Final report for FW23-413
Project Information
The research being conducted at JSG addressed two questions: how to build more profit margin and climate resilience for production farmers through agrivoltaic systems, and how to sustain secure food production in semi-arid ecosystems as climate change affects land management methods and water access.
The ongoing potential for this project to contribute to sustainability and resilience initiatives through informing the design of an agrivoltaics system was and is significant. The profession of agriculture and the food system at large increasingly rely on diversifying approaches to build resilience into our systems, such as those investigated in this study.
While still early in the multi-year research, we continue to expect novel results from the project, which will expand and improve our basic understandings of ecosystem function, how novel ecosystems provide ecosystem services, and how we can use ecosystem ecology to improve environmental impacts of human activity. At its core, successful adaptation of agrivoltaic methods on a large scale will provide multiple streams of income for farmers, and reduce water usage in food production.
We disseminated our preliminary findings through partnerships with farmers across the region and country, leveraging the network of coalitions and organizations with whom we partner and of whom we are members and leaders, including: National Center for Appropriate Technology (NCAT)’s AgriSolar Clearinghouse, National Young Farmers Coalition, National Farmers Union, Rocky Mountain Farmers Union, Colorado Department of Agriculture, Mile High Farmers, Flatirons Farmers Coalition, and more.
1) Demonstrate and quantify the potential agricultural production benefits resulting from an innovative, integrative agrivoltaic system design;
2) Characterize the most effective growing configurations across multiple variables, including: crop types and varieties, solar panel heights, irrigation amounts, and gradients of shade underneath solar panels;
3) Determine productivity (measured in plant growth and harvest yield) of specific crop and variety types across variations throughout the season, as compared to the full-sun control plot; and
4) Conduct outreach to local farmers and other potential agrivoltaic adopters on optimal configurations, economic tradeoffs, and agricultural activities that could realize revenue alongside enhanced crop production and significant water savings.
|
Date |
Activities |
Team members |
|
April 2023 |
Researchers begin measuring baseline data for the season; finalize preparation for 2023 season; establish regular communication including biweekly meetings for the duration of the season |
Meg, Liza, Greg & research support team |
|
May-June 2023 |
Establish research plots, plant crops (seeds and seedlings), begin farm cultivation |
Meg, Liza, & farm team |
|
Late June - October 2023 |
Monitor production growth and conduct harvests |
Liza, Greg & research team |
|
Late October - November 2023 |
Research teams record end-of-season measurements; winterize plots (remove crop residue, seed cover crops and/or mulch); season debrief and planning meetings |
Meg, Liza, Greg |
|
November - December 2023 |
Crop plan for 2024, seed purchase |
Meg, Liza |
|
December 2023 - March 2024 |
Distribute 2024 season findings amongst research partners & farmers; prepare for beginning farmer incubator plots & training |
Meg, Liza, Greg |
|
February 2024 |
Begin growing seedlings in greenhouse for 2024 season |
Liza |
|
April 2024 |
Repeat annual process of researchers measuring baseline data for the season |
Meg, Liza, Greg |
Cooperators
- - Technical Advisor
- - Producer
- - Producer
Research
This project supported a collaborative research farm at the innovative agrivoltaic (agriculture + photovoltaics) solar installation in Longmont, Colorado: Jack’s Solar Garden (JSG), the largest agrivoltaics site in the United States dedicated to specialty crop research. At JSG, Sprout City Farms (SCF) has organically grown diversified vegetables under three acres of raised solar panels (reaching 6 and 8 feet tall) since 2021.
Throughout the course of this grant period, SCF managed the research farm plot at JSG on behalf of research partners at the University of Arizona (UofA), building on the ongoing research at their site in Tuscon; SCF is the farmer and agricultural advisor for crop research efforts. SCF assisted UofA researchers in collecting the quantifying data of our crop production, including plant growth (measured in photosynthesis rates, phenology of bloom times, and biomass produced), and harvest yield.
