Two things struck me today.
First, I read Bloomberg Green's daily newsletter (Nathaniel Bullard) and came across the following statistic. In 2001, the world installed 290 megawatts of solar generating capacity. This year, the world is likely to install more than 100 gigawatts of solar -- that's 350x more per year than we were installing 19 years ago. You can also see how things have changed by looking at the above chart showing wind and solar asset financing per year.
Second, I read about Fred Wilson's SunPower Solar system and how, since May, he has been able to satisfy 91.5% of his home's electrical needs via solar (this includes an electric vehicle). In fact, during the month of May when temperatures were a bit cooler, he had a surplus. He was producing more than he was consuming, and so he was selling that excess production back into the grid. It wasn't until the summer months and higher AC usage that he started having a shortfall.
Now I don't know where his house is located or what its roof looks like, but it is interesting to consider both the macro and micro scale. 91.5% signals to me that it shouldn't be much longer before many people and many homes no longer need to draw any power from the grid. That's going to be a game changer.
Chart: Bloomberg Green