How Can Agricultural Photovoltaic Achieve a Win-Win Situation?

As the global population is expected to increase by 1.2 billion people in the next 15 years, the demand for meat, eggs, and dairy products will also continue to increase. This demand will need to meet the food supply of over 7 billion people, as well as the percentage of fresh water required for crops, as well as the electricity demand that continues to grow at a rate that even exceeds population growth. Faced with this series of challenges, we need to consider how to take effective measures to address them. Can we combine them? Let's take a look at adding solar energy to farmland and some of the accompanying benefits and challenges it brings.

 The problem with solar panels is that they require a lot of space to generate a large amount of electricity. Agricultural photovoltaic power generation, also known as APV, combines agriculture with power generation by cultivating under the cover of solar panels. The main problem with solar panels is that the ground below cannot be used, mainly due to the small space between the panels, which is not enough for modern agricultural equipment to pass through. When there is more space left between solar panels, crops can be planted there, and even small livestock such as chickens, geese, and sheep can be grazed. These animals are beneficial for solar power generation because they reduce the cost of maintaining vegetation growth and do not pose any risks to the battery itself.

However, the land between rows will be shaded for certain hours of the day. There are many variants currently being actively studied, where panels can be installed with actuators instead of fixed panels, allowing the panels to tilt in one or two directions, thereby achieving optimization of solar energy and plant growth. This is particularly important for the early growth stages of certain crops. How about planting crops directly under the panel? You may think that solar panels casting shadows on plants is a bad thing, but the way photosynthesis works makes things interesting. Plants grow and thrive using carbon dioxide with the help of sunlight. After reaching a certain threshold called the light saturation point, plants cannot absorb more energy, so they need to eliminate excess energy by evaporating water. If we oversimplify, we can divide plants into two groups: shade plants, which are particularly useful when combined with solar panels because solar panels clearly block some of the available sunlight. Nowadays, sunny plants are sometimes referred to as shade intolerant plants. These plants require more sunlight, but they may also suffer from excessive sunlight exposure. When any plant reaches the threshold, they will suffer from "sunburn" and "heat stress" like humans, leading to increased water evaporation.

According to a report by the German Solar Energy Research Institute, almost all crops can be grown under solar panels. However, in areas with insufficient sunlight, there may be some yield losses for plants that require sunlight, such as wheat and millet, which require sufficient sunlight to grow well. Researchers are studying which panels and settings are most suitable for growing which crops. Some plants require larger gaps between panels, some plants require modified panels, and some legumes require shorter varieties to be selected. The main shade tolerant crops for agricultural photovoltaic power generation have achieved great success, and the crops you can see in the agricultural market, such as lettuce, spinach, potatoes, and tomatoes, have all grown well, which shows us the potential of agricultural photovoltaic power generation. In the RESOLA project conducted in the Konstan Lake region of Germany from 2016 to 2018, they demonstrated that in the relatively humid and cold years of 2016, APV crop yields were 25% lower than those of solar farms, but in the dry and hot years of 2017 and 2018, APV crop yields exceeded the reference field, indicating that APV may change the rules of the game in hot and dry regions.

Let's turn our attention to the Netherlands, despite its small size, it is the world's second largest food exporter!They planted plants directly below the solar panel, and the solar panels were placed in alternating rows facing east and west. This can maximize solar energy production while also protecting plants from the impact of strong winds.

The quantity and quality of fruits produced under the panel are the same or better than those produced under traditional plastic tunnels. For farmers, a major benefit is that it saves the workload of managing plastic tunnels, which are easily damaged by hail and summer storms. In such cases, fruits may not be sold due to damage, but they must still be received in any case.Research by the US Department of Energy has shown that 95% of photovoltaic modules can withstand hail without damage. The temperature below the solar panel is several degrees lower, which not only makes farm workers feel more happy, but also reduces irrigation water by 50% compared to the reference field. Crops and their limited water evaporation actually keep the panels cool. Solar panels actually do not like heat because it reduces their energy efficiency; The lower the panel temperature, the more energy it provides. Therefore, based solely on this, agricultural photovoltaic seems to be a winning strategy. If we convert a small portion of our agricultural electricity consumption into agricultural photovoltaic power generation, most of our energy needs can be easily met. With the additional benefits of reducing water consumption, agricultural photovoltaics can also change the game rules of the world's heat and drought.

So, what is preventing us from launching this dual purpose, game changing system on a large scale? Is there any problem? Energy production is different from agriculture, which may hinder farmers from accepting this technology, but sadly, the actual obstacles are mundane and somewhat frustrating. Ultimately, it is not in my backyard option and free market. Let's start with the avoidance group, not all renewable energy solutions have received a warm welcome. A typical example is clearly that the nuclear power plant near your home will be boycotted. Therefore, in order to maintain appropriate local support, it is best for agricultural photovoltaic systems to be operated by local farms, energy cooperation communities, or regional investors. As part of agricultural policy, the EU provides direct payments for land primarily used for crops. Therefore, an important issue is whether farmland will lose its eligibility for financial support due to the use of agricultural photovoltaics. Whether land is primarily used for agriculture is decisive in its purpose. In the European Union, according to building regulations, agricultural photovoltaic systems are usually considered physical structures and therefore require building permits. For example, in Germany, rural areas are usually prohibited from doing so unless it does not conflict with a range of public interests. However, agricultural photovoltaics have not yet been included in the public interest list.

Agricultural photovoltaic power generation is a very promising concept that should be mainly deployed in areas where synergistic effects can be achieved, which can reduce the water demand for crop production. If the regulations for solar energy can be improved, we can overcome bias, which will help our food supply and shift us towards cleaner energy.