Testing Agrivoltaics in the Ag Reserve
January 5, 2023
“Agrivoltaics,” is a new buzzword in solar energy circles. The term applies to land used for agriculture (“agri”) and for generating solar energy (“voltaics”) by solar panels. Agrivoltaics can refer to just a few solar panels mounted on ground-based structures (as opposed to rooftops) or a whole field of them, with crops or animals grazing underneath.
A successful agrivoltaic project has some type of farming thriving adjacent to or under the panels, with the panels generating sufficient power to justify the economics of constructing and installing them. That can be a tall order—but not an impossible one. Agrivoltaics projects are very much in the research phase. The approach is not a fully proven yet, though it’s being viewed as workable under the right circumstances. For now, much of what’s known about agrivoltaics has come from research in dry areas in the western U.S. Some of these areas are sunnier and hotter than the Mid-Atlantic region in the summer and colder in the winter. Thus, agrivoltaic projects that are successful out west aren’t necessarily relevant to the Mid-Atlantic.
Other concerns and potential downsides are emerging. Ground solar panels can disturb and compact soil. They also decrease the amount of sun that reaches plants, affecting photosynthesis. And ground panels can adversely affect how much rain reaches plants and in what pattern. For example, run-off from panels can cause water to pool in some areas. Another practical concern is how farmers get equipment in and around ground panels. All these issues, and others, are being studied.
Agrivoltaic proposals for the Ag Reserve
In 2020, Montgomery County adopted a zoning change that allowed solar arrays on land zoned for agriculture in Montgomery’s County’s Ag Reserve. The measure was a compromise. It recognized the need to generate more renewable energy in the county while at the same time preserving farming, especially on the county’s best soils. The measure also encouraged more production of rooftop solar. It increased the allowable amount of solar production for landowners from 120% of their personal use to 200%. That meant people could sell any excess solar electricity they generated back into the electricity grid. Community solar arrays, which are smaller than “utility scale” arrays, are also allowed under the measure. They can produce up to 2 megawatts of electricity, and generally require 10 to 12 acres of land. Importantly, placing solar arrays on farming soils designated class 1 or class 2 (high quality soils) is prohibited.
The zoning change also required that community solar arrays must either be pollinator friendly and/or managed for grazing animals and/or used for “agrivoltaic plant material.” That creates complexities, often not fully taken into account by solar advocates. For example: as essential as pollinator plants are to ecosystems, they are not actually considered agriculture. Another example: sheep and goat farming involve far more than simply setting sheep out to graze under solar arrays.
Although there’s no established way to track how much rooftop solar might have increased with the provision for 200% of personal need, we know that several community solar projects have either received or will soon receive conditional use approvals from the Hearing Examiner in the County’s Office of Zoning and Administrative Hearings. But there’s a problem. The Reserve is served by three separate utilities, each with its own policies and practices for approving interconnections to the electric grid from solar arrays. Most of the Reserve is in Potomac Edison territory. That utility has not approved any solar array connections in the Reserve and is unlikely to do so anytime soon. This presents an obstacle to agrivoltaic projects.
Critics of the zoning change that permits solar arrays on farms in the Ag Reserve often allege that not allowing solar arrays on good quality arable land is the main reason farmers and landowners are not pursuing solar projects. In fact, the chief obstacle is Potomac Edison’s current policy with regard to purchasing solar energy from smaller scale arrays and community solar projects.
In late 2022, County Executive Marc Elrich suggested that county-owned property in the Ag Reserve could be considered for a solar array and agrivoltaic experiment encompassing some 400 acres. This is half of a property in Dickerson that the county is required by state regulation to hold for a potential landfill. The property in question is currently farmed and SCA believes that farming should continue on a large portion of this land. We are open to an initial modestly-scaled agrivoltaic experiment at this site. If successful, it could be expanded. Such an experiment could clarify how the generation of solar energy and farming can co-exist in the Ag Reserve. We strongly oppose any future use of this property as a landfill.
The chief advantage of this site for such an experiment is its close proximity to high-energy transmission lines and other energy infrastructure that could provide ease of connection to the grid. The County Executive has pledged to create a stakeholder committee—comprising residents, solar experts, local farmers, and county staff—to advise on the launch of an agrivoltaics experiment at the site. We support such a group.
Among questions and issues the experiment could help address are how solar panels impact (a) rain runoff; (b) air flow; (c) photosynthesis of different vegetables and grains; (d) livestock forage and management; and (e) whether nutrient density and growth rates of produce and livestock are affected. The project should also test soils before panels are installed, and then regularly, once panels are in place. Soil tests should encompass not only traditional measures like pH and NPK (nitrogen, phosphorus, potassium) but also evaluate other soil metrics (such as moisture, soil protein, soluble salts, and active carbon. Notably, solar panels are comprised of minerals and metals (copper, aluminum, nickel, zinc, silicon, gallium, boron, indium, selenium, cadmium, and tellurium), and while research indicates little likelihood of these leaching from panels into the underlying soil, it would be important to periodically test soils on the site both prior to panel installation and periodically during the life of the panels.
SCA welcomes more discussion and careful consideration of agrivoltaics in the Ag Reserve and elsewhere in Montgomery County.
SCA Board Member Ellen Gordon wrote this article.