CN106972068A - The method for improving solar energy power generating plate photovoltaic conversion efficiency - Google Patents

Abstract

The invention provides a method for improving the photovoltaic conversion efficiency of a solar photovoltaic power generation panel, comprising: using an EVA adhesive film to bond a composite metamaterial film to the light-receiving surface of a solar photovoltaic power generation panel; the composite metamaterial film is prepared by the following method : Disperse micron-sized SiO ₂ microspheres in a dispersant and perform ultrasonic vibration to obtain a SiO ₂ microsphere dispersion; make the SiO ₂ microsphere dispersion evenly distributed on the polymethylpentene film to make the SiO ₂ microspheres The ball dispersion was volatilized to obtain a polymethylpentene film with _SiO2 microspheres; the polymethylpentene film with _SiO2 microspheres was rolled using a rolling machine to obtain a composite metamaterial film. The invention utilizes the principle of radiation cooling to significantly reduce the surface temperature of the solar photovoltaic power generation panel, thereby improving the photovoltaic conversion efficiency of the solar photovoltaic power generation panel, and also has the advantages of low energy consumption, high efficiency and simple structure.

Description

Method for Improving Photovoltaic Conversion Efficiency of Solar Photovoltaic Power Generation Panel

technical field

The invention belongs to the technical field of photovoltaic power generation and energy saving and emission reduction, and in particular relates to a method for improving the photovoltaic conversion efficiency of a solar photovoltaic power generation panel.

Background technique

Research data show that: when the battery temperature rises by 1°C, the photoelectric conversion efficiency of crystalline silicon cells decreases by about 0.4%, and that of amorphous silicon cells decreases by about 0.1%. The aging rate of crystalline silicon cells will double. At this stage, by comprehensively considering factors such as battery temperature, temperature uniformity, reliability, and simplicity, photovoltaic power generation mainly adopts passive and active cooling methods, and there are mainly the following specific cooling applications:

(1) Air cooling: Air cooling is divided into natural convection cooling and forced convection cooling. At present, natural convection cooling mainly focuses on improving the surface convective heat transfer coefficient and increasing the heat transfer area, but this method has a certain heat dissipation limit. In forced convection cooling, fans need to be connected to improve the surface convective heat transfer coefficient, but at this time, it is necessary to comprehensively consider the balance between the improvement of battery efficiency and the increase of fan power consumption. In 2012, H.G.Teo et al. designed an active cooling system for solar cell modules. The system includes a DC fan and an AC fan. The DC fan supplies air to the air duct at the back of the battery pack, and the AC fan controls the velocity and flow of the air delivered to the duct. Figure 1 is a schematic structural diagram of a traditional solar air cooling system.

(2) Liquid cooling: Liquid cooling can be divided into heat exchanger cooling, surface cooling and liquid immersion cooling according to the working fluid flow mode and placement location. Heat exchanger cooling mainly refers to the heat dissipation method in which the cooling medium does not directly contact the photovoltaic panel, but transfers heat to the external environment through the cooling medium that circulates continuously inside the water-cooled heat exchanger. Surface cooling refers to spraying the cooling medium on the surface of the photovoltaic panel by spraying or other equipment, or directly contacting the surface of the photovoltaic panel with the cooling medium, and using the convection heat transfer formed between the cooling medium and the photovoltaic panel to take away the heat on the surface of the photovoltaic panel. Way. This method further develops the method of jet impingement and microchannel hybrid cooling. Liquid immersion cooling refers to the cooling method that immerses the battery in a static or circulating cooling medium so that the cooling medium is in direct contact with the battery, and uses the characteristics that both sides of the battery can be used as effective heat dissipation surfaces to exchange heat efficiently with the cooling medium .

(3) Evaporative cooling: This method takes away part of the heat through the phase change of the cooling medium in direct contact with the photovoltaic power generation panel.

(4) Thermoelectric cooling: Thermoelectric cooling is based on the temperature drop generated by the Peltier effect to reduce the temperature of heating components. If the temperature control circuit is used for control, the temperature control can be accurate to 0.1 °C, and it has no noise and reliability during operation. higher sex characteristics.

Some of the above methods are currently used, but there are some problems: the structure of the air cooling system is relatively simple, the cost is low, and the operation is convenient. However, the heat transfer coefficient of air is low, and the cooling effect is limited, especially in low-latitude regions, and when the ambient temperature is high, the cooling effect is poor; liquid cooling is also restricted by climatic conditions, in cold areas in the north and areas lacking water It cannot be applied on a large scale; although the effect of thermoelectric cooling is obvious, its extra power consumption is large and the economy is not high.

Contents of the invention

The purpose of the present invention is to provide a method for improving the photovoltaic conversion efficiency of a solar photovoltaic power generation panel by utilizing radiation refrigeration.

