Arrangement and method at solar energy panels, heat-carrying wall sections and the like preferably as roof sections at greenhouses, having a plurality of parallel and in the same plane arranged transparent channels (2). One ends (3) of the channels (2) are connected to an inlet (4) and the opposite ends (5) of the channels are connected to an outlet (6) for supply and outflow of circulating heat absorbing fluid. The invention is characterized especially by said channels (2) being made into a continuous plate (1) being wholly transparent and that said fluid contains pigment particles for limiting of the light-permeability of the plate (1). The light permeability of the plate (1) can advantageously be adapted to for instance the light need of a cultivated plant by regulating the amount of pigment particles of the circulating fluid at the same time as the heat content of the fluid absorbed through the solar energy at least partly may be stored for heating of the cultivating space of the greenhouse during the period of the day when sunlight does not exist.
