Solar power for sustainable agriculture

Solar energy is becoming a leading trend in the renewable energy industry, especially as technology costs fall sharply and the shift towards renewable energy is spreading worldwide.

Báo Nhân dân•30/11/2025

Dau Tieng solar power plant, Tay Ninh province. (Photo: MINH PHUONG)

Solar energy is becoming a leading trend in the renewable energy industry, especially as technology costs have fallen sharply and the shift towards renewable energy is spreading worldwide . One of the most common ways to convert solar energy into electricity to meet human needs is by using solar panels.

However, according to experts, the development of solar power plants worldwide is revealing significant limitations regarding the environment and land resources. The photovoltaic production process uses toxic chemicals such as hydrochloric acid, sulfuric acid, nitric acid, and hydrogen fluoride, which can pose health risks, especially to production workers. A report by the Institute for Energy Research (IER) in the United States indicates that solar panels generate 300 times more hazardous waste than nuclear power plants for the same unit of energy supplied. Solar panels using heavy metals such as lead, chromium, and cadmium can harm the soil environment if they are crushed and buried.

In addition, large-scale utility-sized solar panels occupy a lot of space, inhibiting the growth of vegetation below and turning these areas into barren land.

In Vietnam, solar power has developed rapidly in recent years, especially in Ninh Thuan – considered the "solar energy capital" of the country. This boom has occurred amidst rapid economic growth, high energy demand, and sharply decreasing technology costs. However, large-scale solar power projects are occupying a lot of land, putting pressure on the environment. Most projects lack plans for disposing of solar panels at the end of their lifespan, while these devices contain materials and heavy metals that can cause pollution if disposed of through conventional landfill methods.

Around the world, many research groups have sought to overcome the limitations of flat-panel solar power by using concentrated solar power technology. This technology focuses sunlight into a small area to significantly reduce the number of photovoltaic cells needed. A group of scientists in China was one of the first to propose a model that separates the components of sunlight, where red and blue light are used for agriculture, and the rest is converted into electricity. However, this model is very expensive because it requires the use of expensive nano-optical films to separate the light, has low durability, and a focusing factor of only a few tens of times, making the technology only suitable for laboratory use.

Recently, a team of authors from Phenikaa University developed a new approach that overcomes the aforementioned shortcomings and is suitable for practical conditions after implementing the project "Research, design, and fabrication of an environmentally friendly photovoltaic-agricultural system based on concentrated solar energy technology," funded by the National Science and Technology Development Fund (Nafosted).

Associate Professor Vu Ngoc Hai, the project leader, said that instead of using a parabolic trough to create a straight-line convergence, the research team switched to using a Fresnel lens—an optical component that is thin, lightweight, inexpensive, and capable of concentrating light into a small point with a convergence coefficient of up to hundreds of times. When light is compressed so strongly, the area of the photovoltaic cell needed is reduced by hundreds of times, meaning less material, less toxic chemicals, less waste, and lower costs. This Fresnel lens is also an invention of the team through this project.

Associate Professor Vu Ngoc Hai further explained that at the convergence point, the research team placed a semi-reflective mirror to separate the components of natural light. Red and blue light (two light regions that plants absorb strongly) are transmitted through the mirror to the growing area. The remaining light, especially the infrared region which carries a lot of thermal energy, is reflected back and concentrated on the high-efficiency solar panel. Separating the light components at a small point reduces the surface area requiring filter coating by 25-30 times, allowing for the use of more durable, cheaper, and industrially produced coating techniques. This is a significant improvement compared to existing technologies worldwide.

The separated red and blue light sources are guided into optical fibers and redistributed using optical structures. This ensures even light distribution to plants, eliminating shadows and preventing yield reductions compared to models with widely spaced solar panels or panels mounted on greenhouse roofs. The high-energy reflected light is converted into electrical energy with higher efficiency than traditional flat panel technology.

According to the research team, this technology opens up potential applications in agro-photovoltaic models in Vietnam, especially in areas with high radiation intensity and a need to combine electricity production with crop cultivation. In the next phase, the research team aims to develop the system to a more complete level so that its practical application can be evaluated, with a view to transferring the technology to businesses and agro-photovoltaic models in the country.

To ensure scalability, the team collaborated with Myongji University (South Korea) – an institution with expertise in optics, materials, and renewable energy – to jointly develop a complete prototype system for experimental use. This collaboration allowed the team to conduct performance measurements under varying environmental conditions, including the tropical climate of Hanoi and the temperate climate of Seoul, South Korea. They evaluated the durability of Fresnel lenses and optical filters, and verified the stability of light distribution across plants. Initial test results showed the system offered higher energy conversion efficiency compared to traditional flat-panel models under the same radiation conditions, while providing sufficient red-green spectrum for plant growth, avoiding localized shading, and not reducing yield. The initial successes of the collaborative program were published in the Q1-ranked international journal Plos One.

According to representatives of the National Science and Technology Development Fund, the research project not only demonstrates the feasibility of next-generation photovoltaic-agricultural technology but also opens up great opportunities for Vietnam to join the group of countries possessing concentrated solar power technology for sustainable agriculture. With the aim of further optimizing optical materials, reducing costs, and building larger-scale prototypes in the 2025-2027 period, it is expected that the system can progress to field trials, transfer to businesses, and directly contribute to Vietnam's goals of green agriculture, circular economy, and renewable energy.

SNOWY LIGHT

Source: https://nhandan.vn/dien-mat-troi-cho-nong-nghiep-ben-vung-post926876.html