Tag Archive for: soil health

Case Study: Oregon Agrivoltaic Research Facility

Cantaloupe melons growing between rows of solar panels. 

By Anna Richmond-Mueller, NCAT Energy Analyst

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Just south of Portland, Oregon, researchers with Oregon State University (OSU) are putting agrisolar principles to the test at the Oregon Agrivoltaic Research Facility. The site is located at the Noth Willamette Research and Extension Center (NWREC) and serves as host to OSU’s ongoing agrivoltaic research under the leadership of Dr. Chad Higgins. The numerous studies conducted on the site will contribute to advancements in multiple fields, including plant physiology, water usage, and soil health, all while producing power for Oregon citizens through a community solar program.  

While agrivoltaics research has picked up in recent years, a large number of the sites being studied were not originally built with agrisolar pursuits in mind. Although it’s entirely possible to successfully integrate agricultural practices into an existing solar array, using only these sites for research lessens the opportunity to discover agrivoltaic’s full potential. With the Oregon Agrivoltaic Research Facility, Dr. Higgins and OSU flipped the narrative by instead asking: what if a solar site was designed to maximize agricultural production?  

The OSU team felt it was important to approach the project from the perspective of a farmer looking to add panels into their current operations. With that goal in mind, the decision was made to design an array that wouldn’t necessitate the purchase of specialized farming equipment capable of working amongst the panels. Instead, they used NWREC’s current tractor to determine how far apart the bifacial panels needed to be spaced and chose a racking system that can tilt to a vertical position on command.  

A row of dry farmed crops between solar panels. 

Once again approaching the project as a farmer might, Dr. Higgins and his team chose to fund the project through loans, investors, and grants rather than having the university entirely foot the bill. The team partnered with Oregon Clean Power Cooperative (OCPC), who financed the project and maintain ownership over the site. OSU contributed about 5% of the necessary funds, and OCPC’s community investment model provided the framework for local investors to contribute as well. The project also received grants from both Portland General Electric and the Roundhouse Foundation, which provided funding for on-site NWREC staff, research, materials, and construction costs. OSU anticipates the project will pay for itself in about 10 years.  

In addition to providing space for agrisolar research, the site also serves as a community solar operation with Oregon Clean Power Cooperative. OCPC was heavily involved in the project from the beginning, working with Dr. Higgins to design the system and purchase the equipment in the midst of a supply chain crisis during the pandemic. Thanks to the dedication of both parties, construction on the 5-acre, 320-kW site wrapped up in the fall of 2022, and it began producing power the following April. The site is OCPC’s first community solar project for Portland General Electric customers. Currently, OSU buys some of the power from the array, and the remaining is purchased by a local church, synagogue, and area residents, including low-income households who receive the power at a 50% discount. The partnership between OCPC and OSU has been so successful that OCPC is in the process of developing two more sites for OSU’s agrivoltaic research in the state.

Melon crop area being monitored for detailed data collection. 

Although the Oregon Agrivoltaic Research Facility is only in its first year of operation, extensive studies are already underway onsite. By the end of fall 2023, a study on soil compaction from installation will be complete, as well as an investigation into soil health in bare ground versus agrivoltaic spaces. OSU is also investing in long-term research, with a 20-year study on pollinators beginning in fall 2023. More extensive soil-quality projects will also start in the fall, looking to determine how an agrisolar system impacts soil health markers over 20 or more years. Sheep will graze on the site for part of the year, allowing for research on seasonal forage and sheep nutrition.  

Dr. Chad Higgins and Follow the Sun tour attendees behind Argonne National Lab’s wildlife monitoring camera. 

Nestled in the center of the array is a grassy row with a camera set at one end, seemingly at odds with the rows of plants surrounding it. This unassuming row is actually the location of two important studies, one focused on wildlife and the other on grass growth as a proxy for crop productivity. Argonne National Laboratory monitors the camera for wildlife that wander into the array, concentrating specifically on observing how the bird population interacts with the solar array. The grass is just one of several plots around the world included in an ongoing study by the United Nations, which is dedicated to predicting how certain crops will grow in a given environment. NWREC is home to another one of these plots, located outside of the array, and OSU team will analyze how the two onsite plots compare. This will give them insight into how a number of crops are likely to grow within the array without having to actually cultivate each plant.  

