How about deploying a cluster of "umbrella" satellites to throw some shade on regions of the planet that get too hot? 15 years of having less solar illumination

How about deploying a cluster of "umbrella" satellites to throw some shade on regions of the planet that get too hot? 15 years of having less solar illumination, not complete darkness just a penumbra, could maybe do a lot. How big of a shadow would we need? Edit - someone already thought about it; http://www.bbc.com/future/story/20160425-how-a-giant-space-umbrella-could-stop-global-warming http://www.bbc.com/future/story/20160425-how-a-giant-space-u...