According to the International Energy Agency, China installed 34GW of new photovoltaic capacity in 2016, which is more than twice that of the United States and accounts for half of the world's newly installed capacity. If clean energy represented by solar energy can replace the coal-fired power generation structure, it will greatly improve China's environmental situation. Huge investment in the field of clean energy is one of the key measures of Chinese governments at all levels. Installing photovoltaic panels will improve air quality, a cause-and-effect relationship we have always understood. But what about the other way around? Will the air quality that needs to be improved in turn affect the power generation of photovoltaic panels? The latest research from Duke University confirms our doubts. Based on NASA GISS global climate model data, the study found that particulate matter in air pollution can significantly reduce photovoltaic power generation efficiency, even reaching more than 17%. Short-wave solar radiation is blocked by dust and particles and is absorbed and scattered. This phenomenon, called solar dimming, reduces the radiation intensity received by photovoltaic modules, resulting in power generation losses. According to the study, based on China's current photovoltaic power generation capacity, the power loss caused by haze is as high as 11GW, which is nearly one-third of China's newly installed photovoltaic capacity. It is worth noting that man-made particulate matter has a greater impact on photovoltaic power generation than natural dust. The researchers sampled and analyzed the composition of the sediments on the surface of the photovoltaic modules and found that only 8% was non-dust particles, that is, generated by human activities. Although this 8% sounds nothing to worry about, because it contains organic carbon, carbon black and other ingredients, carbon atoms have a stronger ability to absorb sunlight; and because the particles are smaller, sunlight is more easily scattered. Therefore, the loss of power generation efficiency caused by human activities is even greater than the dust that accounts for 92%. Yingli Group, one of the world's largest photovoltaic module manufacturers, feels this deeply. Ni Jianxiong, deputy general manager of the technology center, said that by comparing and monitoring the outdoor power generation of photovoltaic modules of automatic cleaning robots and conventionally installed modules, Yingli found that: in Xingtai, Hebei In "famous" haze cities such as Beijing and Baoding, the power generation during haze periods can be reduced by more than 80%. When the haze is the most serious, there is almost no power generation. Drew Shindell, a member of the research team and a professor in the Department of Civil and Environmental Engineering at Duke University, said that these particulate matter generated by human activities have caused China to face more serious photovoltaic power generation losses than other countries. According to research, in central and eastern China, when photovoltaic modules are scrubbed once a month, particulate matter will cause the photovoltaic module power generation efficiency to be reduced by 17%~25%; if the scrubbing interval is 2 months, the power generation efficiency of the photovoltaic module will be reduced by 25%~ 35%. China's large ground power stations do not have unified standards for scrubbing. They generally decide when to scrub by monitoring power generation. Sanas New Energy Technology Co., Ltd., headquartered in Qingdao, Shandong Province, specializes in the operation and maintenance of photovoltaic power plants. The company’s general manager Geng Wenqiang told chinadialogue that from the perspective of component maintenance, large-scale ground power stations in northern China basically have to ensure The standard scrubbing is four times a year. In the case of serious pollution, the number of scrubbings can be increased appropriately according to the site conditions. According to this study, the daily power generation of photovoltaic modules after scrubbing will increase by 50%, which is a significant effect. Ni Jianxiong said that there is no doubt that it is very important to keep photovoltaic panels clean. While improving power generation efficiency, it can also effectively maintain photovoltaic modules, because long-term accumulation of particulate matter may cause a large amount of heat in the modules, causing hot spots and threatening the life of the modules. However, a more realistic issue for businesses is the water required for scrubbing. In the northwestern region of China, which is rich in light resources, water is often much more precious than electricity. It is obviously not worthwhile to use water to increase power generation. Geng Wenqiang said that because scrubbing requires a large investment of water resources, which is a considerable cost, companies need to make a comprehensive comparison of scrubbing investment and actual revenue from power generation to determine the frequency of scrubbing. More professional photovoltaic operation and maintenance companies will also use the results of photovoltaic big data analysis and mining to find the best cost-effectiveness for cleaning. Distributed power stations are actually the main victims of the impact of haze. Unlike the regular scrubbing and maintenance of large-scale ground power stations, small rooftop projects generally only rely on natural weather scrubbing such as rain and snow after completion, and lack later operation and maintenance, which further aggravates the impact of haze pollution. Zhang Weihong, public relations director of Aikang Technology, told chinadialogue that “very few residential users would think of climbing up to the roof of their home to clean photovoltaic panels.” Poor air quality compromises clean energy power generation; poor development of clean energy is not conducive to environmental improvement. Zhang Weihong said frankly that for investors in the photovoltaic field, frequent haze weather has increased a systemic risk that is difficult to control. The main source of particulate matter that affects photovoltaic power generation efficiency in China is human activities, so the government has greater potential to reduce emissions and reduce pollution. The government has a variety of tools to choose from, including fuel selection, emission rights pricing, and preferential policies for renewable energy. The benefits are also obvious. In addition to the increase in photovoltaic power generation, considering the health risks of inhalable particulate matter, it will undoubtedly greatly improve people's health. In addition, this also shows from another perspective that the compromise approach of developing photovoltaic power generation while continuing to build coal-fired thermal power stations may not be a good idea, because the latter will greatly affect the operation of the former. Source: Chinadialogue (2017-10-12) (compiled by PIDC)
