Written for the AgriSolar Clearinghouse by Ridge to Reefs staff Phal Mantha and Paul Sturm
Agricultural operations, land management, and environmental projects all have a strong need for consistent monitoring and recording of field conditions over long periods of time. Assessing local environmental conditions can be critical for timing farm operations, as well as for making important management decisions. However, due to the remote location of many farms and sites, this monitoring can prove to be a major challenge. This challenge is further compounded on sites where there is no access to grid power, Wi-Fi signal, cell service or other means of powering sensors and transmitting vital data.
In this context, the use of simple standalone photovoltaic (PV) systems in conjunction with wireless jetpacks and/or Low Power Wide Area Networks (LPWA) present a viable and cost effective solution to address some of these challenges. This brief case study highlights the use of one such system to perform real-time monitoring of environmental conditions, including soil health. In addition to monitoring, this system was also capable of controlling a Hunter PHC-1200 Wi-fi Irrigation Control System.
Fig. 1 Site plan for the Pilot Phytoremediation System installed in Kihei, Maui.
Ridge to Reefs and Sunshine Vetiver Solutions were implementing a nature-based waste-water treatment system in Kihei, Maui, Hawaii. The State of Hawai’i currently injects over 15 million gallons per day of secondary treated wastewater effluent into groundwater injection wells. In 2020, this contentious practice was ruled a violation of the Clean Water Act by the U.S. Supreme Court in the landmark case County of Maui v. Hawaiʻi Wildlife Fund. To highlight low-cost alternatives to groundwater injection, a pilot phytoremediation system was designed and constructed to determine the area required to treat and dispose of the 1.8 million gallons per day that the Kihei Wastewater Reclamation Facility currently injects. To measure this, a ⅓ acre plot of the sterile Sunshine cultivar of vetiver grass was established at the site.
Figure 2. Vetiver Grass establishment within 3 months.
There was no access to power or the internet, making system monitoring a real challenge. First a low-cost, small capacity PV system was set up, which included a single solar panel, charge controller, battery, and inverter. The electronics for this system were mounted inside a shipping container at the site, while the single solar panel was mounted on top of the container.
Next, a Verizon Mi-Fi jetpack mobile hotspot device was purchased from a local Verizon retailer. Though this service required a monthly subscription, it provided a consistent and stable internet connection, enabling the rest of the components to receive and transmit data. Furthermore, the jetpack used very little power through a USB connection and was perfectly suited for running on a small PV system plugged into the inverter.
Figure 3. Davis Instruments Vantage Pro 2 Wireless Weather Station.
To measure localized environmental conditions, including precipitation, temperature, wind speed, and solar radiation, a Davis Instruments Vantage Pro 2 wireless weather station was installed at the site. In addition to atmospheric conditions, the project required that real-time nutrient monitoring was performed within the soil profile. In order to enable this, two Terralytic soil probes were installed within the vetiver rows in different locations within the test plot. These probes are capable of recording and transmitting real-time data for important soil-health parameters, including soil moisture, salinity, nitrate, potassium, phosphorus, soil temperature, pH, respiration, and aeration, and allowed us to verify that the system was working properly and effectively treating the effluent from the wastewater treatment plant.
Figure 4. Terralytic Soil Probe and the various parameters it provides real time data on.
Finally, a Hunter PHC-1200 Wi-Fi Irrigation Control System was also installed at the site, allowing our team to wirelessly monitor and control the distribution of effluent throughout the different zones in our test plot. The Hydrawise software that controls this system allows anytime access from a smartphone or tablet with this remote monitoring, facilitating remote monitoring and management of the irrigation controls. Furthermore, the web-based monitoring was linked to local weather forecast data, including temperature, windspeed, precipitation, and other factors to automatically adjust our system to local conditions. This ensured that we were not irrigating while it was raining and maximized the evapo-transipirative potential of the system.
Figure 5. The Hunter PHC-1200 Wi-Fi Irrigation Control System that was installed at the site.
A simple and low-cost standalone PV system can be combined with off-the-shelf mobile hotspot technology and weather stations/soil probes to provide high-quality, real-time data on both atmospheric conditions and soil health. Furthermore, this type of configuration can be combined with wifi-enabled irrigation controllers, allowing farmers, landowners, and land managers to control and automate irrigation operations in a highly efficient manner, even in remote areas lacking grid power and connectivity.
