Agrivoltaics Crop Production

INTRODUCTION

The global challenges of climate change, energy scarcity, and food security necessitate innovative solutions that optimize resource utilization while minimizing environmental impacts. Agrivoltaics crop production which involves the dual use of land for agriculture and solar energy production, has emerged as a promising approach to address these pressing issues. By integrating solar panels with crop production, agrivoltaics systems aim to achieve a balance between energy generation and agricultural productivity, thus contributing to sustainable land use and renewable energy targets (Dupraz et al., 2011).

The potential benefits of agrivoltaics extend beyond energy production. For instance, studies have highlighted how the shading effect of solar panels can influence soil moisture and temperature dynamics, potentially benefiting crops in arid regions. Moreover, research indicates that agrivoltaics can alter microclimatic conditions, such as light intensity and temperature, which may improve crop performance in some contexts (Marrou et al., 2013; Hassanpour Adeh et al., 2018). Despite these advantages, significant gaps remain in understanding the agronomic implications of these systems, particularly their effects on crop yield, soil health, and overall ecosystem function.

Recent work has also called for a standardized definition and methodology for assessing agrivoltaics to ensure consistency across studies and applications (de Ruijter et al., 2024a). Additionally, advancements in measuring light interception by crops under solar panels (de Ruijter et al., 2024b) and understanding species-specific responses, such as berry shade tolerance (Hermelink et al., 2024), highlight the need for further interdisciplinary research to optimize agrivoltaics design and implementation. This growing body of research underscores the importance of carefully designing agrivoltaics systems to maximize their dual benefits while addressing the challenges associated with their deployment.

LITERATURE REVIEW

2.1 Agrivoltaics Systems

Agrivoltaics systems represent an innovative approach to land use that strategically places solar panels above or around crops to optimize light distribution for both energy generation and agricultural productivity. These systems leverage the partial shading provided by solar panels to influence microclimatic conditions, including temperature, light intensity, and soil moisture.

Research by Marrou et al. (2013) demonstrates that this shading effect can significantly reduce evapotranspiration and temperature stress, which in turn enhances water use efficiency. This benefit is particularly valuable in water-scarce regions, where optimizing water resources is critical for sustainable agriculture.

Beyond water efficiency, agrivoltaics systems have been shown to contribute to biodiversity and soil conservation. By modifying the local microclimate, they create conditions that can promote diverse plant and insect populations, which are essential for ecosystem health and resilience (Dupraz et al., 2011). The shading provided by solar panels can also mitigate soil erosion and improve soil moisture retention, further enhancing soil health and stability.

This dual-purpose approach not only maximizes the productivity of agricultural land but also supports broader environmental goals, such as reducing greenhouse gas emissions and promoting renewable energy. Despite these promising benefits, the design and implementation of agrivoltaics systems require careful consideration to balance the trade-offs between crop productivity, energy generation, and ecological impacts, underscoring the need for further interdisciplinary research in this emerging field.

2.2 Crop Performance Under Solar Panels

Research highlights that light quality and intensity are pivotal factors influencing photosynthesis and crop yields. Agrivoltaics systems, by modifying light conditions under solar panels, create both opportunities and challenges for crop performance.

Studies have shown that certain shade-tolerant crops, such as lettuce and spinach, demonstrate resilience and even improved growth under the partial shade provided by solar panels. This is attributed to the reduction in heat stress and improved microclimatic conditions that favor these crops (Hassanpour Adeh et al., 2018).

Conversely, crops with higher light demands, like maize, may experience yield reductions due to insufficient light penetration under shaded conditions. This trade-off underscores the critical need to understand species-specific responses to shade. For example, optimizing light interception by crops under solar panels using tools like PARbars has been proposed to address these challenges, enabling better alignment of agrivoltaics designs with crop requirements (de Ruijter et al., 2024).

Moreover, a meta-analysis of berry shade tolerance further supports the importance of crop-specific adaptations in agrivoltaics systems, as different species exhibit varied responses to the altered light spectrum and intensity (Hermelink et al., 2024). These findings emphasize the necessity of designing agrivoltaics systems that are tailored to the specific light and growth requirements of the crops being cultivated. Such optimization is key to maximizing the benefits of agrivoltaics for both energy production and agricultural productivity.

2.3 Soil Health and Microclimate

Agrivoltaics systems significantly influence soil health by modifying soil moisture dynamics and temperature regimes, which in turn affect soil microbial activity and nutrient cycling. The shading effect of solar panels reduces direct solar radiation, leading to lower evaporation rates and enhanced soil moisture retention.

This is particularly beneficial during dry periods, as it provides crops with a more stable moisture supply, which is critical for maintaining plant growth and soil microbial processes (Armstrong et al., 2016).

However, the increased soil moisture under solar panels must be carefully managed to avoid potential issues such as waterlogging, which could disrupt root oxygen availability and microbial activity. The balance between beneficial moisture retention and excessive wetness highlights the need for site-specific agrivoltaics designs and management practices.

