The concept of solar tubes is very old and was even used by the ancient Egyptians. In the 19th century, the first commercial reflector systems using various forms of angled mirror designs were marketed in London. But not until the 1980´s did the solar tube system become popular for widespread residential and commercial use.
Solar tubes are a type of solar technology usually used for transporting or distributing natural light to brighten up dark rooms or corridors in a building. A solar tube can be integrated in a roof or floor to bring light into the room beneath. The entrance point of a solar tube often comprises a dome (cupola), which has the function of collecting and reflecting as much sunlight as possible. Some solar tubes have directional "collectors", "reflectors" or even fresnel lens devices to increase the amount of light that is collected.
The best light transmission efficiency is achieved when the solar tube is short and straight. Longer, angled, or flexible solar tubes have less light intensity. A high reflectivity of the solar tube lining is important to minimize light losses. Effective materials can have a reflectivity of 99%. Solar tubes capture light entering from any direction and diffuse it evenly into a room.
A solar tube can also be transparent, distributing light over its entire length or at certain points through controlled light leakage. Modern solar tubes provide natural light with a minimal heat loss, as they are contained in a sealed system.
Solar tubes are an innovative alternative to traditional skylights. They provide an efficient way of lighting an entire room and at the same time are environmentally friendly as there is no electricity needed and no solar panel necessary.