Tag Archive for: AgriSolar

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.

AgriSolar News Roundup: Bipartisan Agrivoltaics Bill, Danish Solar Grazing, Ohio Agrisolar Project 

U.S. Senators Introduce Bipartisan Bill that Supports Agrivoltaics Research 

“U.S. senators on both sides of the aisle have recently proposed two bills to boost agrivoltaics, the double-duty climate solution that pairs solar panels (photovoltaics) with agriculture — or closely related land uses that benefit farmers and ecosystems. 

In May, senators Jeff Merkley (D-Oregon) and Cory Booker (D-New Jersey) introduced the Pollinator Power Act. Its passage would direct the U.S. Secretary of Agriculture to prioritize solar projects funded by the Rural Energy for America Program that create habitat for pollinators underneath the panels. Pollinators such as bees, butterflies and beetles are responsible for pollinating three-quarters of flowering plants and 35 percent of food crops, but populations are in striking decline, in major part because of habitat loss. 

On the heels of the pollinator bill, senators Martin Heinrich (D-New Mexico) and Mike Braun (R-Indiana) worked across the aisle to jointly propose legislation that could catalyze the growth of agrivoltaics in the U.S.: the Agrivoltaics Research and Demonstration Act. If made law, the act would invest $15 million per year from 2024 to 2028 — $75 million total — toward agrivoltaics research and demonstration projects.” – Canary Media 

“”Agrivoltaic systems within the legislation apply to lands where agricultural activities and solar energy production are simultaneously taking place. The USDA’s National Institutes of Food and Agriculture would work closely with the Department of Energy to establish a network of demonstration sites nationwide through the legislation. Agrivoltaic advocates note that the practice can increase farm profits through the reduction in energy use or selling of energy generated on-farm. Other supporters of the legislation include American Farmland Trust (AFT) and the National Sustainable Agriculture Coalition.” – AgNet West 

Danish Agrisolar Project will Utilize Sheep Grazing 

“Danish renewable energy company Eurowind Energy is developing an agrivoltaic project in Romania, a 70 MW photovoltaic park that will combine solar energy with agriculture. The solar park will span 80 hectares, with 119,184 modules, while its projected annual electricity output is about 102 GWh, enough to supply some 30,000 households. 

At the same time, 130 farmers will be able to use the 80-hectare land for their animals to graze, according to media reports, which cited a press release from Eurowind Energy. 

Recently, works were launched on Croatia’s first agrisolar power plant, in a project that will involve sheep farming. Earlier this year, Hungary-based BSD Invest Europe said it was planning to install a solar park with on the Serbian-Montenegrin border, which would simultaneously be used for sheep farming and growing berries.” – Balkan Green Energy News 

Ohio Agrisolar Project Funded by State Agency 

“The Madison Fields project is being developed by Savion Energy of Kansas City, Missouri, and is expected to be completed in December 2023 and plans to operate for at least 30 years. The company is working with Ohio State University’s Extension Service on pairing agriculture with solar. 

The 180-MW solar facility is expected to generate the equivalent power for up to approximately 35,000 households. The project creates two full-time permanent jobs and 596 full-time temporary positions during the construction phase.  

The company has received community support for the project including from the Board of Commissioners of Madison County, the Madison County Soil and Water Conservation District, Pike Township and Fairbanks Local School District.” – Solar Power World 

Case Study: Cozy Cove Farm

By Anna Adair, NCAT Energy Program Assistant

Just outside of Gurley, Alabama, a herd of grazing llamas and alpacas find refuge from the sun underneath a solar array. Tony and Cozette O’Neil, owners of Cozy Cove Farm, have been raising the animals since 1995, shearing their fleece to make yarn and felt. Today, the O’Neils are also proud renewable energy producers for their community, thanks to the 50-kW solar system that has been generating electricity since February 2013.

