Only three types of solar thermal power plants exist: linear concentrator systems, solar power towers and solar dish/engine systems. The most common form of solar thermal power plants – including those in California's Mojave Desert – is parabolic trough collectors. The troughs, also known as linear concentrator. The other form of thermal power plants is the solar power tower systems. This type relies on thousands of huge, flat sun-tracking mirrors, which. The third type of thermal power plants is the solar engine/dish. Compared to power towers and the parabolic troughs, solar engines are smaller.