The expansion of renewable energies aims at meeting the global energy demand while replacing fossil fuels. However, it requires large areas of land. At the same time, food security is threatened by the impacts of climate change and a growing world population. This has led to increasing competition for limited land resources. In this context, the combination of photovoltaics and plant production — often referred to as agrophotovoltaic (APV) or agrivoltaic systems — has been suggested as an opportunity for the synergistic combination of renewable energy and food production. Although this technology has already been applied in various commercial projects, its practicability and impact on crop production have hardly been investigated. In this review, we give a short summary of the current state of the art and prospective opportunities for the application of APV systems. In addition, we discuss microclimatic alterations and the resulting impacts of APV on crop production. Our main findings are that (1) crop cultivation underneath APV can lead to declining crop yields as solar radiation is expected to be reduced by about one third underneath the panels. However, microclimatic heterogeneities and their impact on crop yields are missing reference and thus, remain uncertain. (2) Through combined energy and crop production, APV can increase land productivity by up to 70%. (3) Given the impacts of climate change and conditions in arid climates, potential benefits are likely for crop production through additional shading and observed improvements of water productivity. (4) In addition, APV enhances the economic value of farming and can contribute to decentralized, off-grid electrification in developing and rural areas, thus further improving agricultural productivity. As such, APV can be a valuable technical approach for more sustainable agriculture, helping to meet current and prospective needs of energy and food production and simultaneously sparing land resources.

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Agrophotovoltaic systems: applications, challenges, and opportunities. A review

The strategic engineering of solar energy technologies—from individual rooftop modules to large solar energy power plants—can confer significant synergistic outcomes across industrial and ecological boundaries. Here, we propose techno–ecological synergy (TES), a framework for engineering mutually beneficial relationships between technological and ecological systems, as an approach to augment the sustainability of solar energy across a diverse suite of recipient environments, including land, food, water, and built-up systems. We provide a conceptual model and framework to describe 16 TESs of solar energy and characterize 20 potential techno–ecological synergistic outcomes of their use. For each solar energy TES, we also introduce metrics and illustrative assessments to demonstrate techno–ecological potential across multiple dimensions. The numerous applications of TES to solar energy technologies are unique among energy systems and represent a powerful frontier in sustainable engineering to minimize unintended consequences on nature associated with a rapid energy transition. Managing the interactions and impacts of scaled-up solar energy production will require understanding of the relationships between technological and ecological systems. This Perspective proposes a framework that could help engineer beneficial outcomes from an energy transition.

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Techno–ecological synergies of solar energy for global sustainability

Implementation of agrophotovoltaics: Techno-economic analysis of the price-performance ratio and its policy implications

Combining agriculture and photovoltaics on the same land area gains in attention and political support in a growing number of countries accompanied by notable research activities in France, USA and Korea, amongst others. This study assesses the technical feasibility of agrivoltaic (APV), while it gives insights on how to design an APV system. Furthermore, it analyses the electrical yield and the behavior and productivity of four crops grown in Germany's largest agrivoltaic research facility installed in 2016 near Lake Constance within the research project APV-RESOLA by Fraunhofer Institute for Solar Energy Systems ISE. The German design differs from most other agrivoltaic approaches by allowing for a wide range of machine employment, facilitated by a vertical clearance of 5 m and a width clearance of up to 19 m. Crops cultivated under the APV system and on the reference field under a crop rotation scheme include potato, celeriac, clover grass and winter wheat. The land use efficiency measured by the Land Equivalent Ratio (LER) indicated a rise between 56% and 70% in 2017 while the dry and hot summer in 2018 demonstrated that the agrivoltaic system could increase land productivity by nearly 90%. Radiation simulations showed that deviating from full south by around 30° resulted in equal distribution of radiation on ground level, representing the basis for the agrivoltaic design. Considering climate change and increasing land scarcity, our overall results suggest a high potential of agrivoltaics as a viable and efficient technology to address major challenges of the 21rst century.

Combining food and energy production: Design of an agrivoltaic system applied in arable and vegetable farming in Germany

Large-scale development of solar-generated electricity is hindered in some regions of the U.S. by land use competition and localized social resistance. One approach to alleviate these coupled challenges is agrivoltaics: the strategic co-location of solar photovoltaics and agriculture. To explore the opportunities and barriers for agrivoltaics, in-depth interviews with solar industry professionals were conducted and findings suggest that the potential for an agrivoltaic project to retain agricultural interests and consequently increase local support for development is the most significant opportunity of dual use solar. Capable of increasing community acceptance, participants expect agrivoltaics to play an important role in future solar endeavors, especially in places where development may be perceived as a threat to agricultural interests. The results further reveal the interconnections among the various dimensions of social acceptance and suggest that the growth of agrivoltaics is contingent on market adoption of the technology through community acceptance and supportive local regulatory environments. As solar photovoltaic systems transcend niche applications to become larger and more prevalent, the dimensions of social acceptance, including the opportunities and barriers associated with each dimension, can help inform decision making to enhance the growth of agrivoltaics and thus photovoltaic development. The findings can help land use planners, solar developers, and municipal governments make informed decisions that strategically and meaningfully integrate agriculture and solar, and in turn provide multiple benefits including the retention of agricultural land, local economic development, and broad adoption of solar energy technologies.

Integrating solar energy with agriculture: Industry perspectives on the market, community, and socio-political dimensions of agrivoltaics

https://hal.archives-ouvertes.fr/hal-02111403/document

Agrivoltaic potential on grape farms in India

Summary The declining productivity of little millet (Panicum sumatrense) in a rural area in India necessitates finding a sustainable solution. A suitable composition of plant growth-promoting rhizobacteria (PGPR) in the rhizosphere of a crop is considered important for its optimum yield. Therefore, a study was undertaken to isolate and identify suitable bacteria and see their priming effect on the productivity of little millet. Rhizospheric soil samples were used to isolate bacteria on nitrogen-free Jensen's medium. Fast-growing rhizobacterial isolates FKK5 and DUM4, which exhibit significant selected plant growth-promoting activities, were selected. Little millet seeds were inoculated with selected PGPR and a non-native Azotobacter chroococcum before sowing. The inoculated plants were grown under semi-sterile poly-house conditions. Little millet inoculated with FKK5, DUM4, and A. chroococcum (5576) showed enhanced grain yield by 28.14%, 24.72%, and 20.43%, respectively, and enhanced total biomass yield by 23.08%, 21.87%, and 19.09%, respectively. The isolates were identified as Burkholderia sp. with 0.66% dissimilarity in 16S rDNA sequence with the most closely related species in the Genbank database. The native PGPR proved to be more effective compared to non-native PGPR as biofertilizers in restoring the productivity of the nutritionally important cereal.

Utkarsh S. Sharma

Papers

Agrivoltaic potential on grape farms in India

Priming effect of native rhizosphere bacteria on little millet (Panicum sumatrense)