All photos courtesy of Ridge to Reefs.
By Helge Biernath, Sunstall Inc.
I just attended the 2023 Solar Farm Summit, where I presented and spoke to the experts in the industry. One topic never came up: How will ESG (environmental, social, and governance) requirements from companies like Coca-Cola Now and Walmart influence agricultural photovoltaics? ESG requirements from such companies are likely to have a significant impact on agricultural photovoltaics (APV), the practice of integrating solar panels into agricultural lands.
Firstly, these companies have committed to reducing their carbon footprint and promoting sustainable practices in their operations, which will require them to procure renewable energy. APV is a form of renewable energy that can be integrated into agricultural production and help reduce the carbon footprint of these companies. Therefore, the ESG requirements of these companies may drive the adoption of APV by their suppliers and partners. And not only that: they will also require their suppliers to follow similar regimens to reduce the carbon footprint, and they will ask for strategic plans to get there and reports on the success.
Secondly, APV can offer several benefits to farmers, including providing an additional source of income, reducing water evaporation, and improving crop yield. By promoting the adoption of APV, these companies can encourage sustainable agricultural practices and support local communities. Given the ESG requirements, farmers will be asked to support the goal of carbon neutrality. It will be a challenge but also a huge opportunity through solar farming.
Finally, ESG requirements are increasingly becoming a factor in investment decisions, with investors looking for companies that prioritize sustainability and social responsibility. The adoption of APV can enhance the ESG profile of companies in the agriculture sector and help them attract more socially responsible investment.
In summary, the ESG requirements of companies like Coca-Cola and Walmart are likely to drive the adoption of APV in the agriculture sector, promoting sustainable practices, reducing carbon footprint, and improving the ESG profile of companies in the sector.
And the Oscar goes to THE FARMERS! They will be asked to help!
I feel with the solutions we have seen over the last days at the Solar Farm Summit, the agriculture and solar community is ready to support ESG goals.
All photos courtesy of Sunstall, Inc.
by Emily Griffith of Renewable NorthWest
Renewable Northwest and a small workgroup are preparing an update to the 2019 report, Dual-Use Solar in the Pacific Northwest: A Way Forward, in response to the changing landscape of agrivoltaics (also referred to as dual-use solar) in the region. This blog will explain the need for a fresh look at dual-use in the Pacific Northwest and describe some of the themes important to the conversation.
Why Do We Need to Revisit Dual-use Solar?
The Biden Administration recently set a goal of reaching 100% carbon-free electricity by 2035. Many states have similar requirements of reaching net-zero GHG emissions. To reach these targets, extensive buildout of solar energy will be a cornerstone of the evolving energy grid. Dual-use solar allows farmers to use their land both as farmland and as a site to generate electricity (and additional income).
In Renewable Northwest’s 2019 report, staff explored the potential and practicality of dual-use solar by looking at advantages and disadvantages, policies, project examples, and best practices. Given the increased attention agrivoltaics has received recently, including federal research investments and policy changes, it’s time to revisit the report. The updated report (to be completed in spring 2023) will explore recent updates in agrivoltaics. Here is what you can expect:
What Has Not Changed?
The conversation around dual-use in the Pacific Northwest is still in early stages. To date, the region still does not have many dual-use projects, but some solar and pollinator projects do exist. For example, Pine Gate Renewables’ Eagle Point Solar is a 13-MW solar and pollinator project located on 41 acres in Medford, Oregon. Previously, the land was used for dairy grazing. Now, the site contains a diverse seed mix of pollinating flowers with over 30 types of native flowers and grasses. Old Sol Apiaries is a business based in southern Oregon that provides bees for honey makers and commercial pollinators. Bees forage on native pollinator plants under Pine Gate’s panels. They also provide bees at other solar-pollinator locations, such as a 73-acre project in Clackamas County, Oregon.
