Solar water heating is done with devices called solar collectors. Solar collectors collect solar energy and then transfer this energy as heat. Thanks to this heat, it is used during heating with solar energy or obtaining hot water. The solar collector, which has a long life with its non-wearing structure, has a simple operating system.
Solar collectors are placed at a fixed angle, depending on the latitude of the place where the application is made, in such a way as to receive the solar maximum. Collectors connected at the right angle can reach temperatures up to 100°C. The resulting heat is transferred to the heating devices by means of other devices.
We can examine solar collectors that convert solar energy into heat energy in three groups. These are the plain, parabolic and cylindrical-parabolic collectors. Plain collectors are preferred in low-temperature applications, while other collector models are preferred in high-temperature applications.
Some of the application areas of the plain collector, which is preferred at temperatures below 150 degrees, are as follows;
A solar collector is basically a flat box and consists of three main parts, a transparent cover, refrigerant carrying tubes, and an insulated backplate. The solar collector works according to the greenhouse effect principle; Solar radiation coming to the transparent surface of the solar collector is transmitted from this surface. The interior of the solar collector is usually evacuated, the energy contained in the solar collector is basically trapped, thereby heating the refrigerant inside the tubes. The tubes are usually made of copper and the backplate is painted black to help absorb solar radiation. The solar collector is usually insulated to prevent heat losses.
The main components in an active solar water heating system are:
The location of the solar collector takes into account how the region receives the sun. The solar collectors placed on the panels that will be placed to receive the sun for the longest period of time can thus operate during long sunny hours. In addition, collectors that can withstand heat up to 100 degrees and support this much heat generation are functional in this way.
Regardless of the use or type, the basic principle for solar collectors is to convert the light received from the sun into heat. This would be a more meaningful answer to the question of what is a solar collector. The liquids in the collectors are not just water, they are specially produced. Thus, problems such as freezing or calcification are prevented.
This liquid, which has a heat transport feature, does not lose heat in a short time and helps to reach the required temperature. Thus, it is possible to benefit from these systems in many different areas such as heating. Solar collectors, therefore, play a very important role in solar energy systems.
There are factors that affect the efficiency of solar collectors. High efficiency is obtained from the collectors used in solar energy applications only if the right material is selected and used. The main objective in this selection should be to produce a competitive collector with high efficiency and low cost. The efficiency of a collector is defined as the ratio of the amount of useful energy it collects to the amount of energy falling on it. In an efficient solar collector, it should be ensured that most of the incoming solar radiation is absorbed by the absorber plate, minimizing the heat loss by using thermal insulation material, and almost all of the solar energy converted into heat is transmitted to the liquid.
The most important factors affecting the collector efficiency are;