Additionally, temperature regulation under agrivoltaics systems contributes to a more stable microclimate. By moderating extreme temperature fluctuations, these systems can create favorable conditions for microbial communities, which play a vital role in nutrient cycling and soil organic matter decomposition (Dupraz et al., 2011). The interplay between altered soil temperature and moisture dynamics under agrivoltaics systems thus represents a promising avenue for enhancing soil health while supporting sustainable crop production.

Further research is needed to understand the long-term implications of these microclimatic changes on soil health, including their effects on microbial diversity, carbon sequestration, and nutrient availability, to optimize agrivoltaics systems for both productivity and ecological benefits.

RESEARCH GAP

Despite advancements in agrivoltaics, significant gaps remain in understanding:

1. The interaction between solar panel configurations and crop physiology, including photosynthesis, evapotranspiration, and yield.
2. Long-term impacts on soil health and microclimatic variables.
3. Optimal designs for diverse crop species and environmental conditions.

HYPOTHESIS

Agrivoltaics systems, through strategic light-sharing and microclimatic modifications, can enhance crop water use efficiency, reduce disease pressure, and maintain or improve crop yields while maximizing solar energy production.

 OBJECTIVES

1. Evaluate the effects of solar panel configurations on crop growth, yield, and physiological processes.
2. Assess changes in soil health, disease pressure, and microclimatic variables in agrivoltaics systems.
3. Identify optimal agrivoltaics designs for different crop species and environmental conditions to balance agronomic and energy outputs.

MATERIALS AND METHODS

6.1 Experimental Design

6.1.1 Field Experiments

Field experiments in agrivoltaic systems are structured to address dual objectives: optimizing renewable energy generation and sustaining agricultural productivity on the same land. A foundational aspect of these experiments involves evaluating how different solar panel configurations influence crop performance.

Fixed-tilt panels, which remain stationary at a set angle (e.g., 15°, 30°, 45°), provide predictable shading patterns but may limit energy efficiency compared to dynamic tracking systems. Dynamic systems, which adjust panel angles to follow the sun’s trajectory, maximize energy output but create variable light conditions for crops.

Dupraz et al. (2011) conducted pioneering work in this area, revealing inherent trade-offs—dynamic systems enhance energy yields but may reduce crop productivity due to inconsistent light availability. These findings underscore the importance of context-specific designs that balance energy and agricultural goals.

To ensure agrivoltaic systems are viable across diverse environments, researchers test a variety of crop species with contrasting ecological needs. For example, shade-tolerant crops like lettuce (Lactuca sativa) often thrive under solar panels, as partial shading reduces heat stress and water demand.

Conversely, sun-dependent crops such as wheat (Triticum aestivum) may struggle under similar conditions due to insufficient light penetration. Amaducci et al. (2018) argue that testing crops with varying requirements allows for adaptable system designs tailored to regional climates and agronomic practices. This approach is critical for scaling agrivoltaics globally, as solutions must align with local agricultural priorities, whether water conservation in arid regions or yield optimization in temperate zones.

A key focus of these experiments is understanding species-specific responses to microclimatic changes induced by solar panels. Photovoltaic arrays alter temperature, humidity, and light distribution, creating unique growing conditions.

Weselek et al. (2019) demonstrated that crops like spinach exhibit improved water-use efficiency under panels due to reduced evaporation, while light-sensitive crops like maize experience yield declines. These microclimatic interactions highlight the need for strategic crop selection and panel placement. For instance, pairing dynamic tracking systems with shade-adapted species could mitigate productivity losses while maintaining high energy output.

The synthesis of these findings emphasizes the interdisciplinary nature of agrivoltaic research. Field experiments, as opposed to controlled lab studies, account for real-world variables such as soil heterogeneity, weather fluctuations, and farm management practices.

Dupraz et al. (2011) and Amaducci et al. (2018) collectively advocate for iterative, site-specific testing to refine agrivoltaic systems. Weselek et al. (2019) further stress that crop management strategies—such as adjusting planting schedules or selecting hybrid crop varieties—can enhance compatibility with photovoltaic infrastructure. Together, these insights advance agrivoltaics as a sustainable land-use solution, harmonizing clean energy production with resilient agriculture.

6.2 Data Collection

6.2.1 Crop Metrics

The assessment of crop performance in agrivoltaics systems or other agricultural setups requires detailed measurement and analysis of growth rates, yields, and physiological processes to understand the system’s impact on crop productivity and resource use efficiency.

• Growth Rates and Yield

Growth rates and final yields are fundamental metrics for evaluating crop performance. These are often measured using both sensor networks and manual methods. Sensor-based technologies, such as LI-COR gas analyzers, are widely used for non-invasive monitoring of photosynthesis, transpiration, and other physiological parameters. These instruments provide real-time data, enabling continuous assessment of crop responses to environmental variables.

• Destructive Sampling

Although invasive, destructive sampling remains an essential method for obtaining accurate measurements of biomass, nutrient content, and other crop parameters. This approach involves harvesting and analyzing plant tissues, which offers detailed insights into nutrient allocation, growth efficiency, and overall plant health. According to Hunt et al. (2002), destructive sampling provides precise data that complement non-invasive techniques, helping to validate sensor-derived measurements and refine crop models.