In order to achieve the above object, the present invention provides a method for improving the photovoltaic conversion efficiency of a solar photovoltaic power generation panel, comprising: using an EVA adhesive film to bond the composite metamaterial thin film to the light-receiving surface of a solar photovoltaic power generation panel; the composite metamaterial The film was prepared as follows:

Disperse micron-sized SiO ₂ microspheres in a dispersant and perform ultrasonic oscillation to obtain a SiO ₂ microsphere dispersion;

Make the SiO microsphere dispersion evenly distributed _on the polymethylpentene film, make the SiO microsphere dispersion volatilize, and obtain the polymethylpentene film distributed with the _SiO microsphere _;

A rolling machine was used to roll the polymethylpentene film distributed with _SiO2 microspheres to obtain a composite metamaterial film.

Preferably, the aluminum alloy frame is used to fix the part of the composite metamaterial thin film beyond the light-receiving surface of the photovoltaic generation panel on the four sides of the photovoltaic generation panel, so that the bonding between the composite metamaterial thin film and the photovoltaic generation panel is more reliable.

Preferably, the particle size of the SiO ₂ microspheres is 7um-9um.

Preferably, in the composite metamaterial thin film, the volume ratio of SiO ₂ microspheres is 5%-7%.

Preferably, the composite metamaterial thin film has a thickness of 1 um to 100 um.

Further, the dispersant is absolute ethanol

The present invention also provides a solar photovoltaic power generation panel that can improve photovoltaic conversion efficiency. The light-receiving surface of the solar photovoltaic power generation panel is sequentially laid with EVA adhesive film and composite metamaterial film. The composite metamaterial film is as follows Method preparation:

Disperse micron-sized SiO ₂ microspheres in a dispersant and perform ultrasonic oscillation to obtain a SiO ₂ microsphere dispersion;

Make the SiO microsphere dispersion evenly distributed _on the polymethylpentene film, make the SiO microsphere dispersion volatilize, and obtain the polymethylpentene film distributed with the _SiO microsphere _;

Composite metamaterial films obtained by rolling polymethylpentene films distributed with _SiO2 microspheres using a rolling mill

The present invention further provides a method for preparing a composite metamaterial thin film, comprising the steps of:

Disperse micron-sized SiO ₂ microspheres in a dispersant and perform ultrasonic oscillation to obtain a SiO ₂ microsphere dispersion;

Make the SiO microsphere dispersion evenly distributed _on the polymethylpentene film, make the SiO microsphere dispersion volatilize, and obtain the polymethylpentene film distributed with the _SiO microsphere _;

Composite metamaterial films obtained by rolling polymethylpentene films distributed with _SiO2 microspheres using a rolling mill

The invention utilizes the principle of radiative cooling to radiate the surface heat of the solar photovoltaic power generation panel to outer space through an atmospheric window, thereby reducing the surface temperature of the solar photovoltaic power generation panel, and further improving the photovoltaic conversion efficiency of the solar photovoltaic power generation panel. The invention utilizes a composite metamaterial thin film, which is formed by random distribution and polymerization of TPX (polymethylpentene) with good sunlight transmittance and polar dielectric _SiO2 microspheres of special size. The composite metamaterial film can realize radiative cooling and has high cooling power. The composite metamaterial film is covered on the solar silicon photovoltaic cell, and the temperature of the cell is reduced by using the layer to exchange heat with the radiation of space. The composite metamaterial film is almost completely transparent to incident sunlight, but has a very high emissivity to its own thermal radiation, so it can cool down the solar panel without affecting the incident efficiency of solar energy. In addition, it also has the advantages of adopting passive radiation cooling, no additional power consumption, mature manufacturing process, low cost, and convenient application, which is conducive to large-scale popularization and application.

The composite metamaterial thin film adopted in the present invention can be nearly completely transparent to the solar spectrum; at the same time, it has a high infrared emissivity under the atmospheric window, that is, sunlight can pass through the material without heating it, and the material can simultaneously Infrared light that meets the conditions (wavelength within the atmospheric window range) is directly radiated into space to reduce its own temperature. The present invention creatively lays the material on the surface of the solar photovoltaic power generation panel, which has two functions: on the one hand, sunlight can pass through the material and irradiate the solar photovoltaic power generation panel with almost no loss, ensuring normal photovoltaic power generation. Power generation; on the other hand, the heat of the photovoltaic power generation panel itself will use the material to radiate into outer space in the form of infrared radiation, thereby reducing the surface temperature of the power generation panel. According to the influence of temperature on the output characteristics of photovoltaic power generation panels, it can be seen that the decrease of the temperature of the power generation panels will cause a small decrease in short-circuit current, a substantial increase in open-circuit voltage, an increase in fill factor, and a significant increase in photoelectric conversion efficiency. Compared with the traditional solar photovoltaic array cooling system, this invention innovates the mechanism of strengthening the heat transfer of photovoltaic power generation panels, changing the convective heat transfer to radiation heat transfer as the main and convective heat transfer as the auxiliary, the cooling power is considerable, and the temperature can be lowered. The effect is remarkable; at the same time, due to the passive nature of radiation heat exchange, the extra power consumption of traditional cooling methods (especially water cooling) is greatly saved, and the economy is improved; the production process of this material is simple, mass production has been achieved, non-toxic and pollution-free, Therefore, it will not impose a load on the environment while having a cost advantage.

