A solar energy collector panel intended for invisible incorporation behind and in thermal contact with a climate shield (94) of bituminous roofing felt or tar board on a building, said panel being made of a heat-conducting material and having at least one through- going fluid-impervious duct (91) embedded in said panel for passing a thermal energy carrying-capable fluid through it and having or being attached to a flat member (93) of heat-conducting material and substantial surface area intended to be mounted in direct physical contact with said climate shield. The solar panel provides excellent exploitation and transmission efficiency of sun radiation to an energy carrying-capable fluid in the fluid-impervious duct.