Efficient cleaning agent and cleaning method for aluminum oxide factory photovoltaic power generation panel

Abstract

The invention provides an efficient cleaning agent for a photovoltaic power generation panel in an aluminum oxide factory and a cleaning method, belongs to the technical field of new energy cleaning, and aims to solve the problems that an existing cleaning agent cannot effectively remove alkaline composite pollutants in the aluminum oxide factory and is short of long-acting protection. The cleaning agent comprises 0.15%-0.25% of oxalic acid, 1.5%-2.5% of citric acid and 1.5%-2.5% of nano fluorine coating liquid, the pH value is 4.0-4.5, alkaline sodium salt is neutralized through the oxalic acid, metal oxides such as Fe2O3 / CaO are chelated through the citric acid, a hydrophobic protection layer is formed through the nano fluorine coating liquid, and the synchronous pollution removal and self-cleaning functions are achieved. The cleaning agent provided by the invention can remove alkaline residues, metal oxides and hard scale at one time, and a reaction product is water-soluble and easy to wash away; a hydrophobic membrane with a contact angle of more than 110 degrees is formed, and the later dust adhesion rate is reduced; corrosion of an EVA adhesive film and a battery piece is avoided in a weak acid environment, the recovery rate of single-time cleaning output power is increased to 24-30%, and the service life of the assembly is prolonged.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of new energy clean technology, and particularly relates to a high-efficiency cleaning agent for photovoltaic panels in an alumina plant and a cleaning method. BACKGROUND

[0002] Photovoltaic power generation technology is based on the photovoltaic effect of semiconductor PN junction, which excites electron-hole pairs by absorbing photons and forms electric current under the action of built-in electric field. After the installation mode, installation angle and model of the photovoltaic panel are determined, dust adhesion and shadow blocking become the key factors affecting the power generation efficiency in operation, which can cause the power generation capacity to decrease by 5%-30% and induce hot spot effect, with the local temperature as high as 130℃, and even cause permanent damage to the components. This problem is particularly prominent in industrial pollution areas, such as alumina production plant, the dust dispersed in the air of which mainly comes from the processing link of bauxite, and the composition is complex and has strong corrosiveness.

[0003] The dust in the alumina plant is mainly composed of sodium-containing alkaline substances (NaOH, NaHCO3, NaAlO2) and metal oxides (Fe2O3, CaO, etc.). These pollutants form a composite deposit on the surface of the photovoltaic panel: the alkaline substances react with silicates to form hard scale (such as calcium magnesium silicate), which is difficult to remove by conventional physical cleaning; sodium salt continuously corrodes the glass surface layer to form soluble sodium silicate, causing surface etching pits and damaging the optical flatness; unevenly attached alkaline residues not only directly block the light incidence, but also form resistance differences due to local area blocking, causing hot spot effect, leading to abnormal temperature rise of the components, and even burning the battery piece; long-term alkaline corrosion can damage the sealing property of the encapsulating material (such as EVA film) of the photovoltaic component, accelerate the oxidation of the internal circuit and the aging of the battery piece, and shorten the service life of the component.

[0004] Current commercially available cleaning agents are mainly designed for ordinary dust or calcium and magnesium scale, and have no way to deal with the alkaline composite pollution specific to the alumina plant. Although existing patent technologies attempt to improve the cleaning scheme, for example, patent TWI768791B uses a cleaning agent containing weak acid, antistatic agent and chelating agent to realize dust removal of solar cell panel in ordinary dust environment, patent CN106190617A uses fluoride to remove calcium scale, patent CN107904047A improves the cleaning ability of general metal / plastic scale by compounding 5 kinds of acid, and patent US20100267192A1 uses a single component organic acid to remove metal pollutants. However, the above technologies still have limitations: first, they cannot simultaneously neutralize alkaline sodium salt, dissolve metal oxides and remove secondary deposits; second, the complex formula of the acidic cleaning agent increases the cost and operation difficulty; third, there is a lack of surface protection mechanism, and the pollutants quickly reaccumulate after cleaning. Therefore, it is urgent to develop a special cleaning agent that is specific to the characteristics of the alumina environment and has the functions of high-efficiency cleaning and long-term protection. SUMMARY

[0005] In order to solve the above problems in the prior art, the application provides a high-efficiency cleaning agent specially used for an alumina production area photovoltaic panel, which comprises the following components in mass percentage: 0.15-0.25% oxalic acid, 1.5-2.5% citric acid, 1.5-2.5% nano-fluorine plating solution, and the rest is deionized water; and the pH value of the cleaning agent is 4.0-4.5.

