Agrivoltaics for rice growth

Image: Rauschenberger, Pixabay

Scientists in Bangladesh have investigated the potential of agrivoltaics in rice fields. They analyzed the economic viability of bifacial agrivoltaic projects in Vietnam, Bangladesh, China, Egypt, Brazil, and India.

From pv magazine

Scientists from Bangladesh’s East West University have developed a modeling framework to determine how agrivoltaic power plants could be deployed in rice fields.

“Our modeling should help policymakers and installers working on future agro-PV projects,” researcher Mohammad Ryyan Khan told pv magazine. “Very limited works have been carried out to date on agrivoltaics with major crops such as rice, wheat, corn, and maize.”

The researchers investigated the economic viability of bifacial agrivoltaic projects for the most common type of rice – Oryza sativa, which is also known as Asian rice. They focused on six locations: An Giang, Vietnam; Dhaka, Bangladesh; Jiangsu province, China; Damietta, Egypt; Rio Grande do Sul, Brazil; and Haryana, India. They considered location-specific weather conditions, PV system orientation, panel array row spacing, financing conditions, and the economic advantages of bifacial panels.

“For a given location and bi/monofacial panel array configuration, we find the time-varying irradiance on each point on the cropland and panel surface,” the scientists explained. “Since higher PV density penalizes the crop output of an agrivoltaic farm, we do a parametric analysis to find optimal row spacing to ensure the desired amount of rice production per unit of land area.”

Locations such as Damietta and Haryana are reportedly able to provide additional gains through higher energy yield, due to more favorable solar irradiance. The scientists found that financing conditions are also crucial in ensuring the economic viability of a project. They said that an agrivoltaic project for rice growth should ensure that at least 90% of the land is used for crop cultivation.

“We predict the net profit to be 22 to 115 times higher in AVs (with 90% rice yield constraint) compared to only producing rice in those land,” they explained.

The scientists described their methodology in “Agrivoltaics analysis in a techno-economic framework: Understanding why agrivoltaics on rice will always be profitable,” which was recently published in Advanced Energy.

“We are currently planning to set up a pilot facility and demonstrate its socio-economic impact,” Khan said. “We also want to create awareness and prospects for farmland owners in Bangladesh.”


Novel method to turn existing solar parks into agrivoltaic facilities

Image: NREL/Dennis Schroeder

An international research team has developed a new methodology to increase levels of pollination at ground-mounted solar plants. It involves the development of new vegetated land cover below and around solar parks.

From pv magazine

An international research team has developed a new approach to improve land use at ground-mounted solar plants, which they claim could be used to add important wildlife habitats or even agricultural activity to land already in use by a conventional PV system.

“We initially developed our approach for existing solar plants installed in the region of Apulia in southern Italy, but it could be utilized in other regions or countries with different vegetation,” Teodoro Semeraro, an environmental scientist at Italy’s University of Salento who led the research, told pv magazine.”It could also be used for new projects that include agricultural use or rooftop installations combining green roofs with solar power generation, where the agricultural aspect would have less importance.”

The approach would see new vegetated land cover cultivated below and around solar installations, as potential habitat for pollinating insects or for agricultural activities including beekeeping and medicinal herb production. This approach would provide a series of additional advantages such as reduction of maintenance costs of green areas in solar parks, fire risk reduction, potential development of small-scale agricultural activities, and positive media coverage, among others.

Local conditions

The scientists pointed out that the selected vegetation to be grown at the solar parks should be able to adapt to the ground’s environmental conditions, water scarcity, and nutritional deficiency. “Our approach may also consider non-indigenous species, but from the point of view of the landscape and the protection of local biodiversity, the use of indigenous vegetation is desirable,” Semeraro stated. “Moreover, the local species are adapted to the climate and the lack of water, which is chronic in Apulia, so they could respond better. But, having said that, the use of non-native species is technically feasible at conditions that respond to specific project needs.”

According to the research, Beekeeping at these sites would not require invasive structures and hives could be laid on the ground during the blooming time. “The biodiversity and ecosystem services could persist over time even after ground-mounted PV systems are dismantled and continuing to support population welfare at both local and larger scale, guaranteeing sustainability,” they further explained, noting that beekeeping may help overcome the issue of monoculture, which is typical of the Apulia region.

Holistic approach

The research listed a range of ecosystem services which solar parks could provide without additional human input, on the basis of the intrinsic value of the vegetation in sustaining ecosystem services. This would turn the solar parks into semi-natural areas, or Agro-Ecological Photovoltaic Gardens, which would host melliferous species blooming in different periods to be harvested and marketed as medicinal herbs. Furthermore, the solar panels may reduce the water stress for the vegetation, while improving soil quality thanks to their shading function.

When asked about what exactly defines agrivoltaics and make it differ from conventional ground-mounted solar facilities, Semeraro said that the crucial element is the presence of an agricultural enterprise in a project. “We cannot speak of agrivoltaics if a stakeholder in the agricultural field is not involved in the project or if there is no farm interested in the cultivation or use of the soil,” he stated. “There is a risk that a plant will be created without there being someone who cultivates it.”

The scientists introduced their approach in the study “An innovative approach to combine solar photovoltaic gardens with agricultural production and ecosystem services,” published in Ecosystem Services.

