Solar Thermal Power
Solar thermal generation of electricity uses sunlight to heat a working fluid which in turn moves an electro-mechanical electricity generator. Typcially, sunlight is concentrated by high ratios onto fluid-containing receivers using heliostats -- mirrors or other optics mounted to track the sun's seasonal and daily movement across the sky.
Solar thermal generation methods are used almost exclusively for industrial-scale plants, in contrast to photovoltaic panels or concentrating photovoltaic systems, which are used in installations of all sizes.
Although many arrangements of mirrors and receivers are possible, most operational solar thermal plants employ one of the following designs:
- Parabolic trough: Reflectors shaped as parabolic cylinders, each continuously positioned by a one-axis sun-tracking mount, focus sunlight on tubes running along the reflector's focal lines.
- Power tower: Scores of flat reflectors, each continuously positioned by a two-axis sun-tracking mount, focus sunlight on a common receiver elevated atop a tower.
- Parabolic dish: Parabolid dishes, each continuously positioned by a two-axis sun-tracking mount, focus sunlight on receivers located at their respective focal points.