• Evapotranspiration as a Water-Use Metric

Evapotranspiration (ET) is a critical indicator of crop water use, integrating both transpiration by plants and evaporation from the soil. ET measurements are essential for understanding water dynamics in the field and optimizing irrigation strategies. Advanced techniques such as eddy covariance systems or lysimeters are commonly employed for accurate ET quantification. Eddy covariance measures fluxes of water vapor between the crop canopy and the atmosphere, providing real-time, field-scale ET estimates. Lysimeters, on the other hand, directly measure changes in soil water content. These methods align with FAO guidelines, as outlined by Allen et al. (1998), ensuring standardized and reliable water-use assessments.

6.2.2 Soil Health

Assessing soil health is critical for understanding the long-term sustainability of agricultural systems, including agrivoltaics. Key indicators such as microbial activity, organic matter content, and nutrient cycling provide valuable insights into the soil’s functionality and fertility.

• Microbial Activity

Microbial communities are vital for nutrient cycling and organic matter decomposition. Their activity is commonly assessed using phospholipid fatty acid (PLFA) analysis, a method that quantifies specific fatty acids to characterize the microbial biomass and community composition in the soil. This approach is effective in detecting shifts in microbial dynamics due to changes in land management or environmental conditions (Weil & Brady, 2017). PLFA analysis serves as a sensitive indicator of soil health, particularly in response to alterations in shading or moisture under agrivoltaics systems.

• Organic Matter and Nutrient Cycling

Soil organic matter, a key determinant of soil fertility and structure, is evaluated through wet chemistry assays. These assays measure parameters such as total organic carbon, nitrogen, and key nutrients. Nutrient cycling, which is central to maintaining soil fertility, is also monitored using similar chemical methods to understand the availability and turnover of essential nutrients like nitrogen and phosphorus (Weil & Brady, 2017).

• Standardized Methods for Agroecosystems

Standardization of methodologies is essential for generating consistent and comparable data. Anderson and Ingram (1993) provide a comprehensive framework for assessing soil health in agroecosystems. Their guidelines include protocols for evaluating microbial activity, organic matter, and nutrient dynamics, ensuring methodological rigor and reliability across studies.

 6.2.3 Microclimatic Variables

Microclimatic variables such as temperature, humidity, and photosynthetically active radiation (PAR) are critical in understanding the interactions between crops and their surrounding environment. These variables are particularly significant in systems like agrivoltaics, where the presence of solar panels modifies light availability, temperature regimes, and moisture dynamics within the crop canopy.

• Monitoring Temperature and Humidity

Temperature and humidity are monitored to assess the microenvironment surrounding the crops. Automated weather stations equipped with sensors are often deployed for continuous, real-time data collection. Handheld devices also serve as a practical alternative for spot measurements, especially in small-scale studies. These tools help determine how shading from solar panels influences diurnal and seasonal temperature fluctuations and humidity levels, both of which are crucial for crop growth and stress responses.

• Photosynthetically Active Radiation (PAR)

PAR, the range of light wavelengths utilized in photosynthesis, is another vital microclimatic variable. Monitoring PAR helps evaluate the extent of shading under agrivoltaics systems and its impact on crop photosynthetic efficiency. Sensors like Decagon EC-5 soil moisture sensors and dedicated PAR meters are commonly used for precise measurements.

• Role in Agrivoltaic Trials

Marrou et al. (2013) conducted extensive trials to validate the use of automated and handheld monitoring setups in agrivoltaics. Their research demonstrated how shading from solar panels alters the microenvironment, including reductions in peak temperature and modifications to light intensity. These changes can benefit certain crops by reducing heat stress and optimizing water use efficiency, while others may experience growth limitations due to reduced light availability.

 6.3 Statistical Analysis

Mixed-effects models, as described by Pinheiro and Bates (2000), are widely utilized in agroecological research for analyzing hierarchical data structures, such as repeated measures across multiple plots and seasons. These models effectively separate fixed effects—such as solar panel configurations and crop species—from random effects like soil variability and weather fluctuations.

Their flexibility in handling unbalanced designs makes them particularly suited for ecological studies, as emphasized by Zuur et al. (2009). For example, in agrivoltaic systems, crop yield can be modeled as a response variable influenced by solar panel type (fixed effect) and plot nested within site (random effect), while controlling for important covariates such as photosynthetically active radiation (PAR) and soil moisture.

This statistical framework enables robust inference by accounting for both environmental heterogeneity and experimental design complexities, facilitating a comprehensive understanding of interactions in complex agroecological systems (Dinesh & Pearce, 2016).

WORK PLAN

 Year 1

• Conduct literature review and finalize experimental designs.
• Set up field trials and install monitoring equipment.

Year 2

• Collect and analyze data on crop performance and microclimatic conditions.
• Present preliminary findings at conferences.

Year 3

• Conduct detailed soil health and disease pressure assessments.
• Publish initial results in peer-reviewed journals.

Year 4

• Optimize agrivoltaics designs based on cumulative findings.
• Complete thesis and disseminate results through publications and stakeholder workshops.

REFERENCES

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