I asked the folks at Enphase if they had data on the total output of their installed systems over time (which report back statistics via a buy-back-your-data sort of subscription arrangement)  This is what they came back with.  Pretty impressive growth, whether it reflects overall solar growth or growth of this one company’s installations!  Almost 5 gWh in Sept 2010 is nothing to sneeze at.  Most must be in the northern hemisphere, you can see the seasonality of power production start to kick in….

Other neat visualizations of Solar PV growth in the US can be found NREL’s OpenPV site.