There are a few reasons why dual-use is still not as widely used in this region as it is in others. For instance, there are still policy barriers. In fact, every year there are regular efforts pushing back against solar development by legislators in the Northwest. For example, in Oregon, the Land Conservation and Development Commission issued a rulemaking in 2019 limiting the amount of land to 12 acres that a farmer could use for a solar project located on high-value farmland. However, there was potential for counties to issue ordinances that could increase to 20 acres for dual-use projects. The difficulty with this rulemaking was that it sunsetted after two and a half years, and counties did not have much of a chance to develop an ordinance before the sunset. Additionally, counties in Washington state are continuing to develop ordinances that limit renewable energy development, including potential dual-use projects.
Agrivoltaics continues to be a challenging environment. The idea of agrivoltaics originated in Europe and is just gaining momentum in the U.S. A recent article by Jeff Turrentine at the National Resources Defense Council (NRDC) states that in a number of Asian and European countries, agrivoltaics has gained much more ground. For instance, in Japan, there are 2,000 agrivoltaic installations, whereas in the U.S., there are less than 50 accounted for. The U.S. is not as far along as others for a few reasons:
- There are significant up-front costs and barriers to entry.
- Research on large-scale solar with crops and grazing is still considered to be in early stages.
- There is limited transmission for projects to connect to. Projects most often need to be located near the electricity load (demand).
- Many farmers are still uneasy about the idea of combining solar and agriculture.
What Has Changed?
While there still are not many dual-use projects in the Northwest, we have seen more interest in the idea of advancing dual-use. New research continues to be published on the advances in dual-use technology and solar-crop compatibility. Some recent studies even suggest that, under the protection of solar panels, certain crops may grow stronger and longer that may otherwise succumb to higher temperatures more readily.
Another interesting Oregon State University study found that there is a symbiotic relationship between solar panels and the crops that grow beneath them. Crops exposed to increased levels of sunlight require more water. With solar panels providing shade and cooler temperatures, less water is lost to evaporation and the plants require less water from irrigation. But perhaps the more interesting finding is that the panels were found to perform better with the crops growing beneath them. The crops beneath the panels contributed to keeping the local environment cooler. With cooler temperatures, the panels operate more efficiently, generating about 10% more electricity than panels installed over gravel.
There are additional efforts and funding being devoted to studying and implementing dual-use projects. Last December, DOE announced $8 million in funding for projects that integrate solar energy production with farming. An energy.gov article states that the funding is intended to reduce barriers to both community and utility-scale solar energy deployment while also maximizing benefits to farmers and local communities. The six states (and the District of Columbia) selected for funding are not located in the Pacific Northwest region. However, the studies will likely produce valuable knowledge that can be integrated here, as well. Some of the topics pertain to socioeconomics, technical aspects, outreach strategies, deployment resources, sustainability, and markets in rural North America.
Additionally, in 2021, the USDA awarded the University of Illinois $10 million to determine the types of crops that are best suited to pair with solar. The research sites include Illinois, Arizona, and Colorado.
With already cost-competitive solar bolstered by the recent passage of the Inflation Reduction Act, solar development is expected to increase dramatically. Hopefully, this means we will see more dual-use projects. And, the increased interest in studying agrivoltaics from the DOE and USDA could perhaps be a sign federal aid is on the way for farmers interested in agrivoltaics. Right now, there is a real need for additional mechanisms and incentives for those interested in pursuing dual-use projects in particular.
How Is the Region Reacting to the Prospect of Dual-use?
While dual-use solar may not be a silverbullet solution to siting solar on farmland, it does offer a tool of flexibility for farmers. This tool can provide additional income that keeps farmers farming and keeps farmland as farmland. The previously mentioned NRDC article states that many people are optimistic about the idea of expanding agrivoltaic facilities with options to sustain farming, potential to bring in new farmers, and stabilize land for crops that could otherwise go to more permanent types of development.
There are still many other areas of interest that updated report may investigate. For instance, we need to know: Four years later, where are we? Have many projects been implemented since 2019 and how are they doing? Are projects happening practically? What are the dos and don’ts of building a dual-use project? What are the many other studies saying? What are the farmers concerned about?
The U.S. is looking to develop about five times the solar we have to date over the next 10 years, and that solar will require land (at least for its useful life). But new solar buildouts don’t have to result in conflicts. Many think agrivoltaics is a key solution, especially when it comes to avoiding potential conflicts between energy and food production. And with more research and funding being devoted to the idea, dual-use is becoming less of a research question and more of a reality.