Compared with the traditional solar photovoltaic array cooling method, the advantages of the present invention are:

(1) Radiation is the heat dissipation mechanism supplemented by convective heat transfer. Under the action of this mechanism, on the one hand, a cooling power of about 200W/m2 can be obtained at noon, and the cooling effect is remarkable; on the other hand, due to the passive nature of radiation cooling, no special cooling medium is required, and no external power source is required to drive, so a lot of extra power consumption is saved. , The efficiency and economy of the entire solar power generation system are significantly improved.

(2) Film-like composite metamaterials. On the one hand, it is easy to process and manufacture; on the other hand, it is easy to be attached to the surface of the solar power generation panel. cost and improve system reliability.

(3) The production process is simple, the manufacturing cost is low, the raw materials are environmentally friendly and non-toxic, the mechanical and chemical properties are excellent, and it is suitable for outdoor and durable use.

Description of drawings

Fig. 1 is the structural representation of traditional solar energy air cooling system;

Fig. 2 is a schematic diagram of the specific structure and working principle of the present invention.

In the figure, 1- _SiO2 microspheres, 2-polymethylpentene parent material.

detailed description

The technical solutions and technical effects of the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

See Figure 2. In this specific implementation, a composite metamaterial film is laid on the light-receiving surface of the solar photovoltaic power generation panel, and an EVA film is also provided between the light-receiving surface of the photovoltaic power generation panel and the composite metamaterial film. Adhesive bonding of film and light-receiving surface of photovoltaic power generation panel. EVA film is a thermosetting film with strong adhesion, good stability and superior optical properties. In order to make the bonding between the composite metamaterial film and the photovoltaic power generation panel more reliable, the part of the composite metamaterial film that exceeds the light-receiving surface of the photovoltaic power generation panel is fixed on the four sides of the photovoltaic power generation panel with an aluminum alloy frame.

The composite metamaterial film consists of micron-sized _SiO2 microspheres randomly distributed on a polymethylpentene (TPX) matrix material. In the composite metamaterial thin film, the randomly distributed optical material SiO ₂ microspheres are mixed with the polymer TPX because the micron-scale random optical material has high-order The electromagnetic oscillatory effect, which increases both the extinction and the optical path length of the composite metamaterial when excited, leads to near-perfect resonant absorption for self-radiation amplification. The use of TPX and _SiO2 is because both have good solar light transmittance, and the absorption is almost non-existent, so the composite metamaterial thin film will hardly cause its own temperature to rise due to the absorption of sunlight.

As a preference, the particle size of _SiO2 microspheres is selected as 7um～9um, and _SiO2 microspheres in this particle size range are more likely to be excited to produce high-order Electromagnetic oscillations to maximize the extinction coefficient and achieve uniform high emissivity through the atmospheric window. In addition, in order to obtain a better radiative cooling effect and consider the operability of material preparation, the volume ratio of SiO ₂ microspheres in the composite metamaterial film is 5% to 7%, and the thickness of the composite metamaterial film is 1um to 100um.

The preparation process of the composite metamaterial thin film is as follows:

(1) Disperse micron-sized SiO ₂ microspheres in a dispersant and perform ultrasonic oscillation to obtain a SiO ₂ microsphere dispersion. In this specific implementation, the dispersant is absolute ethanol, but not limited to absolute ethanol. The dispersant used is used to disperse SiO ₂ microspheres, and is required to be volatile, and can be separated from the TPX film through natural evaporation or forced heat exchange; moreover, it cannot chemically react with SiO ₂ and TPX.

(2) Make the SiO ₂ microsphere dispersion evenly distributed on the TPX film, and make the SiO ₂ microsphere dispersion naturally volatilize. At this time, the SiO ₂ microsphere can be evenly distributed on the TPX film. Wherein, the thickness of the TPX film is 1um-100um.

(3) Utilize rolling machine under the protection of stainless steel sheet, step ( ₂ ) gained is distributed with SiO TPX thin film of microsphere is rolled, makes SiO Microsphere is embedded _on TPX thin film closely, thus obtains the present invention composite metamaterial films.

