The minute human beings began chipping stone tools we became a technological species. Just prior to the invention of the steam engine, Europe had thousands of water wheels powering manufacturing machinery of various types. A nascent solar power industry also existed but was cut short by the realization stored solar power in the form of coal was more economical to exploit. Assuming that the human race survives the coming energy transition, there is not the remotest possibility that we will become a non-technological species. The key questions are:

1. What level of economic production can be sustained in post fossil fuel world containing 8 or 9 billion people?

2. How long can the world’s net economic productivity continue to increase?

It is not just the sustainability of solar PV that matters, but economic cost of delivering a net unit of energy, including the cost of compensating for the variable nature of the solar resource on both short and long time scales as dispatchable fossil fuel generation declines. Since China is still building coal fired power plants like crazy, it is clear that solar energy has a ways to go yet before it can match the economic quality of fossil fuels.

Furthermore, no matter how much solar energy technology improves in the future, it cannot enable the exponential expansion of our economic productivity forever. When the world’s net economic productivity stops increasing, then new ways of allocating production resources and more equitable means of distributing economic output will have to be developed if we hope to maintain a humane, democratic society. I believe that the dream of purely technological fix which will enable business as usual operation of the current economic system to the end of the century and beyond, will prove delusory.