BackgroundSolar heat
We understand the option “solar heat” or solar-thermal to mean using heat from solar radiation. This is in contrast with directly converting photons from sunlight into electrons, as occurs in photovoltaic conversion (solar-PV, or solar cells). Solar-thermal installations need direct solar radiation, where the photovoltaic conversion can also make use of diffuse light. With solar-thermal systems, it is sometimes a matter of directly using the absorbed heat, and sometimes that heat is an intermediate step in producing electricity, for example.
There are plans for large-scale projects for combining sunlight across a large surface area (concentrated solar power, CSP). In regions with high sunshine levels like Spain, the United States and Australia, arrangements are being tested for optimum use for driving steam turbines. Here, solar radiation is concentrated with the use of mirrors and radiated onto a fluid medium (oil) that transfers the heat to a steam circuit, which drives turbines for generating steam.
There are also experiments going on with artificial airflow caused by temperature variations. This idea is being applied in a so-called “solar flue” hundreds of metres in height. The rising air in the flue drives the turbines directly.
