The invention relates to a system for reclaiming solar energy in buildings, comprising a fluid inlet header pipe, a fluid outlet header pipe and a plurality of heat collector panels connected to the two pipes at ends thereof respectively. Fluid with a lower temperature from the fluid inlet header pipe enters into the heat collector panels, where it is heated to a higher temperature by the solar energy stored therein, and then discharges from the system via the fluid outlet header pipe for energy reuse. The heat collector panels are mounted on the inner surface of the cladding panels of the building, so that the outer appearance of the building will not be negatively influenced by the system.