Compared with the traditional solar photovoltaic array cooling system, the invention has simple operation and simple structure. Photovoltaic panels coated with composite metamaterial thin films can work directly under sunlight. Sunlight with a wavelength of 0.2um to 3um irradiates the composite metamaterial thin film. Due to the high transmittance of the composite metamaterial thin film, the sunlight passes through the composite metamaterial thin film and irradiates to the light-receiving surface of the photovoltaic power generation panel with almost no loss. Part of the sunlight is reflected by the light-receiving surface of the photovoltaic power generation panel and leaves through the composite metamaterial film, part of the sunlight is absorbed by the semiconductor cells of the photovoltaic power generation panel and converted into heat, and the rest of the sunlight is converted into electrical energy through the photoelectric effect. The converted part of the heat increases the temperature of the photovoltaic power generation panel, and the self-heat radiation of the photovoltaic power generation panel increases accordingly. Under the effect of the high infrared emissivity of the composite metamaterial film in the 8um-13um band, most of it can directly radiate to the 3K cosmic background, and the temperature of the photovoltaic power generation panel can be reduced.

It has been verified by experiments and simulations that the solar light transmittance of the composite metamaterial film is over 98%. The principle of electromagnetic resonance, its average infrared emissivity is greater than 0.93 in the wavelength range of 8um ~ 13um, its radiation energy density is 890W/m ² , the ambient temperature is 20°C, and it can work at a wind speed of 3m/s ~ 4m/s. A photovoltaic power generation panel with a surface temperature of 48°C produces a temperature drop of about 10°C, and can increase the photovoltaic conversion efficiency of the solar panel by 3.5% to 4.4%.

Claims (8)

1. a kind of method for improving solar energy power generating plate photovoltaic conversion efficiency, it is characterized in that：

Compound meta-material thin film is adhered to the photovoltaic power generation plate smooth surface of solar energy using EVA adhesive film；

Described compound meta-material thin film is adopted to be prepared with the following method：

By micron-sized SiO₂Microballoon disperses in dispersant, and carries out sonic oscillation, obtains SiO₂Microballoon dispersion liquid；

Make SiO₂Microballoon homogeneous dispersion is distributed on poly-methyl pentene film, makes SiO₂Microballoon dispersion liquid volatilizees, and is distributed with SiO₂The poly-methyl pentene film of microballoon；

Using roll mill to SiO is distributed with₂The poly-methyl pentene film of microballoon is rolled, and obtains compound meta-material thin film.

2. the method for solar energy power generating plate photovoltaic conversion efficiency is improved as claimed in claim 1, it is characterized in that：

Compound meta-material thin film is fixed on photovoltaic power generation plate four beyond the part of photovoltaic power generation plate smooth surface using aluminum alloy frame Side.

3. the method for solar energy power generating plate photovoltaic conversion efficiency is improved as claimed in claim 1, it is characterized in that：

Described SiO₂The particle diameter of microballoon is 7um~9um.

4. the method for solar energy power generating plate photovoltaic conversion efficiency is improved as claimed in claim 1, it is characterized in that：

In described compound meta-material thin film, SiO₂The volume accounting of microballoon is 5%~7%.

5. the method for solar energy power generating plate photovoltaic conversion efficiency is improved as claimed in claim 1, it is characterized in that：

Described compound meta-material thin film thickness is 1um~100um.

6. the method for solar energy power generating plate photovoltaic conversion efficiency is improved as claimed in claim 1, it is characterized in that：

Described dispersant is absolute ethyl alcohol.

7. a kind of solar energy power generating plate for improving photovoltaic conversion efficiency, it is characterized in that：

EVA adhesive film, compound meta-material thin film are laid with the smooth surface of described solar energy power generating plate successively, described answers Conjunction meta-material thin film is adopted to be prepared with the following method：

By micron-sized SiO₂Microballoon disperses in dispersant, and carries out sonic oscillation, obtains SiO₂Microballoon dispersion liquid；

Make SiO₂Microballoon homogeneous dispersion is distributed on poly-methyl pentene film, makes SiO₂Microballoon dispersion liquid volatilizees, and is distributed with SiO₂The poly-methyl pentene film of microballoon；

Using roll mill to SiO is distributed with₂The poly-methyl pentene film of microballoon is rolled, and obtains compound meta-material thin film.

8. a kind of preparation method of compound meta-material thin film, it is characterized in that, including step：

By micron-sized SiO₂Microballoon disperses in dispersant, and carries out sonic oscillation, obtains SiO₂Microballoon dispersion liquid；

Make SiO₂Microballoon homogeneous dispersion is distributed on poly-methyl pentene film, makes SiO₂Microballoon dispersion liquid volatilizees, and is distributed with SiO₂The poly-methyl pentene film of microballoon；

Using roll mill to SiO is distributed with₂The poly-methyl pentene film of microballoon is rolled, and obtains compound meta-material thin film.