In September 2023, the AgriSolar Clearinghouse’s Follow the Sun tour had the opportunity to join Dr. Higgins in Oregon and see the OSU team’s crop research in action. The researchers chose to grow their crops using a technique called “dry farming,” which relies on soil moisture and rainfall to water the plants rather than irrigation. Agrivoltaics pairs particularly well with dry farming because the shade from the solar panels significantly reduces soil moisture loss. Several varieties of squash, tomatoes, melons, hemp, and hydrangeas were successfully growing between the panels, and plans to add blueberries in the coming months were on the docket, as well. More than 75 people signed up to attend the tour and had the opportunity to listen to Dr. Higgins discuss the research facility, scalability of the project, financial considerations, and initial observations of the plants growing within the array.  

The Oregon Agrivoltaic Research Facility’s commitment to embracing dual-use agriculture is truly inspiring. In addition to the research already in progress, there is an entire row of panels dedicated to experiential learning, the development of lesson plans, and opportunities for students. OSU’s clear investment in both current and future leaders in the agrisolar world leaves little doubt that the site will become a major contributor to the ever-growing body of agrivoltaic knowledge. 

Hemp plants (left) and delicata squash (right) growing within the array. 

Photo credit: NCAT

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Harvest the Sun — Twice

Vines growing among solar arrays. Photo: NCAT

By Brian Naughton, Co-Founder Circle Two, LLC. This article was first published in the NM Healthy Soil blog.

The sun provides abundant energy here in New Mexico, something I’ve appreciated professionally and personally since moving here ten years ago to work on renewable energy. The sun can also be a bit much at times as seen in my rather disappointing tomato patch this year. I’ve always enjoyed gardening as a hobby, but a few years ago I decided to step things up a bit by volunteering at the Rio Grande Community Farm located on the Los Poblanos Open Space in the North Valley of Albuquerque. I’ve learned so much from the community that gathers and works there about every aspect of growing food from soil health, irrigation methods, tools from small to big, and climate-controlled greenhouses to the changing climate of the open field.

One of my first days volunteering at the farm I noticed a stack of solar panels in the barn and began to brainstorm ways my renewable energy background and interest in growing food might work together. In the course of my research I came across the term agrisolar. Agrisolar, or agrivoltaics as it is sometimes called, is simply the co-location of solar power production with appropriate agricultural land use. This definition comes from the National Center for Appropriate Technology (NCAT), hosts of the AgriSolar Clearinghouse, a website for all stakeholders who are interested in finding trusted agrisolar information, funding sources, events, and more. 

As I’ve learned, there are multiple potential benefits of pairing solar and agriculture. As interest in both renewable energy and sustainable agriculture grows, agrisolar has the potential to meet both needs. The benefits include producing food, conserving ecosystems, creating renewable energy, increasing pollinator habitat, and maximizing farm revenue. In our arid Southwest landscape, researchers at the University of Arizona have found the microenvironment among the solar panels can increase humidity, decrease daytime temperatures, and increase nighttime temperatures, all of which can increase the efficiency of crop production and solar electricity generation in a symbiotic relationship.

Tomatoes growing in an agrivoltaic setting. Photo: NCAT

I find the broader connections between energy and food quite interesting and important. Sunlight is the primary energy source that keeps our living ecosystem, and our human gizmos, moving. Plants absorb the daily flows of sunlight to convert carbon dioxide in the air into biomass above and below ground. Our human systems largely do the opposite, combusting stocks of solar energy in the form of fossil fuels in the ground and turning them into carbon dioxide in the air, with all the resulting impacts we’ve come to know too well. Our domesticated crops turn out, perhaps unsurprisingly, to be a bit of a mix of energy sources.

Researchers at the University of Michigan have compiled data from multiple sources to produce some eye-opening infographics on energy use in the US food system. The biggest takeaway for me is that on average it requires 14 times the energy inputs for each calorie we consume, and the majority of that input is still fossil fuels. Perhaps agrisolar projects can help shift that statistic towards something more sustainable, but there are some knowledge gaps about how best to deploy this technology.

