According to the American Farmland Trust, the U.S. lost 2,000 acres of farmland and ranchland daily from 2001 to 2016. If thias trend continues, the U.S. will lose an area almost the size of South Carolina between 2016 and 2040. The loss of prime agricultural land could be detrimental to food security. Although numerous factors are driving this trend, solar farm construction is contributing to some agricultural land loss, but the use of agrivoltaics or dual use solar projects can help.
Is it necessary to choose between food and renewable energy production? Some solar energy developers and researchers are experimenting with agrivoltaics, simultaneously incorporating solar and agricultural production on the same plot of land. This can boost the sustainability of photovoltaic systems while mitigating fossil fuel use and climate change.
"Solar projects are commonly built on agricultural lands, which then creates the challenge of balancing food security with increasing renewable energy production," says Brittany Staie, a research intern at the National Renewable Energy Laboratory. "Agrivoltaics gives us the opportunity to explore growing food while also producing clean electricity on the same piece of land."
What Is Agrivoltaics?
Agrivoltaics are dual use solar projects that combine solar and agriculture. It can entail growing crops, locating honeybee hives, and grazing livestock at ground-mounted solar farms. In some cases, solar developers alter the layout of the solar farm by elevating the panels or allowing larger row spacing to enable livestock grazing and farm equipment access. However, such modifications can increase the construction costs of solar PV farms, so it is critical to understand how to make agrivoltaics cost-effective and practical on a larger scale.
One of the most widespread uses of agrivoltaics involves grazing sheep on solar farms. This also helps reduce the need to mow the site to prevent vegetation from shading the PV modules and usually doesn’t require modifications to the project layout. In addition, some solar developers are partnering with beekeepers to locate honeybee hives at solar farms. However, it is currently relatively rare to cultivate crops at solar farms.
The National Renewable Energy Laboratory InSPIRE Program is investigating how to make agrivoltaic systems more widespread. "Through our work, which spans multiple regions, configurations, and agricultural activities, we've seen so many initial promising results," says Jordan Macknick, NREL's lead energy-water-land analyst and principal investigator for the InSPIRE project. "Now, our challenge is to figure out how to scale up and replicate these successes."
What Are The Benefits Of Combining Agriculture And Solar Energy in Dual Use Solar Projects?
Combining agriculture and solar energy through dual-use solar projects offers innovative solutions to address community concerns while fostering economic opportunities for local farmers and enhancing soil health.
Addressing Community Concerns
Many communities express hesitance about solar farm development due to concerns about losing productive farmland and the potential negative impacts on soil quality. Integrating food production with sustainable energy through dual use solar projects can help alleviate these concerns. By demonstrating that solar farms can coexist with agricultural production can significantly boost community support for solar developments.
Economic Opportunities From Agrivoltaics
The combination of agriculture and solar energy creates new economic opportunities for local farmers, beekeepers, and ranchers. For example, sheep grazing is increasingly popular on solar farms because it reduces mowing costs and minimizes herbicide use.
Solar grazing also prevents shading of photovoltaic panels, ensuring they remain efficient while enhancing land productivity. This mutually beneficial arrangement provides financial incentives for farmers while maintaining the operational efficiency of solar installations.
Research and Best Practices in Dual Use Solar Projects
Since agrivoltaics is a relatively new concept, ongoing research is crucial to establishing best practices and making these systems cost-effective on a larger scale. Many agrivoltaic projects foster relationships with academic and research institutions to explore innovative solutions and share knowledge.
These partnerships facilitate hands-on learning opportunities focused on crop productivity, soil health, and the creation of microclimates around solar panels. By understanding how to optimize both agricultural yield and solar energy generation, these projects can set a precedent for sustainable land use.
Promoting Soil Health
Integrating agriculture with solar energy can also improve soil health. Certain crops can be cultivated under solar panels, contributing organic matter back into the soil while utilizing the shade provided by the panels to thrive. This approach can help mitigate soil erosion and enhance overall soil structure, promoting a healthier ecosystem for both farming and solar energy production.
Potential Drawbacks Of Dual Use Solar Projects
Although they can provide benefits, dual use solar projects can present several challenges that need careful consideration.
Equipment Accessibility
One of the primary concerns is the difficulty for farmers to access agricultural equipment due to the presence of photovoltaic (PV) panels and racking systems on the land. Adjustments such as elevating the panels or increasing the spacing between rows could alleviate some accessibility issues. However, these modifications can lead to higher construction costs and may require additional land, making it a less feasible option for some farmers.
Water Availability
Agricultural production often necessitates access to water for livestock and irrigation, which can be problematic in certain regions. For instance, areas with arid conditions, such as parts of the Western U.S., may not be suitable for agrivoltaics due to limited water resources. Proper management strategies must be employed to ensure that both solar energy generation and agricultural needs are met.
Crop Suitability
Solar energy systems can create shade, which affects crop growth. Therefore, selecting the right crops is crucial, as some varieties are more tolerant of shaded conditions than others. Understanding which crops can thrive in partial shade is essential for the success of dual use projects, as improper crop selection may lead to reduced agricultural yields.
