A reciprocating solar engine includes a) a seesawing platform having a central fulcrum support upon which the platform is moveably positioned to reciprocally rotate through a predetermined arc b) a first solar heat-receiving closed container located on the platform on one side of the support and a second solar heat-receiving closed container located on the platform on a second side of the support; c) a connecting tube connecting the first container and the second container; d) a fluid contained within at least one of the first and the second container, the fluid being evaporable from solar heat and condensable from shading from solar heat; e) a roof above the platform, having at least one window of which is located above the first container and at least one window of above the second container; f) shuttering devices connected to the roof and movable so that one window is closed while the other is open and vice versa; and, g) shutter device controls functionally connected to the shutter device and the platform such that the shutter device controls activate the shutter devices to a first rest position when the second solar heat-receiving closed container is at its arc base, and to the second rest position when the first solar heat-receiving closed container is at its arc base.