Agrisolar in New Mexico

One of the six soil health principles promoted by New Mexico Healthy Soil and others is to know your context. This applies equally well to agrisolar projects and the need for location-specific knowledge. While some agrisolar knowledge and practice is universal, much of it is location-specific. Fortunately, there are a few nascent efforts in New Mexico beginning to explore agrisolar applications and develop best practices for our state. I’ve chosen a few to highlight that I’m aware of, but I’m sure there are many more people and organizations that are experimenting with this approach that I have not yet learned of. 

New Mexico State University

Researchers at New Mexico State University just completed their first year investigating New Mexico green chile production under partial agrivoltaics shading at the Leyendecker Plant Science Research Center near Las Cruces. Drs. Marisa Thompson, Stephanie Walker, Olga Lavrova, and Israel Joukhadar lead the project that is supported by the New Mexico Department of Agriculture’s Specialty Crop Block Grant program. Mariela Estrada is a graduate student on the project helping to coordinate the field trial and gather data, which is currently being analyzed. The project is exploring the effects of integrating solar panels into vegetable production fields, with a particular focus on the impact on disease, plant growth, and overall yield. This innovative integration of technology into agricultural fields has the potential to offer dual benefit to New Mexico producers, protecting their crops from the region’s hot and arid climate while simultaneously generating additional income through renewable energy production. The researchers are considering additional crops they could study in the coming years.

Chiles growing on an agrisolar research site at New Mexico State University. Photo: Israel Joukhadar

USDA Agricultural Research Service

Another agrivoltaics research project in the Las Cruces area is being led by the USDA’s Agricultural Research Service. Brandon Bestelmeyer from the Range Management Research location and Derek Whitelock from the Southwest Cotton Ginning Research Laboratory are collaborating on a project titled “Sustainable Multi-functional Agricultural and Energy Systems for Arid Environments.” The project aims to develop optimized agrivoltaic designs for rangeland, crops, and processing facilities and to build accompanying decision support tools including economic and life-cycle assessments so farmers and ranchers can make informed decisions about their operations. The project will be a highly collaborative effort engaging with multiple stakeholders. University partners will support experiments in photovoltaic installations exploring crop and soil types common to Southwestern ecosystems at agricultural research centers and postharvest processors. Government agencies and agricultural stakeholders managing land on which renewable energy is being developed are also envisioned as project partners. The project just kicked off in 2023 and will begin by defining knowledge gaps about potential agrivoltaic co-benefits and challenges to determine priorities for subsequent research in the region.

Los Alamos National Laboratory

One of the first agrivoltaics projects I learned about was in the El Rito area led by Los Alamos National Laboratory researcher Sanna Sevanto to support Trollworks, a biochar production equipment manufacturer located in Santa Clara, NM. Funded through the New Mexico Small Business Assistance Program, the researchers tested the effects of biochar on plant growth in an agrivoltaics setting at the solar installation located at Northern New Mexico College’s El Rito campus. Growth and productivity of tomato and Swiss chard was compared on plots where originally non-arable soil was amended to crop growth by incorporating compost and a compost-biochar mixture to the original soil under and next to the solar panels (see photo). The 1.5-megawatt solar installation itself was constructed in 2019 under a partnership between Northern New Mexico College, Kit Carson Electric Cooperative (KCEC), and Guzman Energy. The array helps to transition not only the college, but also the entire KCEC membership and communities west of the Rio Grande served by KCEC toward achieving 100% daytime solar power.

SunShare

Community solar offers a particularly exciting opportunity for agrivoltaics in New Mexico. Signed into law in 2021, the program administrator awarded the first 200 megawatts of capacity to multiple solar developers to construct projects up to 5 megawatts each that will offer subscriptions to customers of the three investor-owned utilities in the state. One of those developers is SunShare, a developer of community solar installations founded in 2011. In addition to providing workforce development opportunities, lease payments to local landowners, and electric bill discounts to low-income subscribers, SunShare will be working with New Mexico Healthy Soil Working Group to incorporate agrivoltaic design concepts into their New Mexico projects. SunShare already has some demonstrated experience with agrisolar on a project in Minnesota working with local farmers on vegetable production and an apiary located within the solar panel rows (see Minnesota Farm Guide: Agrivoltaics—Solar plus farm production is gaining ground).