If you would like to be notified when the final and updated dual-use report is available, please contact Emily at firstname.lastname@example.org
By Brigitta Banki and Kate Lundquist, Stracker Solar
Farmers and ranchers all over the United States are increasingly interested in taking part in solar energy initiatives. Agrivoltaics can mean not only cleaner energy, but also savings on operational expenses, as well as the opportunity to develop a secondary income stream by selling the power to utility companies or to offtakers directly through community solar programs.
The available options for agrisolar are greenhouse roof-mounted solar, fixed ground-mounted systems, and elevated solar trackers. Let’s look at the differences, pros, and cons of each type.
Greenhouse Roof-mounted Agrisolar
Fixed solar panels mounted on the roofs of greenhouses are generally the least efficient of all agrivoltaic solar solutions and come with limitations based on the location and roof direction of the structure. The ideal location for solar panels in the U.S. is facing south, with a secondary option of west-facing roof exposure.
In recent years, the popularity of greenhouse roof-mounted solar has grown since those buildings are generally built with a southern exposure. This option has the unexpected drawback of having a markedly negative impact on yields and energy output. One study from the University of Arizona found that when half the greenhouse roof was covered with conventional solar panels, crop output was reduced by 64% and panel productivity was 84% lower.
Fixed Ground-mounted Solar
Low ground-mounted solar panels are a slightly more efficient option. Available in different heights, the panels are installed on rows of metal racking: typical low ground-mounts are at 1 to 3 feet high, while high ground-mounts start around 6 to 7 feet high. A ground-mounted solar system has the advantage of relatively low installation costs, but the intricate support structure can greatly limit access and agricultural use of the land beneath and between the solar panels.
Only certain low-growing crops that are generally hand-cultivated and harvested (such as lettuce, chard, beets, spinach, and tomatoes) are easily grown beneath fixed solar arrays. Access for farm equipment, however, is reduced to the area between rows and only if the installation is designed accordingly. The space around and under a ground-mounted system can be used as grazing area for livestock, as well. However, grazing is only recommended for smaller animals like sheep and goats, in order to avoid damage to the panels or the supporting structure.
The advantages of fixed ground-mounted systems come from use with low-growing and shade benefitting crops. Benefits are particularly pronounced in regions with hot, dry climates like the American Southwest. Studies have shown that shading from solar panels can maintain and even increase crop yield while reducing water use, an especially welcome option for farms in the areas of the United States where drought is common and water rights are changing.
Elevated Solar Trackers
Elevated tracking solar is the newest and arguably most efficient solution for agrisolar due to the unique tracking design and elevated build. Dual-axis solar trackers have a drive core that moves the arrays along both east-west and north-south axes, maximizing the amount of time the panels receive direct sun exposure. Thanks to the ability to follow the sun’s exact location throughout the day, dual-axis solar trackers provide an increase in energy generation of 50% or more compared to fixed solar power systems with the same number and type of panels.
With maximized solar power production per panel, a small footprint, robust structure, and continued full use of the grounds, pole-mounted dual-axis solar trackers are also the most adaptable solar energy harvesting option for agrivoltaics. Single pole-elevated solar trackers, like Stracker Solar’s elevated dual-axis solar trackers, maintain full use of the land below the solar installation. These high-efficiency trackers feature a 13.6-foot minimum ground clearance with a mounting base of a mere 5 square feet, allowing easy access for every type of farm equipment. Furthermore, since it takes fewer of these high-efficiency solar trackers to generate the desired amount of energy compared to their fixed counterparts, a smaller area is sufficient for the solar installation. The Stracker elevated dual-axis solar trackers deliver up to 70% more energy production compared to fixed solar power systems of the same size. They provide access to solar energy generation while avoiding the financial drawbacks associated with compromising land use or crop yield.
Elevated solar trackers are ideal for agricultural use but all are not created equal. Given the current options for investing in agrisolar, pole-elevated dual-axis solar trackers provide the most flexibility and highest rates of energy generation currently available. These giant mechanical sunflowers maintain full use of the ground underneath the system by accommodating crops and livestock of all types and sizes, including wheat, corn, and cows. Large farm machinery for soil cultivation, crop harvesting, and processing can operate under the panels. Elevated solar trackers make installation on uneven, hilly, or difficult sites a possibility, as well.
