The Kassel University in Germany did a study on combining renewable energy sources for 100% power supply. The homepage is to be found at http://www.kombikraftwerk.de/index.php?id=27. The week point in the scenario is the lack of heat production that is strongly interact with the power production, also for a renewable power plant. I would recommend that the University in Kassel, utilized their own expertise from Prof. Klaus Vajen, an expert in solar heating, also large-scale.
The point of the study is, that it can be shown that the whole of Germany can be supplied with renewable energy. A simple statement, that lead me to the below memory:
Just to mention, similar scenario where made in the 80’th for the Nordic countries by among others the Technical University of Denmark, Niels I. Meyer.