Tag Archive for: AgriSolar

This paper presents a novel 3D agrovoltaic modelling tool developed in python which enables technical and economical evaluation of potential agrovoltaic designs. It has been designed and applied for fruit crops which typically have a crucial flowering period. To illustrate the potential of this tool, a case study for pear trees in Bierbeek, Belgium is shown. While many geometrical parameters of agrovoltaic systems are fixed in practice, however, there is also the need to model the impact of PV modules on the tree light interception. The results of the modelling show that the amount of solar radiation depends on the modules used, with semi-transparent modules offering better light distribution and reduced crop loss. Based on the modelling, a prototype agrovoltaic set-up with pear trees and semitransparent modules has been built in Bierbeek, Belgium.

A slide presentation by Ku Leuven focusing on suitable sites for agrivoltaics in a pear orchard.

Agrivoltaic systems (AVS) offer a symbiotic strategy for co-location sustainable renewable energy and agricultural production. This is particularly important in densely populated developing and developed countries, where renewable energy development is becoming more important; however, profitable farmland must be preserved. As emphasized in the Food-Energy-Water (FEW) nexus, AVS advancements should not only focus on energy management, but also agronomic management (crop and water management). The researchers critically review the important factors that influence the decision of energy management (solar PV architecture) and agronomic management in AV systems. The outcomes show that solar PV architecture and agronomic management advancements are reliant on (1) solar radiation qualities in term of light intensity and photosynthetically activate radiation (PAR), (2) AVS categories such as energy-centric, agricultural-centric, and agricultural-energy-centric, and (3) shareholder perspective (especially farmers). Next, several adjustments for crop selection and management are needed due to light limitation, microclimate condition beneath the solar structure, and solar structure constraints. More importantly, a systematic irrigation system is required to prevent damage to the solar panel structure. The advancements of AVS technologies should not only focus on energy management, but also food (agriculture) and water management, as these three factors are nexus domains. Since the management of agriculture (crop) and water are parts of agronomic management, future enhancements should emphasize the importance of balancing the two. The agronomic management in AV systems that requires improvement includes crop selection recommendations, improved crop management guidelines, and a systematic irrigation system that minimizes environmental impacts caused by excess water and subsequent agrichemical leaching that could affect the solar PV structure. In conclusion, the advancements of AVS technology are expected to reduce reliance on nonrenewable fuel sources and mitigate the effects of global warming, as well as addressing the food-energy-water nexus’s demands.

Developing methods for the sustainable coproduction of food, energy and water resources has recently been recognized as a potentially attractive solution to meeting the needs of a growing population. However, many studies have used models, but have not performed an actual experiment to directly validate all their predictions. Here, we report a recently-constructed test site on the ACRE farm in West Lafayette, Indiana, consisting of single-axis trackers in a novel configuration atop a maize test plot. We present a methodology to measure irradiance therein with 10-minute temporal resolution, which allows us to validate prior PV aglectric farm irradiance models. In spring 2019, an experimental aglectric system was constructed at the Purdue University Agronomy Center for Research and Education (ACRE) farm. This experiment, commonly referred to as the ACRE Solar Array, comprises of 4 single-axis solar trackers implemented in east-west tracking mode. The solar trackers are raised 20 ft above ground level and welded to steel I-beams for compatibility with current high-yield agricultural practices such as mechanized farming. This work modifies and leverages a previously developed ray-tracing model that calculates irradiance reaching the ground. Using the open-source library PVLib, spatial maps of intensity variation are calculated for direct and diffuse light. Solar input was based on astronomical data calculated in PVLib and historical weather data from West Lafayette. The percentage reduction in irradiance for a simulated structure in comparison with an open field is calculated and referred to as shadow depth (SD). The model is capable of simplistic systems as well as custom array layouts such as the ACRE Solar Array. A methodology for validation of spatial and temporal irradiance maps of non-uniform shadow distributions has been evaluated and shows significant agreement.