Sandia National Laboratories

The final agrivoltaics project I’d like to highlight is from a diverse team led by Dr. Ken Armijo at Sandia National Laboratories with partners at SkySun, University of New Mexico, Jemez Mountain Electric Cooperative, Rio Grande Community Farm, and my own company, Circle Two. The project started this fall and will explore a novel solar technology developed by Skysun and Sandia over the next two years including laboratory testing at Sandia, field testing at Rio Grande Community Farm and assessing the commercial potential within the Jemez Mountain Electric Cooperative service area. The unique design of the photovoltaic system (see image) will allow improved crop cultivation access with tractors and personnel along with more efficient operations and maintenance over commercially available fixed-framed agrivoltaics installations. The agrivoltaics system will be connected to a battery storage and control system forming a microgrid to power on-site loads including an electric tractor and irrigation pumps. This project brings my agrivoltaics journey full circle starting with that stack of solar panels in the barn and now exploring the potential benefits of combining solar energy and crops in the field at the nearby fields at Rio Grande Community Farm.

Click here to view the original post and photos on the New Mexico Healthy Soil blog.

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AgriSolar News Roundup: Minnesota Agrisolar Project, Follow the Sun Tour in Oregon, Agrisolar Funding in Massachusetts, Protecting Future Farmland Act in Wisconsin 

USDA Joins Great Plains Institute and Big River Farms in Minnesota Agrisolar Project 

“Officials from the U.S. Department of Agriculture (USDA) joined Great Plains Institute (GPI) and Big River Farms announced GPI and Big River Farms’ ‘Solar Farmland Access for Emerging Farmers’ demonstration projects alongside project partners Connexus Energy and US Solar. As the country and Minnesota both take steps to convert our energy supply to be derived from carbon-free sources, this pilot project is setting out to solve for how solar energy development can be increased while also preserving agricultural land for the people who grow the state and nation’s food.  

Funded by the Mortenson Family Foundation and with additional support from the National Renewable Energy Lab (NREL) and Argonne National Lab, these agrivoltaics projects aim to demonstrate safe and scalable operational practices for electric cooperatives and solar site owners to provide farmland access for emerging farmers inside the fence of solar facilities.” – Globenewswire.com 

AgriSolar Clearinghouse’s Follow the Sun Tour Visits Oregon 

The AgriSolar Clearinghouse’s Follow the Sun Tour visited the North Willamette Research and Extension Center in Aurora, Oregon, on September 18, 2023. The research center hosts an agrivoltaic project, where the University of Oregon studies combining crops and solar energy on the same parcel of land. Event attendees participated in a tour of the agrivoltaic site, guided by lead researcher Dr. Chad Higgins. After the tour, everyone enjoyed a lunch and round-table discussion in the conference room of the facility.  

The research conducted at the facility includes showing that solar arrays could be used as resources for plant productivity and that solar panels on agricultural lands maximizes their efficiency. Attendees discussed details related to these studies during the tour, which also included financial questions and scalability. 

Blue Wave in MA Secures $91 Million for Agrisolar Development 

“Northeast U.S. solar developer and operator BlueWave received $91 million in financing, which the company says will allow it to achieve long-term ownership and management of its portfolio of projects. 

The financing will go toward the construction of five projects featuring dual-use solar development attributes, called agrivoltaics, in Massachusetts. These projects are “strategically implemented to benefit all parties impacted by the projects,” including landowners, farmers and the surrounding community, according to BlueWave. The financing includes a $64 million debt raise with KeyBank, and $27 million tax equity raise with U.S. Bancorp Impact Finance.”– PV Magazine  

Wisconsin Bill Introduces the Protecting Future Farmland Act 

“U.S. Senators Tammy Baldwin (D-WI) and Chuck Grassley (R-IA) introduced the Protecting Future Farmland Act, new legislation to support farmers’ land stewardship efforts as many choose to deploy solar energy on their land. The legislation will ensure that federal investment in rural energy projects prioritizes both land stewardship and responsible deployment of renewable energy to protect America’s farmlands for future cultivation.” Senate.gov 

Dual-Use Solar in the Pacific Northwest Summer 2023

This report updates readers on new research in dual-use solar and explores important considerations for the implementation of dual-use solar in the Pacific Northwest region. In the last few years, new findings suggest there are many environmental and economic benefits of creating multi functional systems that combine and prioritize multiple land uses. New research of dual-use solar facilities shows increased yields in some crops and decreased water needs; benefits to grazing animals such as decreased heat stress; improved ecosystem services such as better water quality, erosion control, carbon storage, and pollination services; and further opportunities for dual-use implementation.

