A solar heating panel unit is provided in the form of a plastic pouch having an internal chamber provided with a serpentine path. The pouch has two sides, one of which consists of a layer of anti-abrasive matte black plastic and a sealant inner layer of black medium density polyethylene film. The other side incorporates a reflective layer of aluminum foil. The pouch has inlets and outlets, whereat hardware fixtures are employed, consisting of threadably engaged parts having flanges between which is clamped a wall of the pouch. The pouch, or a plurality of such pouches, may be incorporated into systems wherein a cold water source is connected selectively through the pouch to a tank or through a boiler, whereof the boiler or the tank supplies a construction requiring heated water. Alternatively, the system may be such that the tank is excluded.