[0006] Preferably, the pH value of the cleaning agent is adjusted by adding sodium bicarbonate into the cleaning agent.

[0007] Preferably, the total content of the effective components, i.e., oxalic acid, citric acid and nano-fluorine plating solution, in the cleaning agent is 3.5-4.8%.

[0008] Preferably, the nano-fluorine plating solution comprises polytetrafluoroethylene.

[0009] The application further provides a method for cleaning an alumina production area photovoltaic panel, which comprises the following steps:

[0010] Firstly, a cleaning agent solution is prepared, which comprises the following components in mass percentage: 0.15-0.25% oxalic acid, 1.5-2.5% citric acid, 1.5-2.5% nano-fluorine plating solution mainly comprising polytetrafluoroethylene, and the rest is deionized water; and the pH value of the cleaning agent is adjusted to 4.0-4.5 by adding sodium bicarbonate.

[0011] Then, surface spraying is performed, i.e., the cleaning agent solution prepared in step (1) is uniformly applied to the surface of the photovoltaic panel to be cleaned by using a spraying type or brush roller type cleaning device, and during the application process, the spraying pressure is controlled in the range of 0.20-0.30 MPa to ensure that the cleaning agent effectively covers the surface of the photovoltaic panel.

[0012] Subsequently, reaction and standing are performed, i.e., after the cleaning agent completely covers the surface of the photovoltaic panel, standing is performed for 5-8 minutes to make the cleaning agent fully react with the dirt on the panel surface and play the roles of acid dissolution and nano-fluorine plating solution.

[0013] Finally, rinsing and air drying are performed, i.e., the surface of the photovoltaic panel is rinsed with deionized water with a pressure not exceeding 5 MPa, and during the rinsing process, continuous rinsing is performed until no foam or residual cleaning agent or dirt is observed on the surface of the photovoltaic panel, so as to ensure that the cleaning agent is completely removed, and after the rinsing is completed, the photovoltaic panel is naturally air dried or auxiliary drying is performed.

[0014] Preferably, the rinsing operation is continued until the pH value of the rinsing waste liquid flowing or draining from the surface of the photovoltaic panel reaches 6-7, so as to serve as one of the criteria for judging whether the rinsing is complete and the surface is close to neutral.

[0015] The present application can realize the removal of alkali dust, removal of iron oxide / calcium and deposition of self-cleaning film at one time. Through the synergistic reaction of oxalic acid and citric acid, the alkali dust, iron oxide and calcium magnesium silicate scale unique to the photovoltaic panel in the alumina plant are completely removed, and the pain point that the existing cleaning agent cannot handle the alkaline residue is solved. The reaction products such as sodium oxalate, ferric citrate and aluminum citrate are all water-soluble substances, and there is no secondary deposition after rinsing. The nano coating solution forms an ultra-thin hydrophobic protective film on the surface of the photovoltaic panel, the surface contact angle is > 110°, the adhesion of the alkaline pollutants in the later stage is significantly reduced, and long-term protection is realized. The pH value is controlled at 4.0-4.5, which can not only avoid the corrosion of acid to EVA film and battery pieces, but also ensure the cleaning effect. Single cleaning can greatly improve the output power recovery rate and prolong the service life of the photovoltaic module. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be clearly and completely described below in combination with specific embodiments of the present application.

[0017] The cleaning agent of embodiments 1-2 of the present application is a high-efficiency cleaning agent specially used for photovoltaic panels in the alumina production area, and the core components thereof include oxalic acid (H2C2O4), citric acid (H3C6H5O7) and nano fluorine coating solution.