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AgriSolar News Roundup: Wyoming Solar Grazing, French Agrisolar Study, Bipartisan Agrisolar Support 

$500 Million Solar Grazing Site to be Constructed in Wyoming 

“A proposed solar farm near Glenrock will cover 4,738 acres on land bordering the North Platte River, the equivalent of more than 3,500 football fields. When online, it will provide 500 megawatts of solar power and include two battery storage facilities. And there will still be room for the land to support a sheep-grazing operation after construction. 

The $500 million project is scheduled to begin construction in March 2024, and if all goes as planned, will come online in July 2026. The project will be built entirely on private land, and Willox said the developer and landowner have agreed to allow sheep grazing underneath the panels.” – cowboystatedaily 

French Study Shows Benefits of Agrisolar in Water Resource Management 

“France’s Sun’Agri has revealed the results of a test showing how agrivoltaic installations effectively lower temperature and relative humidity during periods of drought. Amidst an ongoing heatwave in southern France, Sun’Agri, a French agrivoltaics specialist, has released its latest findings on the impacts of its technology on water resource management. 

The company conducted an analysis on the effects of solar panels on apple, cherry, and nectarine trees across three sites in La Pugère, Etoile sur Rhône, and Loriol, southern France. The study demonstrated that the PV installations reduced temperature and increased relative humidity for the crops underneath the panels during hot weather, compared to reference areas without protection.” – PV Magazine  

New Bill Shows Bipartisan Support for Agrisolar Development 

“The latest demonstration of bipartisan support for agrivoltaics comes from the offices of US Senators Martin Heinrich of New Mexico and Mike Braun of Indiana. They introduced the new Agrivoltaics Research and Demonstration Act of 2023 in the Senate on May 31. 

This bill will research agrivoltaics — solar panel systems that can be deployed over crops that can benefit from partial shading during the day — and how they can help farmers get more out of their fields.” – Cleantechnica 

Grassland Carbon-Water Cycling is Minimally Impacted by a Photovoltaic Array

In this study, researchers used field measurements and a plant hydraulic model to quantify carbon-water cycling in a semi-arid C3 perennial grassland growing beneath a single-axis tracking solar array in Colorado, USA. Although the agrivoltaic array reduced light availability by 38%, net photosynthesis and aboveground net primary productivity were reduced by only 6–7% while evapotranspiration decreased by 1.3%. The minimal changes in carbon-water cycling occurred largely because plant photosynthetic traits underneath the panels changed to take advantage of the dynamic shading environment. The results indicate that agrivoltaic systems can serve as a scalable way to expand solar energy production while maintaining ecosystem function in managed grasslands, especially in climates where water is more limiting than light.

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Solar Shepherd in Massachusetts: Solar Grazing 

By Allen Puckett, NCAT Technical Writer 

July 2023 

The Solar Shepherd provides grazing services in Brookfield, Massachusetts, with 75 sheep that graze a solar array site owned by SWEB Development, a European clean energy firm. This beneficial partnership was born when SWEB reached out to Solar Shepherd for grazing services after seeing their solar-grazing sites on social media. Learn more about the partnership in the AgriSolar Clearinghouse’s video How a Shepherd and Solar Developer are Joining Forces to Grow Sheep, Clean Energy. 

Solar Shepherd’s founder and owner Dan Finnegan is a third- generation sheep farmer in eastern Massachusetts. His history working in a corporate environment led him to think more about what was important to him—the land, local farming, and clean energy. While he likes raising sheep, there wasn’t enough acreage for it to be profitable without agrisolar sites. 

“It wouldn’t be enough to produce a living for a family,” he said. “This is more than a hobby-farming operation. With solar grazing, we dramatically expand our flock. We work hard to be competitive with landscapers on these sites. The grazing fees mitigate the costs and pay down the investment to take the show on the road (transporting sheep to solar sites). We’re used to farming out the back door, and now we have sites spread hundreds of miles apart. The grazing fees make that cost affordable.”  

