In early summer, among the green mountains and waters of Pu'er, Yunnan, coffee trees are quietly growing under the shade of photovoltaic panels. This is not only the core production area of the "Coffee Capital of China", but also the birthplace of the first batch of "coffee light complementary" power stations in the country - the Huaneng Coffee Factory composite photovoltaic power generation project. Recently, with the last group of photovoltaic arrays connected to the grid, this photovoltaic power station with an installed capacity of 30000 kilowatts and an average annual power generation of over 50 million kilowatt hours has been officially put into operation. It connects the ecological value of green mountains and rivers with the innovative practice of green energy through a cup of "photovoltaic coffee". The story begins with the coffee plantation in Simaogang Town, Pu'er. The coffee cultivation here has a long history, but it is difficult due to the scarcity of land resources and low added value of products. Farmers basically rely on the weather to make a living. The builders of China Huaneng have turned their attention to the sky above coffee plantations in order to break through the limitations of traditional coffee cultivation. They have conceived the idea of "dual use of sunlight" - installing photovoltaic panels above coffee trees, generating electricity on the panels, and planting coffee under the panels. Can this achieve "one piece of land, two types of income"? With this question in mind, they set up two sets of photovoltaic panels in the farmer's coffee garden and embarked on a suspenseful "light and shadow experiment". Can beans grow well with such a big board blocking the sun? ”The coffee farmers crouched under the panels, staring at the shadows under the photovoltaic panels and muttering to themselves. The staff shuttled around with spectrometers on their backs, using data to unravel doubts: the coffee trees here are neutral plants, neither "sun hungry" like light loving crops nor "light sensitive" like shade tolerant crops. The key is to find the golden balance between light and shade. After hundreds of observations, they discovered the "light and shadow code": when photovoltaic panels are installed with a horizontal spacing of 5 centimeters, a vertical spacing of 20 centimeters, and a height of 3 meters above the ground, the scattered light formed is like customizing a "soft light filter" for coffee trees. In summer, the temperature under the board is 3 to 5 degrees Celsius lower than in the open air, resulting in reduced leaf transpiration and stronger root systems; In winter, photovoltaic panels become a "thermal barrier", and when the cold wave arrives, the coffee leaves under the panels still stretch, reducing the impact of cold damage by 60%. More intuitively, in the experiment of adjusting the spacing between the brackets, a 4-meter spacing would cause spots to appear on the edges of the coffee leaves. When adjusted to 5 meters, the leaves immediately became shiny, and a 15 centimeter gap between the boards allowed rainwater to evenly penetrate the roots. Even coffee farmers exclaimed, "The boards are like a breathing sunshade, and the longer the beans, the more energetic they become." This confirmed the feasibility of the model, and the builders launched a "millimeter level competition" on a hill at 22 degrees north latitude. In order to find the optimal location for the symbiosis of photovoltaics and coffee, they carried a solar altitude angle measuring instrument to measure every inch of the mountain slope. After the site selection was determined, the drone lifting equipment hovered in the mountains, and the builders leaned on steep slopes to calibrate each bracket with a laser rangefinder. The 3-meter-high flexible bracket, 5-meter wide span, and 5-20 centimeter wide inter plate gap were all the result of repeated "light and shadow experiments". Nowadays, on 740 acres of sloping land, 2350 sets of photovoltaic panels are like domes, and coffee trees in the "exclusive sunroom" have lush green leaves and plump and round fruits. In the early morning, the sunshine slanted from the east, and in the afternoon, the board blocked the strong light from the west. The sunlight weaved mottled light and shadow through the gaps on the ground, as if laying an "ecological carpet" that generates electricity for the coffee garden. The arrival of the "coffee light complementary" model has gradually transformed the once barren land. The photovoltaic array is like a huge ecological umbrella, reducing water evaporation caused by sunlight exposure, fixing the soil with coffee tree roots, and increasing humus year by year. Farmers have found that even earthworms have become thicker, and the slopes during the rainy season are no longer covered in mud and sand, replaced by lush coffee forests. What surprises farmers even more is the change in income: land rent has been guaranteed, participating in project construction has increased gig income, the quality of caffeine under the board has been improved, and the purchase price has increased. Coffee bean processing factories come here because of their reputation, and coffee farmers aspire to build roasting production lines at their doorstep, allowing "photovoltaic coffee" to go far away. In Yunnan's Pu'er, Dali, Lincang, Baoshan, Diqing, Nujiang and other Lancang River basins, such stories are spreading. Huaneng Lancang River Company has woven a green energy network on the land of Yunling using the "photovoltaic+" model: 86 photovoltaic power stations are connected to various industries such as "agricultural light", "tea light", "animal husbandry light", etc. The installed capacity of photovoltaic projects exceeds 5.8 million kilowatts, and the annual power generation exceeds 6.4 billion kilowatt hours, contributing both abundant green energy and increasing farmers' income. (New Society)