Central receivers (or “power towers”) are types of solar
thermal systems that use mirrors to focus sunlight to a focal
spot (in this case a tower) [6]. But instead of using a dish to
harvest solar power, central receivers rely on a stationary
tower and nearly flat, tracking mirrors (heliostats) arrayed
around the tower [7]. Each heliostat in the array is freestanding,
and is able to independently track the sun [8].
Inside the receiving tower, a heat transfer fluid (usually
water or molten salt) absorbs the sun’s thermal energy and is
used to generate steam for a turbine [9].