Solar power has been growing at an exponential rate for the last several years. The interesting thing about exponential growth is that it isn't actually all that fast in its first stages, and easy to dismiss as meaningless. Once adoption really gets going, solar will become very large very fast.
I'm optimistic about solar too, but even if it looks exponential now, this doesn't tell you much about where it will level off. That will no doubt be determined by how cheap the panels become, and how cost effective storage technologies turn out to be.