[0018] Oxalic acid mainly performs neutralization reaction on sodium-containing alkali dust (such as NaOH, NaHCO3 and NaAlO2) to generate soluble sodium oxalate and carbon dioxide gas, and also generates aluminum hydroxide precipitate and slightly soluble calcium oxalate, which specifically includes the following reaction formulae:

[0019] H2C2O4+ NaHCO3→ Na2C2O4+ 2CO2↑+ H2O

[0020] H2C2O4+ NaAlO2→ Na2C2O4+ Al(OH)3↓

[0021] H2C2O4+ CaO→ CaC2O4+ H2O

[0022] Citric acid is responsible for dissolving the above-mentioned secondary precipitates and residual iron oxide and calcium oxide pollutants: it reacts with aluminum hydroxide to generate soluble aluminum citrate, reacts with calcium oxalate to generate soluble calcium citrate complex, and reacts with iron oxide to generate ferric citrate, which specifically includes the following reaction formulae:

[0023] 3H3C6H5O7+ Al(OH)3→ Al(C6H5O7)3+ 3H2O

[0024] 3H3C6H5O7 + CaC2O4 → Ca(H2C6H5O7)3 + H2C2O4

[0025] H3C6H5O7 + Fe2O3 → Fe(C6H5O7)3 + 3H2O

[0026] The nano-fluorine coating solution forms a protective layer after cleaning, reduces the surface energy to make rainwater and oil dirt roll off quickly, and improves the hardness of the glass surface to reduce subsequent pollution adhesion.

[0027] Example 1

[0028] Dissolve oxalic acid 2 g and citric acid 20 g in 958 g of deionized water, and magnetically stir for 10 min until completely dissolved; then slowly add nano-fluorine coating solution 20 g, continue to stir for 15 min to form a uniform mixture. Titrate with 5% (mass fraction) sodium bicarbonate solution, and adjust the pH of the system to 4.3 to obtain the cleaner. The mass fraction of each effective component is as follows: oxalic acid 0.20%, citric acid 2.00%, and nano-fluorine coating solution 2.00%.

[0029] Example 2

[0030] Dissolve oxalic acid 1.5 g and citric acid 15 g in 968.5 g of deionized water, then add nano-fluorine coating solution 15 g, and adjust the pH to 4.5 with 5 wt% sodium bicarbonate solution to prepare the cleaner. The mass fraction of each effective component is as follows: oxalic acid 0.15%, citric acid 1.50%, and nano-fluorine coating solution 1.50%.

[0031] Example 3

[0032] Dissolve oxalic acid 2.5 g and citric acid 25 g in 966 g of deionized water, then add nano-fluorine coating solution 25 g, and adjust the pH to 4.0 to prepare the cleaner. The mass fraction of each effective component is as follows: oxalic acid 0.25%, citric acid 2.50%, and nano-fluorine coating solution 2.50%.

[0033] Comparative Example 1

[0034] Only use deionized water 1000 g as the cleaning solution, and other conditions are the same as in Example 1.

[0035] Comparative Example 2

[0036] Prepare a dilute solution containing 0.2% oxalic acid and 2.00% citric acid by mass, without nano-fluorine coating solution, and other conditions are the same as in Example 1.

[0037] Comparative Example 3

[0038] Select commercially available A multifunctional full-effect cleaner for photovoltaic glass, model QCP0091S, was prepared according to the concentration of 1000 g in the instruction manual, and other conditions were the same as those in Example 1.

[0039] The monocrystalline silicon photovoltaic panels in Examples 1 to 3 and Comparative Examples 1 to 3 were first exposed to the air in the alumina factory for 60 days, so that the surface of the panels was deposited with a sodium-containing alkaline dust (Na + about 3.1%). Then, the cleaner in Examples 1 to 3 and Comparative Examples 1 to 3 was applied to the surface of the monocrystalline silicon photovoltaic panel to be cleaned by using a spray-roller integrated cleaning robot, the spray pressure was 0.25 MPa, and after the cleaner completely covered the surface of the photovoltaic panel, it was left to stand for 5 to 8 minutes, so that the oxalic acid was fully neutralized with the alkaline substance, and at the same time, the citric acid dissolved the metal oxides and the pre-deposits; then, the surface of the photovoltaic panel was rinsed with deionized water until there was no foam and residue, and was naturally air-dried. After cleaning, the nano-fluorine coating solution automatically formed a hydrophobic hardening film on the surface of the glass, without the need for additional operations.

[0040] The performance of the cleaner after cleaning the photovoltaic panel glass was evaluated, and the detection indexes included: light transmittance, transmittance reduction, surface static contact angle, hydrophobic film morphology, and output power recovery rate (25℃, 1000W·m - 2, AM1.5).