A retired NASA engineer, Tony has believed in the power of solar technology since his work on the solar-powered space station Skylab in the 1970s. In 2012, with an electric bill sometimes reaching $500 a month, he learned that he could generate and sell renewable energy to the Tennessee Valley Authority (TVA). The cost of solar equipment was decreasing around this time as well, making it the ideal time to install solar on their 54-acre farm. Working with Outpost Solar, the O’Neils planned a photovoltaic system consisting of 208 fixed-tilt panels in a 100-by-100-foot area, tucked away on a corner of their pastureland next to the Flint River. Because the array was built on a floodplain, the panels had to be elevated to seven feet above ground level. The unexpected change to the design had an upside: shade for more than 100 llamas and alpacas that call Cozy Cove Farm home.

The O’Neils took advantage of several incentives to build their solar array, which totaled $160,000 upon completion. The majority of the cost was covered by a 30% federal tax credit and a 25% USDA REAP grant. Smaller grants from state and local programs brought the out-of-pocket cost to just under $48,000. Alabama Farm Credit provided the O’Neils with a loan for the remaining amount, which they were able to pay back completely in October of 2017. In just under five years, the array paid for itself thanks to a 10-year contract with the TVA that paid them 22 cents per kWh of electricity generated.

Today, 10 years after the solar system’s completion, the O’Neils continue to benefit from its installation. Service and repair costs have been low, with only one panel needing replacement from damage in the first year. At the end of their initial contract, the O’Neils signed a subsequent contract for an additional 10 years that allows the TVA to purchase the electricity they produce at the same rate their utility charges them for their energy consumption. “This provides us with approximately $3,500 a year after all of our farm energy needs are paid for,” says Tony. He also encourages other farmers considering installing solar on their property to think long-term. “Electricity cost is only going to increase in the future, and the cost of solar panels and inverters are at an all-time low at present.” While many agrisolar projects are still in the first few years of operation, Cozy Cove Farm stands as a shining example for how agrivoltaic installations can benefit their owners for over a decade.

Photo credit: Scott Sklar, George Washington University

Increasing the agricultural sustainability of closed agrivoltaic systems with the integration of vertical farming: A case study on baby-leaf lettuce

In this case study, researchers quantified the increase of land productivity derived from the integration of an experimental vertical farm (VF) for baby leaf lettuce inside a commercial photovoltaic greenhouse. The mixed system increased the lettuce yield by 13 times compared to a non-VF PV greenhouse and the average LER was 1.31. However, only 12 %
of the energy consumption was covered by the photovoltaic energy system.

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Modeling Potato Crop Yields for Different Agrophotovoltaic Shading Scenarios

The objective of this thesis work is to evaluate the introduction of agrivoltaics in Italy through the study of the effect of the presence of photovoltaic panels on the final yield of potatoes in Ferrara, Italy. The findings of this preliminary study indicate that agrivoltaic systems should be designed while taking into account the need to ensure a minimum level of incident radiation at least in the first two months of cultivation, to avoid an inter-row production drop. Furthermore, photovoltaic panels are not responsible for the absolute low yield in years with unfavorable weather conditions, such as cold years; on the contrary, they may mitigate the damages to the crop by creating an underneath microclimate and the resulting higher temperature, which however is a hypothesis to be verified in more detail in future studies.

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Case Study: Mustang Two Solar Facility

Indart sheep between rows of solar panels.

By Anna Adair, NCAT Energy Program Assistant

Just outside of Stratford, California, hundreds of sheep spend their days grazing between rows of solar panels at the Mustang Two solar park. The site, owned by Idemitsu Renewables, sits on 1,160 acres and produces enough clean energy to power over 50,000 homes. The 150-megawatt facility was constructed in 2020, with the sheep taking up residence shortly after. Courtesy of Indart Solar Sheep Grazing, the herd helps maintain the vegetation growing around the solar panels while also working to improve the biodiversity of the plants on site.