Soil Compaction and Quality
The construction and maintenance of solar arrays can adversely impact the land. Machinery used during installation can compact the soil, and in some cases, topsoil may be removed, degrading soil quality and hindering agricultural productivity. Maintaining soil health is critical for the success of agrivoltaics projects.
Liability Concerns
Solar developers may face liability issues related to granting access to agricultural equipment on solar farms. The risk of damage to solar photovoltaic panels, racking systems, conduit, or inverters due to equipment usage can result in decreased energy generation and increased repair costs. Balancing agricultural access with the protection of solar infrastructure is a significant challenge that requires careful planning.
Are There Agrivoltaic Installations Already In The US?
There are numerous utility-scale solar farms that involve food production, and sheep grazing and native groundcover for pollinators have become relatively widespread. Sheep grazing is an increasingly popular way to reduce mowing costs, and numerous dual use solar projects incorporate grazing, especially across the Midwest and Eastern United States. In addition, some agrivoltaics projects involve honeybees, native pollinators, and crop production.
Some notable agrivoltaics projects in the U.S. include:
In Elizabethtown College in Pennsylvania, a solar farm provides 20% of the campus’ electricity. It features a pollinator-friendly ground cover and landscape buffers that create habitat for bees, birds, butterflies, and other small wildlife. The college has honeybee hives and uses the solar farm as a living laboratory.
At Grafton Solar in Massachusetts, a community solar farm, lettuce and squash are planted among rows of solar panels, and cattle graze part of the site. The site was developed with agrivoltaic research in mind, and UMass Amherst researchers are studying how the solar panels impact agricultural production.
In Midcoast Maine, low-bush blueberries are growing under solar panels. Researchers from the University of Maine Cooperative Extension are using the project as an educational model to study how to harvest, mow, and spray crops.
Jack’s Solar Garden with the Colorado Agrivoltaic Learning Center connects students and community members with clean energy and local food production at this 1.2-megawatt solar project. The solar panels are 2 meters above the ground, adding about 10% to the total installation cost.
The Oregon Agrivoltaic Research Facility, located at Oregon State University, explores the dual use of land for both solar energy generation and agricultural production. This innovative project focuses on growing high-value crops, such as lavender and specialty herbs, beneath solar panels. Researchers are assessing the impact of shading from the panels on crop yield and soil health, aiming to establish best practices for agrivoltaic systems.
Are There Other Types Of Dual Purpose Land Use We Could Employ In The U.S.?
An innvoative approach to dual use solar projects is creating pollinator habitat with native groundcovers and landscape buffers. In fact, pollinator habitat at solar farms could help increase agricultural productivity and crop yields on nearby farms. Although this isn't agrivoltaics, it can help promote agricultural production by boosting pollinator populations.
Using native wildflowers can reduce mowing expenses and the associated carbon emissions. Likewise, native wildflowers are usually more drought-resistant than many grasses, so they can reduce water use. Establishing a pollinator habitat is relatively easy to achieve and doesn’t require modifying the solar farm layout.
“The long-term cost over the life of the facility to maintain pollinator habitat is half or even less than the cost to establish and maintain turfgrass,” says Heidi Hartman, an Argonne National Laboratory researcher. “I’ve seen a variety of costs, and it varies job by job because of the mowing costs.”
“In the first 4 years, pollinator habitat is more expensive because the wildflower seeds are more expensive than the turfgrass seeds. Once established, native wildflowers need much less maintenance and they only need one mowing a year. They are also much more resistant to drought and soil erosion. Also, 20 years down the road, the soil underneath will be in good condition to return it to valuable cropland.”
Reducing Mowing Costs With Solar Grazing
Reducing mowing costs at solar farms by using sheep grazing is an innovative agrivoltaics application that offers several benefits. Grazing sheep can significantly cut down on the expenses associated with traditional mowing, including fuel, labor, and equipment maintenance. Sheep grazing helps maintain vegetation at manageable levels without the use of chemicals or fossil fuels, reducing the carbon footprint of the solar farm.
Collaborate with local farmers or shepherds who can provide the sheep and manage the grazing activities for this innovative approach to agrivoltaics. This can reduce the initial setup costs and leverage local expertise. Provide necessary infrastructure, such as water sources, shade, and shelter, to ensure the sheep's well-being.
Choose hardy breeds that are well-suited to the local climate and grazing conditions. Implement rotational grazing practices to allow vegetation recovery and maintain soil health. Regularly monitor the health of the vegetation and the sheep to ensure the system is functioning effectively. Adjust grazing intensity and duration based on vegetation growth and seasonal changes.
Agriculture on Solar Farms Produces Numerous Benefits
A considerable amount of farmland has been lost in the last few decades in the U.S., and this trend is likely to continue. Unfortunately, one of the many causes is solar farm development, but the use of agrivoltaics and solar farms is enabling agricultural and solar power production on the same plot of land.
Sheep grazing at solar farms is growing in popularity and is becoming somewhat widespread. Although the cultivation of crops on solar farms is relatively rare, researchers are examining ways to make it more common and cost-effective. In addition, some solar developers are using native groundcovers and landscape buffers to help promote pollinator habitat.
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