We grew a minimum of two varieties of each crop being studied (i.e. Golden beets and Red Ace beets) to account for potential variations in performance between varieties. Criteria used for crop selection included standard regional crops (potatoes, dry beans), importance to market growers (tomatoes, peppers), and representation of a diverse array of crop families and categories (root vegetables, leafy vegetables, fruiting crops, etc). Each crop set was planted in multiple production beds between rows of solar panels that each receive a different amount of sun and shade throughout the day (varying from 50-75% shade), and the sets are replicated under the six foot panels, the eight foot panels, and the control plot (located outside the solar panel field in full sun, to represent normal field conditions). The crop plantings are duplicated again for the irrigation reduction experiment, wherein crops are watered for half as much time as their counterparts in order to determine whether the microclimate of an agrivoltaic system supports reduced irrigation needs. Each crop set is labeled with crop name, variety name, and percent of irrigation (100% or 50%). Measurements are taken regularly as we maintain the farm and harvest food throughout the growing season, to study differences in growth and yield across all of the variables we are tracking.
This project has been and continues to be the largest and most comprehensive study of irrigation benefits and tradeoffs at an agrivoltaics site in the United States. Moreover, this study remains the first agrivoltaics project to consider multiple panel heights and their impacts on irrigation requirements, the first study to consider multiple vegetation types on the same site, and the first study to compare across shading gradients. This work is setting a foundation for agrivoltaic designs to provide multiple benefits across agricultural and solar sectors in Colorado and beyond. This project has the potential to facilitate optimized irrigation systems in Colorado and elsewhere for agrivoltaic systems.
Our research partners are still quantifying microclimate impacts, benefits, and tradeoffs of different agrivoltaic configurations to understand the parameters governing microclimate modifications and the extent to which the microclimates can be modified to benefit both the solar and agricultural subsystems. Specific metrics of interest included soil moisture, air temperature, solar panel temperature, relative humidity, and light intensity. They utilized meteorological instrumentation stations and typical solar installations in each research plot to measure incoming and outgoing short- and long-wave radiation in order to describe how incoming energy is absorbed, stored, reflected, or re-radiated in the form of latent or sensible heat. This allowed us to facilitate consistent irrigation trials and insights across the different vegetation types.
This award has supported the farmers and research coordinators at Jack’s Solar Garden in operating a research vegetable farm site. The research incorporated in this Western SARE award is part of a long-term research project, so our preliminary findings are not final results.
Some early qualitative patterns that we noticed throughout the award period include promising results so far:
- Leafy greens and root vegetables, traditionally early/late season produce, thrive particularly well under solar panels in ways that they do not sustainably grow in non-agrivoltaic designs. This includes unique crop results including elbow-high kale, arugula that never bolts, non-bitter lettuce in the heat of July, and turnips/beets/radishes that grow to their full potential in peak summer - otherwise unheard of in semi-arid Colorado.
- The incorporation of shade and a cooling microclimate does not deter the production of full-sun crops, and instead minimizes the amount of water they (and partial-sun crops) need to produce at highest capacity.
- Solar panels provide a level of protection from adverse weather, including rainstorms and hail, which would otherwise cause significant crop damage.
- The most negatively-impactful variable to crop production so far is pests, namely grasshoppers and rabbits, eating the vegetables as they grow. As organic producers, Sprout City Farms recognizes this risk and is consistently implementing new methods to deter these pests without incorporating chemicals that are harmful to humans.
The unique longevity and mid-season production quality of heat-intolerant crops such as greens and root vegetables usually limited to early/late season, can be reasonably attributed to the cooling microclimate and higher rates of shade (sun exposure on the beds varies between 50% - 70% depending on proximity to the panels) beneath the solar panels.
Research Outcomes
Overall, Sprout City Farms has sought to determine the best practices of agrivoltaic farming for diversified organic vegetable farmers to replicate operations and incorporate agrivoltaics into their production methods. These early findings indicate that agrivoltaic models can be very successful for crop production, though our design limits industrial-scale production and is highly dependent on human labor. This is one of the factors that we will continue to navigate as we try to establish replicable practices for farmers across the country, while our partners at UofA are gathering quantifiable data to present at the end of the research project period.
We had hoped to have more solidified results by the end of the 2024 season, but due to all the variables already present in farming, we need to conduct more seasons of research before confidently identifying trends and sharing outcomes for farmers, researchers, solar developers, and community members alike who are interested in co-locating vegetable production with photovoltaics. That being said, we have been able to disseminate our early findings to these stakeholders through site visits, conference attendance, and expanding collaborative partnerships.