Indart Solar Sheep Grazing owner Ryan Indart had grazed several sites prior to adding Mustang Two to the list, building positive relationships within the solar community along the way. When a friend at SOLV Energy, the operators of the site, informed him that the conditional use permit required grazing, Ryan jumped at the opportunity. Mustang Two was the first site Ryan had to compete for, but he successfully won the bid to be the grazier on site. In 2021, he unloaded his sheep onto what was, at the time, the largest site in his portfolio.

Two years later, the Indart sheep continue to do their part in maintaining a safe, well-managed solar site. Despite not being the easiest location to graze, Ryan and his sheep have received great feedback from both SOLV and Idemitsu. The facility has a dense foxtail barley population, and the sheep can be selective about when they choose to eat the plant. Although the foxtail may not be ideal, grazing has many environmental benefits when done under the watchful eye of a knowledgeable rancher. Over time, Ryan’s sheep will help diversify the plant life and improve the soil quality at Mustang Two, as well.

Photo by NCAT

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

Solar Energy Development on Farmland: Three Prevalent Perspectives of Conflict, Synergy and Compromise in the United States

This article uses the food–energy–water (FEW) nexus framework to delineate three different perspectives of solar energy development on farmland. The first two perspectives fit into the FEW nexus language of “trade-offs” and “synergies” respectively, arguing that solar energy development either conflicts with agricultural land use and food security or, alternatively, that the two land uses can be co-located appropriately to create agrivoltaic systems. The third perspective is a compromise, arguing that solar energy preserves farmland for future agricultural use.

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AgriSolar Podcast Ep. 6: The Big Picture and Nitty Gritty of Agrisolar

This episode is a conversation between NCAT Energy Program Director Stacie Peterson and Iain Ward, a farmer and founder of Solar Agricultural Services.

It is the sixth in a series of AgriSolar Clearinghouse podcasts that are being featured on ATTRA’S Voices from the Field podcast.

Stacie and Iain discuss the potential of agrisolar as way to remove barriers to entry into farming, how agrisolar is shifting the solar industry to consider regenerative agriculture, practical considerations for getting started in agrisolar, Iain’s connection with Wendell Berry, and Wendell’s thoughts on co-locating solar and agriculture. 

Related NCAT Resources:

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Contact Stacie Peterson at stacieb@ncat.org.

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You can get in touch with NCAT/ATTRA specialists and find access to our trusted, practical sustainable-agriculture publications, webinars, videos, and other resources at ATTRA.NCAT.ORG.

This material is based upon work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Solar Energy Technologies Office Award Number DE-EE000937. Legal Disclaimer: The views expressed herein do not necessarily represent the views of the U.S. Department of Energy or the United States Government.

Case Study: Slate Solar PV Park

Indart sheep grazing around solar panels.

By Anna Adair, NCAT Energy Program Assistant

Located in Kings County, the Slate Solar PV Park produces power for hundreds of thousands of California citizens, while simultaneously providing food and shade for its resident sheep herd. The 390-megawatt site, owned by MN8 Solar and operated by Canadian Solar, rests on 2,120 acres and consists of almost 951,000 bifacial solar panels. Rather than relying solely on mowing, the operators count on Ryan Indart and his company Indart Solar Sheep Grazing to provide anywhere from 1,150 to 2,000 sheep to keep most of the site’s vegetation under control.

Ryan credits his solid relationships with his clients for the opportunity to graze at the site. The Slate facility is adjacent to another PV park, known as Mustang 2, where Ryan’s sheep were already grazing during Slate’s construction phase. He reached out to his contacts at Mustang 2 to see if anyone had connections at Canadian Solar and was given the number of the asset manager for Slate. One phone call and a positive reputation amongst the solar operators in his area later, Ryan signed a three-year contract to graze his sheep as part of Slate’s vegetation management plan.

Today, Ryan says he believes both Canadian Solar and MN8 Solar are happy with the partnership. Grazing animals can help lower the operations and management costs at a solar site, which is a high priority for the businesses involved. Although Slate does mow some sections of the facility as needed, the Indart sheep significantly reduce the area that needs mowing, all while finding respite from the hot California sun underneath the panels.

Photo by NCAT