At present, water cleaning is still one of the important ways to clean photovoltaic modules, and the dust accumulation and residual water droplets on the surface of photovoltaic modules will have a certain degree of impact on the output power of photovoltaic modules, so determine the reasonable water used for cleaning photovoltaic modules It is of great significance to measure the amount of water and explore the impact of residual water on photovoltaic modules. Two kinds of water cleaning experiments with different initial attachments of photovoltaic modules were designed. By observing the experimental phenomena and analyzing the output power of photovoltaic modules obtained by different water sprinkling amounts, the results showed that: due to the enhanced adsorption of sand particles and the increased resistance, photovoltaic modules with wet surfaces Compared with photovoltaic modules with dry surface, it is easier to deposit sand and other shelters; rainwater has a blocking effect on photovoltaic modules and will accelerate the deposition of dust on the surface of photovoltaic modules, which in turn affects the output power of photovoltaic modules; the stage of substantial growth in the output power of photovoltaic modules The corresponding amount of water is the reasonable amount of water required for the photovoltaic module to achieve the purpose of cleaning, and the residual water droplets should be wiped off after cleaning.


As a new energy technology, photovoltaic power generation has broad development prospects. It can be seen from the scale of the photovoltaic industry that China's photovoltaic industry has developed rapidly in recent years: from 2010 to 2020, China's photovoltaic module production capacity increased from 20 GW to 192.7 GW, with a compound annual growth rate of 25.4%. However, the cleaning technology of photovoltaic modules is not yet mature, and it is difficult to meet the requirements of improving cleaning efficiency and reducing cleaning costs at the same time. Therefore, it is necessary to formulate a reasonable cleaning plan to further increase the output power of photovoltaic modules. Therefore, it is of great significance to study the impact of cleaning water consumption and water residue on photovoltaic modules.


The surface cleanliness of photovoltaic modules has an important impact on its output power. Therefore, the cleaning frequency in areas with relatively humid environment is generally once every 3 to 5 months, and the cleaning frequency in areas with relatively dry environments is generally once a month. Accordingly, the cleaning market for photovoltaic modules is broad, and realizing low-cost and high-efficiency operation of cleaning devices has important economic value.
According to the literature search, the existing cleaning methods for photovoltaic modules mainly include:
1) Natural dust removal method. This method is to use natural rainfall and wind to clean photovoltaic modules naturally, but it is only applicable to southern China where the annual precipitation is 800-1000 mm, and has strong geographical limitations.
2) Manual cleaning method. This method is currently the main cleaning method used by many photovoltaic power plants in China [2]. It uses water guns, rolling brushes, and cleaning cloths to clean photovoltaic modules [3]. The operation is simple, but manual cleaning is labor-intensive and the high-pressure water guns Impact force can also cause damage to PV modules.
3) Vehicle-mounted mobile washing machine. Xu Qiaonian and others believe that the use of vehicle-mounted mobile cleaning machines is suitable for natural environments with a lot of sand and dust and far away from water sources. It is convenient to use and conducive to saving water, and has high cleaning efficiency. However, vehicle-mounted component cleaning vehicles are bulky and expensive, and can only be used in large-scale plain ground photovoltaic power stations, and cannot be widely used. Moreover, mechanical cleaning devices have problems such as high comprehensive power consumption and low intelligence.
4) Dust removal without water. Wang Jiwei et al. found that electric curtain dust removal technology has been successfully applied to photovoltaic modules in the aerospace field. This technology realizes anhydrous cleaning and high cleaning efficiency, but the cost of this technology is relatively high, and it is only suitable for small-area photovoltaic modules, and it is not suitable for large-scale photovoltaic power plants at present. Wang Zhe and others studied an automatic device for anhydrous cleaning of photovoltaic modules by using Bernoulli's "boundary layer surface effect" and the principle of a vacuum cleaner. Jiang Zhenhai and others optimized the design of the water-free dust removal device for photovoltaic modules, verified the stiffness and strength of the upper limit system by using the finite element simulation method, carried out a lightweight design for the transmission shaft, and carried out dust removal tests at the same time, and designed the dust removal rate when the highest Operating parameters of the device. Li Feng designed a dry-type dust-removing photovoltaic module cleaning robot, which relies on vacuum negative pressure to quickly complete the cleaning work without water and detergent. Efficiency and reliability all need to be studied for further improvement.

Water accumulation and cleaning effect will have a direct impact on the output power of photovoltaic modules. Due to the complex composition of ash accumulation, when the ash deposition process encounters water vapor in the air or is affected by precipitation, acid and alkali will be generated on the surface of photovoltaic modules. The reaction corrodes the photovoltaic glass cover, causing diffuse reflection of sunlight; if water droplets gather on the surface of the photovoltaic module after precipitation, it will cause light refraction and reflection, and destroy the uniformity of light transmission in the glass cover. These effects will reduce the absorption of solar radiation by photovoltaic modules and reduce their output power.

Dust removal with water is still an important method for cleaning photovoltaic modules at present, but both water accumulation and cleaning effect will have a direct impact on the output power of photovoltaic modules. Based on this, from the perspective of water conservation and efficient cleaning, this paper considers the differences in the types of dust accumulation on photovoltaic modules in different regions, and designs two kinds of water cleaning experiments with different initial attachments of photovoltaic modules. Based on the output power of photovoltaic modules, determine the reasonable amount of water needed to clean photovoltaic modules, and explore the impact of residual water on photovoltaic modules.

In this paper, by designing two kinds of water cleaning experiments with different initial attachments of photovoltaic modules, the problems related to water cleaning of photovoltaic modules are studied, and the following conclusions are drawn:

1) Compared with photovoltaic modules with dry surfaces, photovoltaic modules with wet surfaces are more likely to deposit sand and other shelters due to the enhanced sand adsorption and increased resistance. The experimental results show that: under the same sanding conditions, the amount of dust deposited on wet photovoltaic modules in the second group of sanding experiments is more than that on dry photovoltaic modules.

2) Rainwater has a blocking effect on photovoltaic modules and will accelerate the accumulation of dust on photovoltaic modules, thereby affecting the output power of photovoltaic modules. During the 5 times of watering in the dust accumulation experiment, compared with the photovoltaic modules with dry surface, the average relative output power loss of the photovoltaic modules with water droplets on the surface was 9.74%. Therefore, the water droplets on the surface of the photovoltaic module will affect the output power of the photovoltaic module to a certain extent.

3) The amount of water should be controlled when cleaning photovoltaic modules. The amount of water corresponding to the stage of a large increase in the output power of photovoltaic modules is the reasonable amount of water required for the purpose of cleaning the photovoltaic modules. Excessive water use not only wastes water resources, but also causes residual water droplets in photovoltaic modules Energy loss will cause the output power of photovoltaic modules to drop instead of rising. In the second half of the sand-spraying experiment, the output power of photovoltaic modules decreased to a certain extent with the increase of watering times. Controlling the amount of cleaning water is critical as excess water droplets can negatively affect the output power of photovoltaic modules.

The conclusions drawn in this study have certain reference value for the water cleaning of photovoltaic modules, which will help to further improve the output power of photovoltaic modules on the basis of saving water resources.