In the remaining years of the project, we look forward to seeing the comparative results of the quantitative data compiled by the University of Arizona researchers and research coordinators. While Sprout City Farms provides the qualitative farmer perspective, they are the ones tracking microclimate impacts, benefits, and tradeoffs of different agrivoltaic configurations to understand the parameters governing microclimate modifications and the extent to which the microclimates can be modified to benefit both the solar and agricultural subsystems. In the coming years as we continue our collaborations, we will strengthen our findings to share both qualitative and quantitative results of production-scale vegetable growth under a 6-foot and 8-foot agrivoltaic array.
Education and Outreach
Participation Summary:
Throughout the grant period, SCF hosted 15 visits and tours with local growers and farmer advocacy groups, engaging over 1625 people at the farm at Jack’s Solar Garden - 4133 total if you include food recipients. Notable visits have included hosting a bill signing with the Governor of Colorado, Colorado State Senators and the Colorado Commissioner of Agriculture; field days with Department of Energy Principal Deputy Assistant Secretary, Office of Energy Efficiency and Renewable Energy and team; tours with the Department of Energy Technical Monitor and team; and visits from the AgriSolar Clearinghouse of National Center for Appropriate Technology (NCAT). 1,500 of the total individuals engaged can be attributed to our educational site partners, Colorado Agrivoltaic Learning Center, as they regularly host public tours and workshops that include our farmers but are not led by Sprout City Farms itself. Their showcase events included a tour of the research plots, partner presentations on study design and preliminary outcomes, and an interactive question-and-answer session about agrivoltaic models. SCF intends to host more farming partners on site in 2025.
In the future when more comparative quantitative data is finalized, the research team members will host public tours and showcase of their research test plots; deliver a publicly-available webinar highlighting research and preliminary outcomes; and upload their project information and data to the InSPIRE project data portal, which has the nation’s most comprehensive set of agrivoltaics information available.
Sprout City Farms (SCF) remains an active member of Rocky Mountain Farmers Union, National Young Farmers Coalition, CO Fruit and Vegetable Growers Association, Mile High Farmers, and Flatirons Farmers Coalition. We have drawn upon these relationships and networks to foster the growing interest in agrivoltaics and garner excitement for our audiences, and with whom we have shared our initial farming experiences and intend to continue sharing our research findings as they unfold. Our current findings are tied to research outcomes, in which we are seeing production benefits such as longer seasonal growth for root vegetables, protection from adverse weather, and reduced water usage successes through the colocation of vegetable production and solar array.
Furthermore, we have begun preliminary partnerships with solar developers (namely Pivot Solar) in which we intend to be a consultant for their upcoming agrivoltaic designs, in the hopes that their solar configurations account more intentionally for the agriculture side of agrivoltaics. This will be a starting point for more national solar outreach.
Our goal of creating factsheets about agrivoltaics for online and in-person learning was taken on by our partners at Colorado Agrivoltaic Learning Center and can be found on their website (https://www.coagrivoltaic.org/agrivoltaics-101) and attached below.
CALC Consulting Services Description
Financial Considerations factsheet
Education and Outreach Outcomes
Throughout the award period, SCF has deepened our partnership with site partner, Colorado Agrivoltaic Learning Center (CALC), as they have grown their operations throughout 2023 in supporting public education and policy advocacy surrounding agrivoltaics. We share our connections at AgriSolar Clearinghouse of National Center for Appropriate Technology (NCAT), Colorado Department of Agriculture, Rocky Mountain Farmers Union, National Young Farmers Coalition, Flatirons Farmers Coalition, and Mile High Farmers, to host tours and learning opportunities that showcase Jack’s Solar Garden for the aforementioned groups. CALC has come to take the lead on organizing showcase events including public tours of the research plots, partner presentations on study design, and workshops with interactive question-and-answer sessions. While our farmers refine research and agricultural operations each year, we are finding the capacity to lean into collaboration to be a rewarding path forward.
Agrivoltaic vegetable production (incorporation of solar panels with vegetable production and the associated modifications in agricultural methods)