Abstract: The invention relates to cooling element (5) having a fastening device (16) for upgrading any standard, commercially available photovoltaic module (1) for increasing the efficiency of the photovoltaic module (1). According to the invention, it comprises a heat insulation mat (6) having an upper surface (7), in which pipe channels (8) aligned parallel with each other are created, wherein the borders of the pipe channels (8) and the upper surface (7) of the heat insulation mat (6) are constructed with heat conduction plates (9), preferably aluminium plates. It further comprises a pipe (10) that is routed in loops (11) in all of the pipe channels (8) constructed with the heat conduction plates (9). The invention also relates to a method for attaching a cooling element (5) according to the invention to a photovoltaic module (1).