The intent of this report is to help qualified individuals maintain and inspect PV systems safely. Qualification to conduct such inspections is earned by direct on-the-job training under qualified supervision or through training programs offered by accredited educational institutions or manufacturers. It should be noted that many testing and maintenance activities require two people to be performed safely and efficiently. Currently, an employee who is being trained for a task, demonstrates the ability to perform duties related to that task safely, and is under the direct supervision of a qualified person is usually considered to be a qualified person. As the number of U.S. PV installations grows, the industry will increasingly focus on O&M. PV systems have multi-decade lifetimes, and regular O&M helps optimize an installation’s ROI over its life. There are currently three working groups focused on this issue, and they will develop a more comprehensive O&M approach in the next few years. In the meantime, this report serves as an introduction to O&M for PV installations. The conclusions of this introductory report include: To maintain quality control and safety standards, it is important that only qualified personnel work on PV installations. It is not always easy, however, to identify qualified personnel. The authors suggest skill and knowledge guidelines for PV technicians in the Qualified Personnel section of the INTRODUCTION chapter; Safety is a serious concern when servicing PV installations. Early PV systems often had maximum system voltages less than 50 Vdc, but 600 Vdc systems are now common, and 1,000 Vdc systems are allowed by code in commercial and large-scale installations. Safety considerations require that qualified personnel use properly rated equipment and be trained for servicing the higher voltage systems; Qualified personnel should always work in teams of two people when working on live equipment. In addition, on a given jobsite, there should always be at least two qualified persons trained in CPR; Not all installations have appropriate signage, and qualified persons must be trained to recognize potential hazards with or without signage present; System uptime and availability is a key objective of O&M. Inverters that are offline can have a dramatic negative impact on the ROI of a PV system. Inverter failure rates are important to ROI, but even more important than how often an inverter goes offline is how quickly it can be placed back into service; Low power production also impacts ROI, and O&M personnel need effective strategies for identifying and correcting problems quickly. One specific recommendation is to stock critical parts that have long supply lead times.
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.
Irrigation helps grow agricultural crops in dry areas and during periods of inadequate rainfall. Proper irrigation could improve both crop productivity and produce quality. For high density apple orchards, water relations are even more important. Most irrigation in tree fruit orchards is applied based on grower’s experience or simple observations, which may lead to over- or under-irrigation. To investigate an effective irrigation strategy in high-density apple orchard, three irrigation methods were tested including soil moisture-based, evapotranspiration (ET)-based and conventional methods. In soil moisture-based irrigation, soil water content and soil water potential sensors were measured side by side. In ET-based irrigation, daily ET (ETc) and accumulated water deficit were calculated. Conventional method was based on the experience of the operator. The experiment was conducted from early June through middle of October (one growing season). Lastly, water consumption, fruit yield and fruit quality were analyzed for these irrigation strategies. Results indicated that the soil moisture-based irrigation used least water, with 10.8% and 4.8% less than ET-based and conventional methods, respectively. The yield from the rows with the soil moisture-based irrigation was slightly higher than the other two, while the fruit quality was similar. The outcome from this study proved the effectiveness of using soil moisture sensors for irrigation scheduling and could be an important step for future automatic irrigation system.
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.
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.
Foldable solar cells, with the advantages of size compactness and shape transformation, have promising applications as power sources in wearable and portable electronics, building and vehicle integrated photovoltaics. However, in contrast to mild bending with curvature radius of several millimeters, folding generates the crease with extreme curvature radius of sub-millimeter, resulting in the appearance of large strain and stress. As a result, it is highly challenging to realize robustly foldable and highly efficient solar cells. Here, we summarize the recent progress on photovoltaic performance and mechanical robustness of foldable solar cells. The key requirements to construct highly foldable solar cells, including structure design based on turning the neutral axis plane, and adopting flexible alternatives including substrates, transparent electrodes and absorbers, are intensively discussed. In the end, some perspectives for the future development of foldable solar cells, especially the standard folding procedure, improvement in the folding endurance through revealing failure mechanisms, are provided.
In this paper, a novel UGV (unmanned ground vehicle) for precision agriculture, named “Agri.q,” is presented. The Agri.q has a multiple degrees of freedom positioning mechanism and it is equipped with a robotic arm and vision sensors, which allow to challenge irregular terrains and to perform precision field operations with perception. In particular, the integration of a 7 DOFs (degrees of freedom) manipulator and a mobile frame results in a reconfigurable workspace, which opens to samples collection and inspection in non-structured environments. Moreover, Agri.q mounts an orientable landing platform for drones which is made of solar panels, enabling multi-robot strategies and solar power storage, with a view to sustainable energy. In fact, the device will assume a central role in a more complex automated system for agriculture, that includes the use of UAV (unmanned aerial vehicle) and UGV for coordinated field monitoring and servicing. The electronics of the device is also discussed, since Agri.q should be ready to send-receive data to move autonomously or to be remotely controlled by means of dedicated processing units and transmitter-receiver modules. This paper collects all these elements and shows the advances of the previous works, describing the design process of the mechatronic system and showing the realization phase, whose outcome is the physical prototype.
Plant pest spraying machines are now starting to develop using a variety of technologies ranging from diesel to electric power. However, this technology has problems such as limited fuel capacity in diesel engines and a lack of electricity demand for electric batteries. If the sprayed area is too large, the capacity for fuel and battery requirements is insufficient. In this study, we will explain how to apply solar cells to make a plant pest spraying machine so that when spraying will occur simultaneously the process of charging or charging the battery by solar power. So that the need for battery capacity is met for spraying over a large area. The process of making this tool is done by assembling several components such as solar panels, SCC (solar charge controller), spray tanks and lithium batteries.
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Harvesting the Sun, the Agrisolar Short Film, is Available Now!March 20, 2024 - 5:52 pm
Case Study: Alaska AgrivoltaicsMarch 20, 2024 - 10:07 am
