operated. The report "Accommodating High Levels of Variable Generation" was released on April 16, and highlights transmission additions, reinforcements, better forecasting of variable generation output, and access to flexible grid resources. These have been identified as key contributors for reliably integrating variable power resources into the electric grid.

With a significant amount of wind energy coming to the market, as well as the future expected growth of solar power, this report comes at the right time to push things forward. Much research is going to have to be done, for example on technical issues like power flow and stability modeling, but also consistent and reliable forecasting of variable resource availability.

If you want more specifics, see a more detailed outline of the report, as well as some specific recommendations.