That math doesn't work -- at least until someone can demonstrate cost effective grid scale energy storage systems. In other words it is not cheaper and perhaps not greener (it isn't clear how green the production and long term maintenance of solar/wind is)

The basic problem is that in order to provide reliable energy 365 days a year you need to account for the daily and \ seasonal variability of solar and wind. You have two options:

    * maintain a duplicate fossil fuel backup system (fully maintained, staffed, and fueled) for those cold windless nights (so no longer cheaper)
    * deploy a storage system that can effectively time shift energy created by solar and wind across entire seasons (also not cheaper nor demonstrated with current battery technology)

Of course if you don't care about reliable electricity you have one more option:

    * suck it up when there is no sun or wind available