Abstract: A system for heating and cooling of environmental spaces, the present invention efficiently utilizes collected solar energy, the solar energy being stored at least partially in a phase change heat storage material. The collected solar energy can be utilized directly as an input into a heat pump evaporator, the heat pump sub-system being also utilized for direct expansion cooling. The present system particularly allows the utilization of lower temperature solar energy collection media due to the presence in the system of a heat pump, thereby resulting in greater solar collection efficiency due at least in part to lower heat conductive losses.