However, elevated dual-axis solar trackers vary greatly in design, materials, performance, and durability.
Some dual-axis solar trackers are built using cheaper, and less reliable, aluminum components to reduce costs, while others are built entirely of structural steel. The environmental conditions an installation needs to withstand for 30 or more years while maintaining optimum performance requires a high degree of stability and material strength, both of which are qualities of structural steel.
Material tolerance is another key aspect of solar tracking design that leaves no room for compromise. The build quality of solar trackers is determined by the way different parts of the drive core, as well as the bolts and plates are connected at each step of the way, down to the foundation. With loose connections and weak fittings that could be the result of weaker materials, a tracker could lose its ability to track accurately and perform safely over time.
The most complex, vulnerable, and expensive component of dual-axis solar trackers is the drive core mechanism. Some manufacturers use hydraulic motors and linear actuators, both of which can be the source of a variety of problems. A typical example is hydraulic tank leakage, which makes the tracker stop moving until replaced. These drive systems are often built of galvanized steel and aluminum, though they have plastic components as well, and they don’t meet the structural code requirements of many states. Slew drives are a more durable solution, yet fewer manufacturers use them because they are more expensive and require a higher level of precision to install. Stracker Solar’s elevated solar trackers are built entirely of structural steel and each unit uses two robust electrically driven slew drives for decades of strong performance.
High-quality materials, reliable design, and precision in assembly make a huge difference to the performance and durability of dual-axis solar trackers. But one cannot inspect all the screws and bolts before making a purchase decision. How can one have confidence that the chosen elevated solar tracker will work well in the long run?
That’s where structural warranty comes into the picture.
When calculating return on investment, one needs to consider the accompanying product warranty very carefully. The return on a system with a 10-year warranty is quite different from the return on a system with a 30-year warranty. Since after a 10-year warranty expires, farmers and ranchers will be responsible for the cost of troubleshooting and repairing any structural defects, which can significantly reduce their return over a longer period. Especially when we factor in that manufacturers who only offer a 10-year warranty are likely doing so because they know that their system failure rate beyond 10 years is too high. Stracker Solar is unique in offering a 30-year structural warranty on their elevated dual-axis solar trackers.
Researching available elevated dual-axis solar trackers and other applicable PV systems thoroughly and comparing key features, as well as considering power production data and costs, are very important steps before deciding on an agrivoltaic solution.
As the United States moves towards a zero-carbon future, farms and ranches have the opportunity to become primary sites for community and utility scale solar installations, increasingly supported by funds from the USDA. Elevated solar trackers provide an attractive option for agricultural operations looking towards solar to reduce operating expenses and/or establish a reliable secondary revenue stream.
All photos courtesy of Stracker Solar
By Tyler Swanson and Quin Karhoff
The Bock Agricultural Law and Policy Program at the University of Illinois, Urbana Champaign is conducting a study supported by the National Renewable Energy Laboratory on the economics of solar grazing. Our research goal is to determine the structure of a solar grazing business, the cost associated with entering the solar grazing market, and a general range of profits a solar grazer can expect to earn in a given year. With this data, we aim to create a free, customizable budget tool that prospective solar grazers can use to gain a better understanding of the cost of entering the market and the revenues they can generate over time.
To accomplish our research goals, we would greatly appreciate you taking a few minutes to complete the survey linked below about your solar grazing operation. Be assured that your identity will be kept confidential.
Further, we understand that your time has value. If you include your email address at the end of the survey, we will send you a $5 Amazon gift card to compensate you for your participation.
Thank you for your assistance and we hope that the findings of our study will be beneficial to your operation. If you have any questions, please reach out to Tyler Swanson at email@example.com
By David McFeeters-Krone, RUTE Foundation Systems, Inc.
Solar development is exploding around the country. The Inflation Reduction Act incentives have exacerbated this trend such that the next 10 years will lead to solar developments on over 2 million acres of land. This extreme growth for renewable energy will put a like amount of pressure on the best solar lands. However, as shown by an Oregon State University study, most of the prime, flat land near load is already in use growing food or for ranching. Agrivoltaics is the answer to the food versus energy dilemma. Ranching holds particular promise, as partial shade has been shown to benefit forage, especially in arid regions.