“I saw a solar array built on a lambing pasture, and a landscaper showed up with a tractor and started mowing up the solar arrays. He was going about 30 mph with a batwing sprayer and was mowing the rows and hosing down the panels around the arrays. I was thinking, they should just put the sheep down there and let them graze,” Dan recalled. 

Solar Grazing Site Specifications and Management  

The site is in a 15-acre array that produces 5 MW of DC and 3.375 MW of AC, enough to power approximately 1,100 homes. A landowner leases the land to SWEB, and SWEB hires Dan to graze the solar arrays with the sheep. The pricing is relatively the same as traditional mowing and gas-powered landscapers, but grazing sheep comes with many environmental benefits, such as enhanced landscape stabilization that directly benefits the solar companies. This stabilization includes deeper root systems on previously rocky terrain, improved turf health, and significant runoff reduction. 

Solar Shepherd practices rotational grazing on their sites, which allows more carbon in the soil and retains more moisture. “We see that impact very rapidly. There are some sites we had that, in just one year, the customer came to us and said, ‘I can’t believe the impact the sheep had on the vegetation sustainability. It was rocky before, and now there are deeper root systems, stabilized soil.’ Erosion is a big concern at the base of the panels. A direct benefit to the solar companies is stabilizing that ground,” Dan added. 

There’s also the “Fuzz and Buzz” – a solar seed blend used at the Brookfield site that benefits pollinators and sheep. It’s not as robust of a floral bloom, but the bees and sheep benefit greatly from this blend. A gas-powered mower removes all the vegetation on an array in a single day. The sheep take around a month to “mow” the same array. This allows valuable pollinator habitat to be left for the bees and birds. There’s good seed-to-solar contact, and the imprints from the sheep hooves allow the seeds to be captured in the soil. The sheep help the effectiveness of reseeding a site and some graziers will run the sheep back over the seeds to help stomp them down into the earth. 

Solar grazing includes running three main operations: a sheep farm, a trucking company (as you move the animals), and a commercial landscaping business. “It’s more than just opening the gate, throwing the sheep in there, and driving away. There are always some sites that require things outside the lines,” said Dan.  

Dan’s partner, border collie Reggie, has been vitally important in effectively managing the sheep on solar sites. In the trucking operation, sheep are loaded in and out of trucks over and over, and that requires collecting them from one site to another to be loaded into the trucks.  

Reggie is immensely valuable in this process. She rounds up the sheep quickly, whereas it would take multiple human workers significantly more time. She is vital to effective time management (and cost, if you consider paying multiple workers to round up sheep all the time). Reggie moves the sheep around the array in accordance with rotational grazing practices. 

Grant Incentives in Massachusetts 

Massachusetts does have a grant program for dual use of solar (Massachusetts SMART Initiative), but it is “written in such a fashion that it can be difficult to be profitable,” said Dan. The grant does not apply to sites that already exist, and it requires panels to be built 10 feet off the ground. Solar Shepherd has not received this grant and has also not yet grazed an array that fits the 10-foot grant requirement.  

Livestock production is diminishing in Massachusetts and what’s left is small-scale vegetable farming. Dan speculates that the state is writing laws for solar development incentives with this in mind instead of grazing sheep under solar panels. 

Community Response 

“The community loves what we’re up to,” said Dan. “We had about 500 comments (on the recent video featured on CBS) and all of them were loving what we are doing. There are a few political comments. So, grazing sheep on solar might bring some unification from a political perspective.”  

He also added that, “At least half the time I show up, there is a family there outside the gate at the fence watching the sheep. People are wanting to bring kids out to the sites to see the sheep. I’d like to do a program where people can come see them. We would love to host a solar event. We’re going to bring some sheep to town off the hill in Brookfield so people can see them and interact with them. I have a dream of bringing a bus load of kids out here to see how bees, sheep, and everything all come together.” 

Since the Brookfield location is an ancient hay site where indigenous peoples managed the land when colonists first arrived, not damaging the vegetation or compacting the soil during the solar array installation was very important. This priority to minimize damage to the land could have a positive impact on community support for a solar site, particularly on ancient farmland or similarly valued sites. Communities like to see that a (solar) development company cares about the land and the process of development. 