The group includes scientists from the University of Salento and the Institute of Science of Food Production C.N.R. Unit of Lecce, in Italy, as well as from the Glasgow Caledonian University in the United Kingdom.

“A transdisciplinary approach is important to share knowledge across the different stakeholders and bridge the information gaps typical of a sectoral perspective, creating a holistic vision of the involved professional skills and experiences,” the paper reads. “Its proper implementation requires the joint effort of all economic stakeholders together with technical and scientific experts to promote multifunctional land-use in ground-mounted solar farms.”

Author: Emiliano Bellini

Agrivoltaics for broccoli, cabbage

Image: Chonnam National University

Scientists in South Korea have combined PV generation with vegetable farming and have found that solar array shading provides favorable results for crops such as broccoli and cabbage.

From pv magazine

A research team at Chonnam National University in South Korea has looked at how solar power generation could be combined with broccoli and cabbage cultivation. The team found that the shading provided by a PV facility could improve the quality of crops.

Broccoli and cabbage need to be grown in places that receive full sun, which means between six and eight hours of sunlight per day, or very light shade. A lack of sunlight could result in thin, leggy plants.

“Because of its low light saturation points, broccoli may be a suitable crop to maximize famer’s profits and energy security through an agrivoltaic system,” the scientists said. “However, to date, there is limited information on the performance of brassica crops in agrivoltaics.”

The scientists built their agrivoltaic system with bifacial modules at a height of 3.3 meters. They achieved an average power generation per day of 127 kWh during the testing period. They claimed that their approach demonstrated the technical and economic viability of the proposed agrivoltaic solution.

“We found that the taste and the quality of the broccoli were not lower than those of a reference field without the solar array,” they said. “We also found no significant change in functional ingredients and metabolites that affect taste.”

The PV installation caused a significant reduction in the light hitting the crops, which in turn resulted in an improvement of their color.

“The color of broccoli is an important property that goes beyond appearance quality and is involved in consumers’ desire to purchase,” the scientists said.

They said that presence of the PV system reduced the agricultural yield by around 20%, compared to the reference field without solar. However, they said that the income generated by the solar array could more than compensate for such losses.

“The annual economic benefit from solar power was 10.4 times more than the broccoli production benefits,” the scientists said. “Therefore, farmer benefits will increase as they are cultivated in agrivoltaics compared to open field.”

The researchers presented their findings in “Agrivoltaic Systems Enhance Farmers’ Profits through Broccoli Visual Quality and Electricity Production,” which was recently published in Agronomy.

“In terms of land use efficiency, agrivoltaic is a good means of producing energy and food in Korea, which is a highly mountainous area,” they said.

Author: Emiliano Bellini

Mobile agrivoltaic system from the Netherlands

The mobile agrivoltaic array. Image: h2arvester

Created by a Dutch group of companies and research institutions, the mobile solar system may also be combined with an electrolyzer for hydrogen generation. Two prototypes are currently being tested by a farmer and a research institute in the Netherlands.

From pv magazine

A Dutch consortium has developed a mobile agrivoltaic system that is claimed to improve soil quality and biodiversity of agricultural fields.

Called H2arvester, the first prototype has been deployed on sugar beet land in Oude-Tonge, South Holland, and was inaugurated last week by Netherlands’ Agriculture Minister, Henk Staghouwer.

“The solar car concept was developed four years ago by my company and two other partners,” Marcel Vroom, the owner of design services provider Npk design, told pv magazine. The other two companies are L’orèl Consultancy and LTO Noord. “At the moment, there are two pilots being tested, the one in Oude-Tonge and one in Lelystad, at the research farm of the Wageningen University. Both systems will be operating for one year to test the effect on the yield and the land, to show that there will be no loss of agricultural production.”

Each car measures 12×6 m and is able to move slowly, at a pace of 10 meters per hour, and, during harvesting, it can be moved to the side. According to its developer, the system should cover up to 10% of an agricultural field, which would thus not lose its agricultural purpose. “They are movable arrays of solar panels, assembled on lightweight structures and supported on wheels, moving in pre-defined directions,” Vroom further explained.

The system could also be combined with an electrolyzer to produce hydrogen, which could then be used as a green fuel for agricultural applications. Residual heat coming from hydrogen generation may also be used to dry crops, such as oats, grass and alfalfa.”The solution to convert the generated kWh directly into hydrogen not only provides an autonomous production plant, but is also a solution to the need to balance the production and use of generated energy without worrying about reinforcements of the electricity network,” said Robert Jacobs, energy specialist at L’orèl Consultancy.

The project is part of the H2GO Program, which is an innovation program supporting the combination of electricity and green hydrogen. Partners of the projects are Kitepower, Npk design, L’orèl Consultancy, Rho, Accenda and TU Delft, among others. According to its creators, H2arvester is a circular energy model for a local and regional economy.

The local farmer Jacob Jan Dogterom invested €166,000 in the system located in Oude-Tonge, which consists of four solar cars hosting a total of 168 solar panels and an irrigation system that can also provide water to the surrounding area. “It is a pilot project, the investment is far from being complete. We will continue to build it and if we can develop this on a mass scale, it will only become cheaper,” the consortium said.

InnovationQuarter, the regional economic development agency for the Province of Zuid-Holland, subsidized around half of the project’s costs.

Author: Emiliano Bellini