In an effort to solve this problem, RUTE’s SunTracker agrivoltaic solution was selected as one of the 20 semi-finalists in NREL’s American-Made Solar Prize Round 6. SunTracker plans to use the $50,000 prize to further refine its cattle-grade, high-clearance solution and continue its component certifications at the Oregon Manufacturing Innovation Center, in Scappoose. One of the reasons RUTE was selected for this award is its focus on ranching. Rangeland, particularly for cattle, is generally more available than farmland, but cattle-grade solutions are in short supply or not cost-competitive.
The solution differs from conventional solar with its cable-stayed poles and vertical, single-axis trackers. This design offers height at less cost and less ground disturbance, making it well-suited for ranching. Initial calculations suggest a meaningful reduction of steel use, akin to the reduction of steel in a cable-stayed bridge. Work under this award and other ongoing tests will compare SunTracker’s use of metal, labor, and site prep to create an apples-to-apples comparison with today’s Horizontal Single Access Trackers (HSAT) and reinforced solutions to determine which structure is optimal in different environments.
In addition to these tests, RUTE has plans to install its first set of trackers on a Grant County, Oregon ranch in 2023. The installation—known as the Bear Valley Solar Pasture—will be complete by summer, and RUTE is looking forward to seeing their technology at work on America’s farmland. The hope is that SUNTRACKER’s high-clearance solar will enhance rural economies by no longer forcing a Faustian choice between lucrative solar leases and local jobs.
All photos courtesy of RUTE Foundation Systems, Inc.
By Jessica Guarino and Tyler Swanson
The U.S. agrivoltaics industry continues to grow as the desire to pair solar energy production land uses with pollinator habitats, livestock grazing, and crop production increases. However, while the excitement around agrivoltaics in all its forms blazes a new trail for what solar energy land use can look like, eager landowners and developers face a daunting challenge: state laws and local zoning ordinances that have not considered the possibility that agricultural and solar energy production could feasibly be located on the same tract of land.
Through Agrivoltaics in Illinois: A Regulatory and Policy Guide, researchers at the University of Illinois Urbana-Champaign’s Bock Agricultural Law & Policy Program analyze both the state and local laws that will impact agrivoltaic development in Illinois. The guide pays particular attention to county zoning ordinances, each of which define solar energy, and set the requirements necessary to develop it, in their own unique way. Agrivoltaics in Illinois allows landowners and potential solar developers to easily understand the requirements to build solar in their county and may also point developers towards counties where solar energy development faces a lower burden from the zoning board. Further, developers can read through the specific definitions that a county has for solar energy, which may have an impact on the development of agrivoltaics. For example, in many counties, a solar farm is the principal use for the land on which it is located, which could have negative implications for a landowner wishing to practice agrivoltaics and retain the tax benefits associated with land being classified as an agricultural use. Meanwhile, other counties state in their zoning ordinances that a solar installation under a specified acreage is considered a “solar garden” and thus is classified as either an accessory or special use of the land.
Agrivoltaics in Illinois: A Regulatory and Policy Guide, while focused on analyzing the state laws and local zoning ordinances of Illinois, aims to inform all landowners, farmers, and solar energy developers of the types of laws and ordinances that should be taken under consideration when exploring the deployment of an agrivoltaic system. This guide is also a resource for state and local policymakers seeking to understand what impacts existing policies may have on the development of agrivoltaics. For example, the Renewable Energy Facilities Agricultural Impact Mitigation Act is a state law requiring a deconstruction plan for wind and solar energy facilities when they reach their end of life that also provides assurances to the landowners that the land will be restored for agricultural use, which will impact agrivoltaic installations. Additionally, a local official could review the numerous figures and tables in the guide to understand what solar energy requirements are most common, as definitions and requirements for solar energy facilities vary by location.
As the agrivoltaics industry grows, it will become increasingly important to understand the regulatory framework in which it will exist. Many current zoning ordinances consider solar energy a threat to agriculture and regulate the industry accordingly, which may inhibit the ability of eager farmers and solar developers to deploy the practice. Likewise, state governments have the power to influence the development of agrivoltaics through laws such as the Renewable Energy Facilities Agricultural Impact Mitigation Act. With the legal analysis presented in this policy guide, the authors hope that it will be used by stakeholders to foster informed agrivoltaic regulations and deployment of the practice.