Considerations for New Sheep Graziers 

New sheep graziers or those thinking about getting into sheep grazing on solar sites should consider a couple of things throughout the process. Educating themselves on what’s happening on the solar array is very important. “They don’t have to be engineers,” says Dan, “but they should understand what’s happening and what the potential dangers are and keep themselves and animals away from those areas. Stay out of areas where you might think ‘I should have an electrician in there.’ These are areas that contain things like cable trays and equipment pads.”  

Don’t move forward with grazing a solar site if you haven’t walked the location and examined it for suitable conditions for your sheep. If construction techniques did not leave a space where you would feel comfortable leaving the sheep, such as poor wire management or dangerous or sharp edges on array components, it may be a good decision to decline grazing in that location.  Dan says the sites he turns down are for animal welfare reasons. There might not be enough nutrition on the site, but it is usually wiring management. A good perimeter fence can also make a site more ideal for sheep.  

Operating a grazing operation on your own property requires having a plan for food and water delivery, as well as for avoiding predation. A plan should be in place for responding to issues that may arise on the site and with little notice. Solar Shepherd has a 24-7 hotline for such issues. 

For fencing, Dan prefers to use electric netting, which provides effective  protection from predators. Coyotes prefer to go under the fence rather than over it, and considering such nuances in predator-prevention strategies can help design a fencing system that is most effective for your area and your circumstances. Hiring people who think from the sheep’s perspective is important, says Dan. Fortunately, he has not had any issues with predation to his sheep.  

The Future of Solar Shepherd and Solar Grazing 

The future of Solar Shepherd is looking bright. It originally took the company approximately one year to get hooves on the ground at a solar site. Now it only takes about a week or two. “I feel great about the solar grazing future and Solar Shepherd. The sales pitches are getting shorter and shorter. The world is becoming aware of this subject. Five years ago, it was, ‘You’re doing what?!’ The last pitch I gave was an hour-long presentation. I got 15 minutes into the meeting, and people said, ‘It’s great; we are ready to sign.’” 

Enabling Real-Time Monitoring of Environmental Conditions and Soil Health Through the Use of Standalone Photovoltaics and Off-the-Shelf Systems

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.

Environmental Co-Benefits of Maintaining Native Vegetation With Solar Photovoltaic Infrastructure

In this study, researchers monitored the microclimate, soil moisture, panel temperature, electricity generation and soil properties at a utility-scale solar facility in a continental climate with different site management practices. The vegetated solar areas had significantly higher soil moisture, carbon, and other nutrients compared to bare solar areas. However, the benefits of vegetation cooling effects on electricity generation are rather site-specific and depend on the background climate and soil properties.

Earth-s-Future-2023-Choi-Environmental-Co‐Benefits-of-Maintaining-Native-Vegetation-With-Solar-PhotovoltaicDownload

VIDEO: How A Shepherd and Solar Developer Are Joining Forces to Grow Sheep, Clean Energy

The National Center for Appropriate Technology’s (NCAT) AgriSolar Clearinghouse today premiered its short film “The Solar Shepherd” during the 2023 Solar Farm Summit in Chicago.

The film showcases a family-owned farm in central Massachusetts that’s raising sheep and solar energy on the same piece of land. AgriSolar or agrivoltaic partnerships are growing across solar-appropriate farmland in the U.S., providing a new revenue source for farmers, clean energy for surrounding communities, and myriad benefits to crops, livestock, and pollinators.

“It’s been a wonderful friendship between the two businesses,” says Solar Shepherd LLC founder Dan Finnegan. “We can’t access enough land to keep our farm sustainable, without this partnership with solar, we wouldn’t have a successful farm, we simply don’t have enough acres to graze.”

Finnegan partnered with SWEB Development Inc. on the 15-acre solar array which provides enough clean energy to power 1,100 homes and has so-far raised 45 lambs to maturity.

“You can have this partnership in a one-acre field, a 15-acre field up to a couple hundred acres,” says Joe Mendelsohn, project developer with SWEB Development Inc.

NCAT’s AgriSolar Clearinghouse is connecting businesses, land managers, and researchers with trusted resources to support the growth of co-located solar and sustainable agriculture.

“Tremendous potential exists in partnerships between farmers and solar developers,” says NCAT Energy Director Stacie Peterson, PhD. “As the demand for solar energy grows, it’s up to us to be good stewards of the finite land resources we have and maximize the benefit to farmers, communities, and the environment.”