Tashkent, Uzbekistan (UzDaily.com) -- In the context of global climate change, as well as the aggravation of challenges and threats to food and energy security, one of the promising ways out for countries is the active introduction of innovative areas in agriculture, including agrovoltaics (APV), which allows to combine energy production and farming.

The concept of agrovoltaics was originally proposed in 1982 by German scientists A. Goetzberger and A. Zastrow as a means of modifying solar power plants to increase yields on the same area.

Their idea was to raise the solar collectors 2m above the ground and increase the distance between them to avoid excessive shading of the crops.

According to experts, this method has the following advantages:

Firstly, there is great potential for using solar energy panels in regions with high population density or limited area, since it allows generating energy in a relatively small agricultural area.

For example, in the Indian project, scientists calculated that on an area of 34 thousand hectares of vineyards, the APV capacity will be 16 thousand GW / h, which is enough to meet the energy needs of more than 15 million people (1 hectare generates 0.47 GWh, which provides electricity for about 500 people).

In total, according to some data, by 2021 the total capacity of agrovoltaic installations around the world has reached 14 GW.

Secondly, the method is ideal for semi-arid and arid regions where crop production often suffers from the adverse effects of high solar radiation and associated water loss.

As scientific studies have shown, the shading of crops can reduce the evaporation of moisture from the soil by 40%, which significantly reduces water consumption.

Thirdly, the productivity of the harvest of individual crops is increasing. Studies have shown that the use of APV can increase land productivity by up to 70%.

Fourth, in addition to the impact on crop production, the introduction of APV increases the profitability of agriculture by generating additional income from energy production and can further improve off-grid electrification of rural areas as part of a decentralized energy system.

Today, only a few developed countries in the world have research projects in this area.

For example, in the United States in 2018, a small APV research facility was installed in Arizona, and it is planned to create additional test sites in rural Arizona and in the north of the country.

In Germany, the Fraunhofer Institute for Solar Energy Systems (Fraunhofer ISE) built a 0.3 ha, 194 kWh APV research plant in Southern Germany in 2016 and three more pilot plants in Chile to study APV and its impact on field crops in different climatic zones.

In Italy, three APV projects have been implemented with a total capacity of up to 1500 kW using suspended solar modules (4-5 m high) with sun tracking technology.

An APV field in Abruzzo, a region of Italy, uses 67 off-grid solar panels to grow tomatoes, watermelons, wheat and generate 800 kWh of electricity.

In Japan, a number of small APV plants have been built since 2004. These systems, which consist of photovoltaic panels mounted on poles with a ground clearance of 3m, combine solar energy production with the cultivation of various local food crops such as peanuts, yams, eggplant, cucumbers, tomatoes, taro and cabbage.

In 2013, Japan introduced the first government support program and registered more than 1900 agro-electric installations in 2018.

While in Europe, America and Japan, mostly small research and a few medium-sized commercial APV installations have been established so far, China is already implementing this technology on a large scale.

The largest APV plant to date, with a capacity of 700 MW, was put into operation in 2017 at a goji berry (medicinal plant) plantation in Ningxia Autonomous Region. Currently, work is underway to bring its capacity up to 1 GW.

Project implementers Baofeng Group and Huawei note that the solar panels are equipped with a sunflower tracking system, which greatly improves the efficiency of photovoltaic cells and increases electricity generation. And the installation of solar panels at a height of almost 3 m does not interfere with field work and harvesting.

According to Huawei, after completion of the project, it will save 557.6 thousand tons of coal annually, reduce CO2 emissions by 1.6 million tons, sulfur dioxide by 51 thousand tons, nitrogen oxide by 26 thousand tons and dust by 462 thousand tons per year.

At the same time, one of the main issues is that the issues of increasing the yield of various crops with the use of APV are not fully understood.

In particular, scientists note that when using APV, solar radiation is reduced - and here, geographic and climatic conditions, as well as the cultivation of various types of agricultural products, affect the yield.

Thus, according to the results of a study conducted in 2016, it was found that a decrease in solar radiation by 20% leads to a decrease in rice yield by 20%. Similar figures were obtained from the study of the effect of shading on wheat yield.

In turn, in potatoes, the number of tubers and the yield usually decreased during shading, but in regions with high solar radiation, on the contrary, it increased.

However, in another field experiment in which various varieties of lettuce were grown on an APV plant, it was found that with a reduced density of photovoltaic modules and a distance between rows of panels of 3.2 m, radiation was available at the level of 73%. Lettuce yields averaged 81-99% of full sun yields, while two varieties outperformed control values.

Another experiment, carried out in a dry Mediterranean climate, showed an increase in the yield and fruit of a tomato with a decrease in total sunlight by 25-26%. Plant height also increased under these conditions. However, a higher degree of shading (50-75% of full sunlight) had adverse effects and led to reduced fruit yields.

Similar results were obtained for sweet peppers grown in the Negev Desert (Israel), where moderate shade (12-26%) resulted in increased yield and plant height.

The most promising option is the integration of agrovoltaics in those areas where supporting structures are already used (vineyards, intensive fruit growing, etc.). This approach is actively used by the French wine company "Sun’Agri". She expects that the application of APV in intensive fruit production and viticulture will lead to water savings, protection of fruits from sunburn, and preservation or even increase in yield by reducing losses due to extreme weather events (frost, hail, high winds).

This aspect may become even more relevant in the future in the main wine-growing regions, as the area suitable for viticulture is predicted to decline sharply by 2050 due to the effects of climate change.

A study modeling the APV potential of Indian grape farms found that these farms’ annual income could be increased 14 times compared to conventional farms without APV while maintaining grape yields.

In general, despite the fact that at present agrovoltaics is mainly at the stage of research and testing of technologies, in the future APV can become an important component of the agricultural systems of the future, solving some current and future social and environmental problems, such as climate change, the growth of global demand on energy, food security and land use.

For Uzbekistan, taking into account its climatic conditions, it is important to conduct field research on the prospects for the introduction of agrovoltaki in densely populated and desert regions of the country.

If positive results are achieved, agrovoltaics can turn into an effective tool for raising agriculture to a qualitatively new level, rationalizing the use of declining water resources and developing a decentralized power supply system for the population, thereby increasing the country’s food and energy security.