Photos: AgriSolar Clearinghouse
By Asaf Maman and Avi Elkayam, Trigo Solar
Declining precipitation levels and the associated reduction in arable land can negatively impact rural communities and pose a threat to food security. While utility-scale solar projects reduce greenhouse gas emissions, they can also encroach on arable lands and reduce the yield of rainfed crops. Wheat, barley, soy, corn, and other grains are cultivated in rainfed fields that are vital to food security. As precipitation levels decline and desertification spreads, arable land and farms that produce these crops are in peril.
As solar energy is employed in the conversion from fossil fuels to renewable energy, hundreds of thousands of square miles of land will include solar development. According to the National Renewable Energy Laboratory, there will be roughly 22,000 square miles of solar in the U.S. by 2035i. It is important to understand that the actual land for solar development must be adjacent to grid or to power demand centers. The growing competition between farming, suburban development, and solar development highlights the potential for agrivoltaics.
Agri-PV is a solution to this issue. It can significantly improve the cultivation of staple foods that substantially affect global food security by cracking the code and untying the water-land knot. By increasing the amount of water available for rainfed crops, we can increase the amount of arable land and avail a portion of it for sustainable solar development.
In a series of field-controlled winter wheat experiments, Trigo has discovered an almost linear correlation between the amount of water supplied to cultivated area and the quantity of stem biomass and nutritional value. Based on these findings, Trigo designed an east-west solar array formation and solar table structure to both collect and regulate rainwater for redistribution into a cultivated row below. By increasing the rain capture area from both structures, enclosing, and effectively directing the rain, we managed to control the amount of water and increase it, countering the effects of declining precipitation over years.
North-south solar array over winter wheat. Photo: Trigo Solar
Design schematic. Source: Trigo Solar
This design is focused on economic and efficient deployment of solar arrays that improve rain collection and redistribute water to boost crops growth, counter drought effects, and revive agricultural operations.
Rainwater catchment design schedmatic. Source: Trigo Solar
Benefits to this design include:
- Maintaining the same yields from smaller cultivated surface area requires more limited farming operations and lower expenses, which can increase farm profitability.
- Capturing more water and channeling it smartly reduces the risk of drought and the associated annual volatility and provides the farm with a drought shield.
- Increased ground wetness, root growth, and wind shield from the solar rows reduces the erosion and carry away of the upper soil layer, which create irreversible damage to farms.
- Preserved land under the Trigo structure can be used for future land reserve and land rotation.
- The steady income from solar power generation can support farm economics and mitigate farming financial risks.
- The availability of cheap, local, green power can further support many of the farm operations expected to undergo electrification in the coming decade.
- The existence of a water-distribution and cheap-power system changes the economics of farming, potentially allowing the cultivation of second seasonal crop during the dry season.
These benefits have the potential to create more win-win opportunities for effective cooperation between the agricultural and sustainable energy sectors.
Trigo will continue its experiments to validate the benefits for major U.S. staple crops at U.S. farms to share the knowledge and promote sustainable mass Agri-PV development.
By Stephanie Hince, AES
Although Grafton, Massachusetts, is just an hour west of Boston, life there is very different. Grafton is a friendly country town with a lovely historical feel. It has been a farming community for centuries, where thriving cotton, grist, and paper mills once dotted the landscape.
Whereas the Quinsigamond River once powered numerous mills, a newly constructed solar farm owned by AES is incorporating two Grafton traditions: clean energy and agricultural production. Let’s explore how our solar project brings together key stakeholders to help protect farmland in Grafton and beyond.
Grafton Solar’s On-site Agricultural Production
This solar installation is located on Knowlton Farm, a family farm operating for over 150 years. Instead of merely leasing fallow farmland for the project, the solar farm was designed with on-site agricultural production and research in mind from the start.
Grafton Solar is a 2-megawatt community solar farm with a 1.4-megawatt battery energy storage system. Many stakeholders have come together with a shared vision of clean energy, food production, and learning, which is making this endeavor a success.
Our current and prospective project partners include the U.S. Department of Energy, Massachusetts Department of Energy Resources, Massachusetts Department of Agricultural Resources, UMass Amherst, American Farmland Trust, and Cornell University. In December 2020, AES acquired the Grafton Solar project from BlueWave.
