A material’s color and shade affect the amount of light it absorbs or reflects; dark colors reflect less light to your eye, so they absorb more light. A “flat black” material having no glossy reflections absorbs the most solar energy. Conversely, light colors reflect more light than dark ones, and white reflects the most.
Metals such as copper and aluminum have an atomic structure that readily shares electrons; this gives metals high thermal conductivity, meaning that heat spreads rapidly through metallic objects. At the same time, many metals have melting points in excess of 500 degrees Celsius (932 degrees Fahrenheit), making them suitable for solar applications. Many solar installations harvest energy by converting sunlight to heat; metal components efficiently absorb and transfer heat while withstanding high temperatures. For solar applications that use mirrors, thin coatings of silver, aluminum and other metals serve as good reflectors of light.
Non-metallic materials such as brick stone and brick are good absorbers of solar energy, especially if they have dark coloring. Plastics and wood may make good energy absorbers, but many types are not suitable for solar applications because most plastics have relatively low melting points and wood may catch fire. With reflective coatings, however, plastic materials may be suitable for solar energy equipment, as long as temperature demands are modest. Clear glass and plastic absorb very little solar energy, so they make good lenses, windows and transparent enclosures .