A system and method for harvesting solar thermal energy is disclosed. The system includes an absorption module, a storage module, and a flow control module. The absorption module retains a working fluid in a substantially constant volume and facilitates absorption of solar thermal energy in the working fluid. The storage module is fluidically coupled to the absorption module and is spatially positioned such that working fluid stored therein has higher gravitational potential energy relative to that stored in the absorption module. The flow control module permits passage of the working fluid from the absorption module to the storage module based on pressure of the working fluid in the absorption module exceeding a predefined threshold. When the working fluid transfers from the absorption module to the storage module, the thermal kinetic energy of the working fluid is transformed into gravitational potential energy thereof.