Considerations on the heat dissipation of photovoltaic panels
The current market’s discussion on energy is becoming more and more prosperous. It has become a fact that my country’s energy structure is quite unreasonable. Nearly 70% of the energy consumed every year is raw coal. The energy structure dominated by raw coal is bound to cause a large amount of carbon dioxide emissions and cause environmental pollution. Caused ecological destruction, the current situation is still intensifying.
Renewable energy represented by solar energy has attracted more and more attention. Solar energy is by far the most abundant, inexhaustible, inexhaustible and cleanest renewable energy. Among the many renewable energy use technologies, photovoltaic panel power generation technology is one of the best methods.
Only 5% to 25% of the solar radiation absorbed by photovoltaic panels is converted into electric energy, and the remaining unusable energy is converted into heat energy. The photoelectric efficiency of photovoltaic panels is affected by the surface temperature. When the surface temperature exceeds 25°C under the sunlight of 1000W/m2, the photoelectric efficiency will decrease by 0.4%-0.5% for every 1 degree increase.
Therefore, research on how to effectively reduce the heat generation of photovoltaic panels, reduce the surface temperature of photovoltaic panels, and improve the photoelectric conversion efficiency of photovoltaic panels is of great significance in dealing with the depletion of traditional fossil energy and environmental pollution.
Photovoltaic panel heat dissipation technology uses external technical means to dissipate heat when the surface temperature of the photovoltaic panel is too high, so that the surface temperature of the photovoltaic panel is maintained in a suitable temperature range, thereby improving the photoelectric conversion efficiency of the photovoltaic panel. The heat dissipation technology considers the following requirements:
1) Effectively reduce the temperature, improve the efficiency of photovoltaic panels, and have good temperature uniformity.
2) Simple structure, easy operation, low cost and convenient maintenance.
At present, there are three technologies: air heat dissipation, heat pipe heat dissipation, and material heat dissipation (composite phase change materials with improved materials).
Air cooling
Features
The heat generated on the surface of the photovoltaic panel is removed by air convection, and this technical method is simple in structure, low in cost, and easy to operate. According to whether the air convection flows automatically or artificially, it can be divided into natural convection and forced convection. Natural convection means that only the local density difference formed by the temperature difference between the air itself and the surface of the photovoltaic panel is used for flow and heat exchange. The heat on the surface of the photovoltaic panel is spontaneously transferred to the air, and an electric fan or fan can be used to force the air. Flow for heat dissipation and cooling.
Shortcoming
Although the air heat dissipation technology has the advantages of simple structure and low cost, the air thermal conductivity is low and it is easily affected by the external environment. Therefore, new heat dissipation technology is needed to solve these existing problems.
Heat pipe cooling
Features
Heat pipe heat dissipation has a better heat dissipation effect than air heat dissipation. Heat pipe heat dissipation improves additional equipment, such as pumps, heat pipes and control circuits. Photovoltaic panel/heat pipe heat dissipation technology uses heat pipe thermal conductivity and fluid medium heat dissipation, which can be A heat dissipation method that quickly absorbs the heat generated by photovoltaic panels and collects the heat for use.
Shortcoming
Although heat pipe heat dissipation technology can effectively reduce the surface temperature of photovoltaic panels, it has the disadvantages of low thermal conductivity and latent heat of general fluid media, and the complex structure of the entire heat dissipation system, difficult maintenance, and high cost.