A new project funded by Cornell University and the U.S. Department of Agriculture (USDA) will explore the economic benefits of grazing sheep under industrial-scale solar arrays in New York, according to a report by The River. The three-year, $500,000 project will focus on the economic opportunities for a farmer-owned business cooperative that grazes sheep under industrial-scale solar panels. The idea for the project came to life in 2019, when Caleb Scott, a New York farmer, and Todd Schmidt, a professor at Cornell University, discussed the benefits and possibilities of organizing a co-op between solar developers and sheep farmers.

The group of farm and energy advocates developing this project are working to prove the power of agrivoltaics by getting more sheep grazing under solar panels in the Northwest. Agrivoltaics is a growing field combining farm production and renewable energy, benefitting both of these industries, as well as local ecosystems and communities.

“There’s very aggressive renewable energy goals by the state, of which they’re trying to do a lot with solar. This is a real opportunity for growth in a relatively small agricultural production sector in the state,” said Schmidt.

According to the report, New York’s 2019 climate law, the Climate Leadership and Community Protection Act, set an ambitious energy goal of a zero-emissions electrical grid by the year 2040.

For more information on the project, click here.

During this project the team looked for possibilities to implement a movable solar panel system in combination with growing a low revenue crop. The report provides advice on design of movable systems, on the feasibility of the idea, and its influence from and on the society. The report includes the main bottlenecks associated with implementation of the idea. To explore the potential of such a movable solar panel system within a common Dutch arable farm, the team first looked at available literature from previous research and existing technologies, constructions and patents. Next to that, the solar irradiation and crop growth underneath the panels were calculated with the help of models in order to calculate the financial revenue and profitability of the system.

Kale, chard, broccoli, peppers, tomatoes, and spinach were grown at various positions within partial shade of a solar photovoltaic array during the growing seasons from late March through August 2017 and 2018. The rows of panels were orientated north-south and tracked east to west during the daylight hours, creating three levels of shade for the plants: 7% of full sun, 55-65% of full sun, and 85% of full sun, as well as a full sun control outside the array. Average daily air temperature at canopy height was within +\- 0.5oC across the shade conditions. Over two field seasons, biomass accumulated in correction with the quantity of photosynthetically active radiation (PAR). Kale produced the same amount of harvestable biomass in all PAR levels between 55% and 85% of full sun. Chard yield was similar in PAR levels 85% and greater. Tomatoes produced the same amount harvestable biomass in all PAR levels greater than 55% of full sun. Broccoli produced significantly more harvestable head biomass at 85% than at full sun irradiance but required at least 85% of full PAR to produce appreciable harvestable material. Peppers generated harvestable fruit biomass at PAR of 55% of full sun or less, but yielded best at 85% of full sun or more. Spinach was sensitive to shade, yielded poorly under low PAR, but increased biomass production as PAR increased. Microclimate variations under PV arrays influence plant yields depending on location within a solar array. Adequate PAR and moderated temperature extremes can couple to produce crop yields in reduced PAR environments similar to and in some cases better than those in full sun. Results from our study showed that careful attention must be made when developing PV arrays over the crops and when choosing which crops to plant among the arrays.

Grasslands and croplands located in temperate agro-ecologies are ranked to be the best places to install solar panels for maximum energy production. Therefore, agrivoltaic systems (agricultural production under solar panels) are designed to mutually benefit solar energy and agricultural production in the same location for dual-use of land. However, both livestock farmers and energy companies require information for the application of efficient livestock management practices under solar panels. Therefore, this study was conducted to compare lamb growth and pasture production under solar panels and in open pastures in Corvallis, Oregon in spring 2019 and 2020. Averaged across the grazing periods, weaned Polypay lambs grew at 120 and 119 g/head/d under solar panels and open pastures, respectively in spring 2019 (P=0.90). Although a higher stocking density (36.6 lambs/ha) at the pastures under solar panels was maintained than open pastures (30 lambs/ha) in the late spring period, the liveweight production between grazing under solar panels (1.5 kg ha/d) and open pastures (1.3 kg ha/d) were comparable (P=0.67). Similarly, lambs liveweight gains and liveweight productions were comparable in both pasture types (all P>0.05). The daily water consumption of the lambs in spring 2019 were similar during early spring, but lambs in open pastures consumed 0.72 l/head/d more water than those grazed under solar panels in the late spring period (P<0.01). However, no difference was observed in water intake of the lambs in spring 2020 (P=0.42) The preliminary results from our grazing study indicated that grazing under solar panels can maintain higher carrying capacity of pasture toward summer, and land productivity could be increased up to 200% through combining sheep grazing and solar energy production on the same land. More importantly, solar panels may provide a more animal welfare friendly environment for the grazing livestock as they provide shelter from sun and wind.

