A modular panel for thermal energy transfer particularly configured for being used in ceilings and walls, comprising a heat-insulating layer forming a supporting structure demarcated by at least a lower face, an upper face, two side faces (2C, 2D) and two end faces (2E, 2F), the panel further comprising at least one conducting plate attached to the lower face of the heat-insulating layer, wherein said conducting plate is formed by: • a groove embedded in the heat-insulating layer defining a longitudinal cavity which is configured to house a hydraulic pipe, said groove in turn being finished by two longitudinal edges which are flush with the lowerface, defining a longitudinal opening which is configured to allow inserting the hydraulic pipe; and • a transfer plate prolonging from at least one of the longitudinal edges and extending on the lower face; and closure means configured to seal the longitudinal opening and press the hydraulic pipe against the groove, characterized in that the closure means comprises: • a longitudinal embossment having a toothed profile arranged in each of the longitudinal edges of the groove of said conducting plate; and • an elastic closure element configured to compensate for the expansions of the hydraulic pipe caused by temperature changes thereof, wherein said closure element is formed by: ∘ two longitudinal sides having a toothed profile fitting with the longitudinal embossments to allow securing the closure element to the conducting plate and sealing the longitudinal opening, assuring the leak-tightness of the longitudinal cavity; ∘ a longitudinal seat which is configured to press the hydraulic pipe against the groove, assuring the thermal energy transfer between the hydraulic pipe and the conducting plate; and ∘ a lower base which is flush with the lower face. • a groove embedded in the heat-insulating layer defining a longitudinal cavity which is configured to house a hydraulic pipe, said groove in turn being finished by two longitudinal edges which are flush with the lowerface, defining a longitudinal opening which is configured to allow inserting the hydraulic pipe; and • a transfer plate prolonging from at least one of the longitudinal edges and extending on the lower face; and closure means configured to seal the longitudinal opening and press the hydraulic pipe against the groove, characterized in that the closure means comprises: • a longitudinal embossment having a toothed profile arranged in each of the longitudinal edges of the groove of said conducting plate; and • an elastic closure element configured to compensate for the expansions of the hydraulic pipe caused by temperature changes thereof, wherein said closure element is formed by: ∘ two longitudinal sides having a toothed profile fitting with the longitudinal embossments to allow securing the closure element to the conducting plate and sealing the longitudinal opening, assuring the leak-tightness of the longitudinal cavity; ∘ a longitudinal seat which is configured to press the hydraulic pipe against the groove, assuring the thermal energy transfer between the hydraulic pipe and the conducting plate; and ∘ a lower base which is flush with the lower face. ∘ two longitudinal sides having a toothed profile fitting with the longitudinal embossments to allow securing the closure element to the conducting plate and sealing the longitudinal opening, assuring the leak-tightness of the longitudinal cavity; ∘ a longitudinal seat which is configured to press the hydraulic pipe against the groove, assuring the thermal energy transfer between the hydraulic pipe and the conducting plate; and ∘ a lower base which is flush with the lower face.