Solar energy is large in total quantity reaching a wide area, but it is thin energy having a small energy density. For its use, there is a need for collection of light or collection of heat. Ideal light selective absorption films excel with increasing absorptance (α) in the solar wavelength region (0.3 - 2.5μm) and decreasing emissivity (ε) in the infrared wavelength region (3.0 - 20μm).
In consideration of thermal stability, black nickel plating and black chromium-based plating have excellent light selective absorption.
| Type of plating | Characteristic value | Uses |
|---|---|---|
| Black chromium plating | - Absorptance (α): 0.90～0.96 - Emissivity (ε): 0.11～0.16 |
Various uses of solar heat/air-conditioning, hot-water supply equipment |
| Black nickel plating | - Absorptance (α): 0.91～0.94 - Emissivity (ε): 0.07～ 0.11 |
(From “Kino Zairyo Nyumon,” Motofumi Honma, et al., Agne)
Black chromium plated solar collector
(From “Denki Mekki Gaido” edited by Federation
of Electro Plating Industry Association, Japan)
Types of plating
