The coil coating process is ideal for specialty coatings used for solar energy because of the optimal surface prep, coating adhesion and continuous control that are unique to this process.
By using the coil coating process, thin coatings can be uniformly applied to metal strip so that a highly selective coating and several functional coats can be applied in very precise, thin layers. The functional coats often include functional particles, such as nanoparticles, metal particles, metallic oxide particles and pigments. Each coat has a job. For example, one layer may absorb short-wave solar radiation while also being transparent for long-wave radiant heat. The result is conduction of short-wave solar radiation converted into long-wave radiant heat, so that the absorber plate is heated up as needed. Outside coats can be reflective for radiant heat so that the absorbent coat emits little radiant heat to the outside. Additional coating layers provide humidity and temperature resistance to protect against corrosion. Other layers provide adhesion-promoter properties, which substantially improve the endurance of the coating in the intense sun.
With the coil coating process, the coating thickness can be adjusted precisely by means of the gravure on the roller coaters and relative speed of line. After coating, it is also possible to apply embossing to the painted metal in order to increase the absorbent surface without tears developing in the coating.
In addition, the coil coating process makes it possible to produce absorber panels at a much lower cost than previously necessary PVD or CVD processes.