Mechanical device used in solar electric and solar thermal systems. Follows the movement of the sun (daily and sometimes seasonally) and keeps the energy collection device pointed directly at the sun. Allows for the harvest of the maximum available solar energy.

An automatic mechanical device that reduces the angle of incidence between a photovoltaic panel and the oncoming sunlight, thereby increasing the power of the solar radiation picked up by the panel and thus the amount of energy produced by it.