Specific cleaner for the removal of charred residues of antifreeze fluids due to thermal stagnation. Ideal both for the cleaning of solar panels in which charred residues are encrusted and the general cleaning of the whole solar circuit in which the antifreeze fluid has been subjected to pH lowering, decrease in the heat exchange capacity, viscosity increase. Compatible with all kinds of metals usually employed in heating systems including aluminum. Not compatible with galvanized steel.