Agrivoltaic systems are designed to mutually benefit solar energy and agricultural production in the same location for dual-use of land. This study was conducted to compare lamb growth and pasture production from solar pastures in agrivoltaic systems and traditional open pastures over 2 years in Oregon. Weaned Polypay lambs grew at 120 and 119 g head−1 d−1 in solar and open pastures, respectively in spring 2019 (P = 0.90). The liveweight production between solar (1.5 kg ha−1 d−1) and open pastures (1.3 kg ha−1 d−1) were comparable (P = 0.67). Similarly, lamb liveweight gains and liveweight productions were comparable in both solar (89 g head−1 d−1 ; 4.6 kg ha−1 d−1) and open (92 g head−1 d−1 ; 5.0 kg ha−1 d−1 ) pastures (all P > 0.05) in 2020. The daily water consumption of the lambs in spring 2019 were similar during early spring, but lambs in open pastures consumed 0.72 L/head−1 d−1 more water than those grazed under solar panels in the late spring period (P < 0.01). No difference was observed in water intake of the lambs in spring 2020 (P = 0.42). Over the entire period, solar pastures produced 38% lower herbage than open pastures due to low pasture density in fully shaded areas under solar panels. The results from our grazing study indicated that lower herbage mass available in solar pastures was offset by higher forage quality, resulting in similar spring lamb production to open pastures. Our findings also suggest that the land productivity could be greatly increased through combining sheep grazing and solar energy production on the same land in agrivoltaics systems.

The combined use of solar photovoltaics and agriculture may provide farmers with an alternative source of income and reduce heat stress in dairy cows. The objective of this study was to determine the effects on grazing cattle under shade from a solar photovoltaic system. The study was conducted at the University of Minnesota West Central Research and Outreach Center in Morris, Minnesota on a grazing dairy. Twenty-four crossbred cows were randomly assigned to 2 treatment groups (shade or no shade) from June to September in 2019. The replicated (n = 4) treatment groups of 6 cows each were provided shade from a 30-kW photovoltaic system. Two groups of cows had access to shade in paddocks, and 2 groups of cows had no shade in paddocks. All cows were located in the same pasture during summer. Behavior observations and milk production were evaluated for cows during 4 periods of summer. Boluses and an eartag sensor monitored internal body temperature, activity, and rumination on all cows, respectively. Independent variables were the fixed effects of breed, treatment group, coat color, period, and parity, and random effects were replicate group, date, and cow. No differences in fly prevalence, milk production, fat and protein production, or drinking bouts were observed between the treatment groups. Shade cows had more ear flicks (11.4 ear flicks/30 s) than no-shade cows (8.6 ear flicks/30 s) and had dirtier bellies and lower legs (2.2 and 3.2, respectively) than no-shade cows (1.9 and 2.9, respectively). During afternoon hours, shade cows had lower respiration rates (66.4 breaths/min) than no-shade cows (78.3 breaths/min). From 1200 to 1800 h and 1800 to 0000 h, shade cows had lower body temperature (39.0 and 39.2°C, respectively) than no-shade cows (39.3 and 39.4°C, respectively). Furthermore, between milking times (0800 and 1600 h), the shade cows had lower body temperature (38.9°C) than no-shade cows (39.1°C). Agrivoltaics incorporated into pasture dairy systems may reduce the intensity of heats stress in dairy cows and increase well-being of cows and the efficiency of land use.