In the 1980’s, there was skepticism about the economic viability of cell phones. Now, most of the world’s poorest people can afford them. Today, the cost of fossil fuels is going up, while the cost of solar power is going down, and although solar power supplies less than 1% of global energy needs, the tipping point has already arrived in many developing countries. In the US, it could happen by 2020. A decade later, fossil fuels could be economically obsolete. We’ve heard such predictions before, and the transition will not be easy. Coal, Big Oil and public utilities won’t lie down. Government policies will be crucial. Will photovoltaic cells be the cell phones of the future? We look at the challenges posed by inevitable change in technology.