[0041] 1. Transmittance test

[0042] The cleaner in Examples 1 to 3 and Comparative Examples 1 to 3 was coated on the surface of the photovoltaic panel glass, and after drying, the transmittance was measured by using a UV-Vis spectrometer with a halogen lamp light source (λ = 550 nm) through direct contact method.

[0043] 2. Transmittance reduction test

[0044] The initial transmittance of the glass sample after the cleaning performance test was tested, and after being used in the solar panel for 3 months, the transmittance was measured again.

[0045] 3. Surface static contact angle test

[0046] The OCA optical contact angle instrument was used to measure the surface contact angle of the photovoltaic panel glass after cleaning and drying.

[0047] 4. Hydrophobic film morphology analysis

[0048] The high-resolution transmission electron microscope (HR-TEM) was used to observe the surface morphology of the test sample in Example 1 before and after soaking, and to measure the thickness of the hydrophobic film formed by the cleaner.

[0049] 5. Output power recovery rate test

[0050] Standard-sized photovoltaic modules were collected after 90 days of exposure to pollution in an alumina plant area. A solar simulator (IEC 60904-9 standard) was used to test these modules at a constant temperature of 25.0±0.5℃ and an irradiance of 1000±10 W·m. - Under AM1.5 spectral conditions, the maximum output power P in the polluted state was determined using an IV curve analyzer. 污染 After cleaning with the cleaning agents of Examples 1 to 3 and Comparative Examples 1 to 3 respectively, the products were rinsed with deionized water, dried with nitrogen, and left to stand for 2 hours. The power P after cleaning was measured under the same equipment and test conditions. 清洁 The power recovery rate is calculated using the following formula:

[0051] Power recovery rate = (P 清洁 -P 污染 )×P 污染

[0052] Table 1

[0053]

[0054]

[0055] The results showed that the light transmittance of the cleaning agents in Examples 1 to 3 exceeded 99.0% after being applied to the photovoltaic panels, and the light transmittance decreased by less than 2.0% after 3 months of normal use of the photovoltaic panels. This indicates that the cleaning agents have excellent cleaning performance and anti-fouling properties, can significantly reduce alkaline dust residue, improve light transmittance and surface hydrophobicity, and increase the output power recovery rate to 24-30%, which is much higher than that of the comparative example. This verifies the excellent cleaning-coating integrated effect of the ternary synergistic formulation.

[0056] The above description is a preferred embodiment of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A high efficiency cleaner for photovoltaic panels in an alumina plant, characterized in that, The cleaning agent comprises the following components by mass percentage: oxalic acid content of 0.15% to 0.25%, citric acid content of 1.5% to 2.5%, nano-fluorine coating solution content of 1.5% to 2.5%, and the rest is deionized water; the pH value of the cleaning agent is 4.0 to 4.

5.

2. The cleaning agent of claim 1, wherein, The pH value of the cleaning agent is adjusted by adding sodium bicarbonate to the cleaning agent.

3. The cleaning agent of claim 1, wherein, The total content of oxalic acid, citric acid and nano-fluorine coating solution in the cleaning agent is 3.5% to 4.8%.

4. The cleaning agent of claim 1, wherein, The component of the nano-fluorine coating solution comprises polytetrafluoroethylene.

5. A method of cleaning photovoltaic panels at an alumina plant, characterised by, The method comprises the following steps: (1) solution preparation: preparing the cleaning agent according to any one of claims 1 to 4; (2) surface spraying: uniformly applying the cleaning agent to the surface of the photovoltaic panel to be cleaned through a spraying or brush roller cleaning device, and the spraying pressure is 0.20 to 0.30 MPa; (3) reaction standing: standing for 5 to 8 minutes after the cleaning agent completely covers the surface of the photovoltaic panel; (4) rinsing and air-drying: rinsing the photovoltaic panel with deionized water with a pressure of not more than 5 MPa until there is no foam and residue on the surface, and then naturally air-drying or auxiliary drying the photovoltaic panel after rinsing.

6. The method of claim 5, wherein, In the step (4), the photovoltaic panel is rinsed with deionized water until the pH value of the rinsing waste liquid flowing or discharged from the surface of the photovoltaic panel is 6 to 7.

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