What Made This Solar Farm Unique from Day 1
An agricultural plan was created early in the design phase as a collaboration between Paul Knowlton, a fifth-generation farmer and current operator of Knowlton Farms, Iain Ward of Solar Agricultural Services, and BlueWave Solar. Today, that plan has come to fruition. With a keen eye, passersby will notice something very different at our project site.
Borrego, the construction contractor, elevated the solar modules to a height of 8 to 14 feet and created large inter-row spacing to allow cattle grazing and access for farm equipment. The agricultural integration component of the project began last May with the planting of squash and lettuce, as well as cattle grazing.
There is still much to be learned. Solar developers and farmers need a greater understanding of how to make widespread use of agrivoltaics cost-effective and practical. Thus, Grafton Solar provides opportunities to advance its application on other project sites and by other solar developers across the U.S.
Grafton Solar is Now a Living Laboratory
We intentionally reserved a section of the project area for new and existing research partnerships – Grafton Solar is an official hub of activity for learning about agrivoltaics. Research partners, UMass Amherst and the American Farmland Trust, are working to establish site trials to assess crop productivity, soil health, and micro-climatic conditions, thanks to a grant from the U.S. Department of Energy Solar Energy Technology Office (SETO). Once available, research information will be made publicly available so that others in the solar and agricultural industries can learn and benefit from their findings.
Solar Incentives Helped Make This Innovative Project Possible
In Massachusetts, revenue for solar projects is provided through the SMART program, which starts with a fixed compensation rate for projects. A project can obtain different adders based on project attributes, which increases the rate and therefore the benefits to the project developer and landowner. Some of these adders include making a project a community solar farm, adding battery storage, or having a dual-use agricultural component. Grafton Solar does all three.
Community solar projects expand access to renewable energy and allow subscribers like households, businesses, educational institutions, municipalities, and others to experience the same benefits of solar power without having to install a solar array on their own property. Battery storage helps to mitigate the intermittent nature of solar energy by storing solar energy when production is high and electricity demand is low and promotes reliable, carbon-free power by making solar energy available when utility companies need it most. Thus, it reduces the need to use more polluting power plants when power demand is high.
Grafton Solar is built around the community solar model, incorporates battery storage, and is supporting a legacy of agricultural production at Knowlton Farm – a win-win-win. By leveraging Massachusetts’ innovative state-level solar incentives (which includes the only rate-adder for agrivoltaics in the U.S.), Grafton Solar is delivering multiple co-benefits to the community and showcasing that solar projects can do much more than produce power on site.
Protecting Farmland When Developing Solar Energy Projects
Grafton Solar is AES’ first agrivoltaic site in the Northeast and is consistent with our vision to provide the smarter, greener energy solutions the world needs. According to a report by the American Farmland Trust, the U.S. lost or compromised 2,000 acres of farmland and ranchland every day from 2001 to 2016.
If this trend continues, an area nearly the size of South Carolina will be lost between 2016 and 2040, which could be detrimental to food security. Many farmers across the U.S., like Paul Knowlton, are looking for new revenue streams and ways to keep family farms operating for future generations. In addition to producing food, family farms are also about preserving a way of life.
At AES, we understand the importance of protecting farmland when integrating renewable energy projects into the landscape. Solar energy development and farm viability can go hand-in-hand when taking a thoughtful, dual-use approach.
Using Partnerships to Maximize Opportunities
We understand the importance of land and are actively working to create synergies between renewable energy development and agricultural land use. In addition to successfully co-locating crop growth and grazing at Grafton Solar, we have implemented active sheep grazing on thousands of acres of land at utility-scale solar sites, and we are participating in research partnerships in various regions across the U.S. to better understand how we can harvest clean energy and food from the same land.
We know that the success of our company is only as strong as the partnerships within the communities where we operate, so we develop, build, and manage projects that maximize value to a variety of stakeholders. Ultimately, we need both clean energy and productive farmland, not just one or the other.
Grafton Solar provides an excellent opportunity to collaborate with the research community and the Knowlton family to further our understanding of how to make agrivoltaics practical and more widespread. The project symbolizes preserving a way of life that spans many generations while embracing innovative clean energy technologies that promote food security, reliable energy, and a cleaner environment.