ClimateWire: On paper, the amount of sunlight hitting the Earth in one hour could fulfill humanity's energy needs for a year, an equation that's hard to ignore.
However, harnessing more of this vast potential remains a major challenge, since the sun has to compete with coal, oil and natural gas -- fuels that are abundant and cheap and retain substantial political support in many parts of the world, including the United States.
Over the past few years, solar energy technologies, particularly photovoltaics,...