The pace of solar energy development is accelerating as the installation of rooftop solar water heaters takes off. Unlike solar photovoltaic (PV) panels that convert solar radiation into electricity, these “solar thermal collectors” use the sun’s energy to heat water, space, or both.
China had an estimated 168 million square meters (1.8 billion square feet) of rooftop solar thermal collectors installed by the end of 2010 — nearly two thirds of the world total. This is equivalent to 118,000 thermal megawatts of capacity, enough to supply 112 million Chinese households with hot water. With some 5,000 Chinese companies manufacturing these devices, this relatively simple low-cost technology has leapfrogged into villages that do not yet have electricity. For as little as $200, villagers can install a rooftop solar collector and take their first hot shower. This technology is sweeping China like wildfire, already approaching market saturation in some communities. Beijing’s goal is to reach 300 million square meters of rooftop solar water heating capacity across the country by 2020, a goal it is likely to exceed.