Since the emergence of the "fish-light complementarity" model in my country, it has always been a hot topic.
Some say that solar panels can prevent direct sunlight from hitting the water surface, which is conducive to cooling the water surface and promoting fish farming; some say that after the photovoltaic panels block the sunlight, the photosynthesis efficiency in the fish pond will be reduced and the breeding density will be reduced; there are also claims that a large number of columns are erected in the photovoltaic fish pond, which is not conducive to fishing.
Which statement is more accurate? In fact, this is also related to the specific types and methods of fish farming.
In terms of breeding types, for the most shade-loving breeding products such as shrimp, blue crabs, soft-shelled turtles, river crabs, yellow catfish, and sand catfish, photovoltaic panels block the sunlight and lower the water temperature, which is the best choice.
In a salt field shrimp breeding area in Binzhou, Shandong, which was once praised by CCTV, the photovoltaic panels of the "fish-light integration" project were installed in a 25° tilt angle fixed manner, which can not only achieve the best power generation effect, but also shade and cool the shrimp pond. After shading, the water temperature drops by 1-2 degrees, providing a better growth environment for salt field shrimp.
It is understood that the salt pan shrimp in the "fish-light integrated" pond matures 3-5 days later than ordinary salt pan shrimp, and its meat is firmer and more delicious, making it more popular among consumers. Every year, about 20 million salt pan shrimp swim from here to the tables of diners across the country.
There are also crabs. In 2023, Huazhuang Village, Wujian Town, Jiangdu District, Yangzhou, Jiangsu Province built a 15-megawatt "fish-light complementary" project, with the upper layer used for photovoltaic power generation and the lower layer for crab farming. Local farmers said, "At the beginning, everyone was worried whether the photovoltaic panels would affect the growth of crabs and lead to a reduction in crab production." After raising them, they found that "it was really delicious." This is because crabs will shed their shells several times during their growth. Summer is the most vulnerable time for crabs, and they cannot withstand the scorching sun and bird attacks. The "fish-light complementary" project just makes up for this defect and has no effect on crab feeding and fishing. According to Guangming Daily in July this year, after the project was put into operation, the first batch of crab farmers in the village now have a net profit of more than 3,000 yuan per mu. The Datang Yixing Yangxiang 80MW fish-light complementary composite photovoltaic power generation project in Yangxiang Town, Wuxi, Jiangsu, also laid photovoltaic panels above the crab pond, with more than 1,400 acres of crab ponds, water power generation and underwater crab farming. According to the tracking statistics of the local Agriculture and Rural Affairs Bureau, after the photovoltaic panels are shaded, the water temperature drops by 2 degrees Celsius, which can not only provide shade but also reduce the occurrence of crab diseases.
It is particularly noteworthy that the model of breeding under photovoltaic panels has also directly reduced the breeding costs of local farmers: the rent of crab ponds is borne in part by photovoltaic enterprises, and the rent price of farmers has been reduced from the original 1,000 yuan/mu to the current 200 yuan/mu.
Similar to this is the 200MW fish-light complementary photovoltaic power generation project in Songhu Town, Nanchang, Jiangxi. It is understood that the project was invested by the State Energy Group with an investment of about 200 million yuan. After the completion of the project, the group and local farmers signed an agreement to rent the water surface back to farmers for organic breeding at a price far below the market price.
The first batch of farmers in the village who participated in "water power generation and underwater fish farming" contracted 400 acres of water surface for breeding grass carp, silver carp, crucian carp, etc. Due to the layout of photovoltaic panels, it can effectively reduce the high temperature and hypoxia of fish in summer, and can also inhibit the reproduction of algae. The first batch of more than 300,000 fish fry released are growing well.
These actual cases show that the fish-solar complementary project effectively helps fish and shrimp cool down through the combination of photovoltaic power generation and shading measures, providing a more suitable breeding environment. At the same time, the rental costs that farmers need to pay will be less.
As for the fishery breeding model, many farmers have a common concern: how to solve the fishing problem?
In the harvest season of traditional fish ponds, farmers generally use nets or drainage to catch fish, while a large number of columns are set up in photovoltaic fish ponds. The distance between the columns is generally 5 meters. There are about 27 columns in an acre of water. It is difficult to pull a large net between the densely packed columns to catch fish. Is there a better way to catch fish?
With this doubt, I checked several successful cases of photovoltaic fish ponds. It turned out that as early as the beginning of the design of the integrated fish-light model, researchers had given a solution:
Solution 1: When building the photovoltaic fish pond, the original pond was renovated, 75% of the area was placed with photovoltaic panels, and the remaining 25% was designed as a deep water area, used as an area for fish feeding and fishing. In this way, when fishing, the water in the area where the photovoltaic array is located will be discharged first, and the fish will be concentrated in the deep water area, and then fished. Compared with the traditional "pull net-drain-pull net" method, the fishing time will be greatly shortened, and the damage to the fish itself will also be reduced.
Solution 2: Set up a fixed feeding platform in the fish pond, and leave a space of several hundred square meters around the platform. When fishing, first use fish feed to attract the fish feed to the scattered feed platform, and then use the pulling net method to fish.
Solution 3: Use the tank fish farming model. In Xixi Township, Xichang City, Sichuan Province, there is such a fish farming base. Among the 1,100 mu of water area, 75% are paved with photovoltaic panels, and only 25% of the water area is used to build water tanks for fish farming. In the water tank fish farming mode, fish can be fed in a more intelligent mechanized feeding method. After accurate calculation, the fish in a water tank are fed four times a day, 50 kilograms each time, and the feeding is more accurate and uniform. The power source required by the water tank system is all supplied by the photovoltaic power generation system. This model not only cleverly avoids the inconvenience of fishing caused by photovoltaic panels, but also helps the traditional fish ponds to carry out facility-based, intelligent, and large-scale transformation, and achieve a bumper harvest of "fishing, electricity, and environmental protection".
Having said so much, can it be done to build photovoltaics in fish ponds? Of course it can be done. Although compared with the traditional photovoltaic development model, the development of fish-light complementary projects involves more difficulties and is more detailed, as long as all parties formulate reasonable policies, clarify the rights and interests of all parties, and strengthen supervision and coordination on the basis of equality and consultation, it can still be solved after all.
At present, all parts of the country are vigorously developing fishery-photovoltaic complementary projects. A large number of projects have been built and connected to the grid, making important contributions to promoting rural economic development, increasing farmers' income, and promoting the development of ecological agriculture.
