By far the largest solar thermal market in the world according to newly installed solar thermal capacity per year is China. In 2008, around 21 GWth (30 million m2) were sold in China, which was around 80 % of the world global solar thermal market.
There are a number of mature markets like Israel, Austria, Barbados, China or Cyprus where solar thermal is used by a wide majority of people for heating the domestic hot water and sometimes for room heating.
Generally speaking, you can differentiate between naturally growing markets and incentive driven markets. In the former, low-cost solar water heaters are already an economic alternative for households to produce hot water instead of using fossil fuels or electricity. Some examples are: China, which is the biggest solar thermal market in the world, Cyprus which has one of the highest solar thermal capacities in operation per capita in the world, and Turkey, which is the third biggest market in the world.
The Mojave Desert in California will be the host for the largest solar power project in the world with 553 MW installed capacity. The Mojave Desert already HAS nine solar power plants in operation, summing 354 MW.