UTRGV / COLLEGE OF ENGINEERING AND COMPUTER SCIENCE / MECHANICAL ENGINEERING DEPARTMENT
TEAM 13: Design of a Solar Panel for use over Agriculture
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SDI Students (L-R) |
· Cesar N. Gurrusquieta · Jose T. Molina · Jaime A. Guerra · Fernando Ortiz · Bradley G. Oviedo
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Faculty Advisor(s) |
· Dr. Horacio Vasquez
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Course Instructors |
· Dr. Noe Vargas Hernandez · Mr. Greg Potter
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WHAT IS THE PROBLEM WE ARE TRYING TO SOLVE?
WHY IS THIS PROBLEM IMPORTANT?
LEARN MORE ABOUT OUR DESIGN PROCESS
Welcome to the Agrivoltaics project website! As team 13 of the senior design groups for Dr.Varga’s SPRING2023/FALL2023 class we are also known as the Horizon Technologies group! Our team consisting of 5 group members are Jose Molina, Cesar Gurrusquieta, Jaime Guerra, Fernando Ortiz, and Bradley Oviedo have put a good amount of work into this project throughout the year. The concept of our project is known as Agrivoltaics. The problem we tackled was to create a structure that would allow co-locating agriculture and solar energy into one land while providing several other benefits to farmers and crops. We designed a structure for farmers that would allow solar panels to be installed above crops while reducing heat stress from the sun to the crops underneath. Beside using land efficiently, this project provides several other benefits that include water conservation, increase in crop yield, panel cooling to increasing efficiency, and several other benefits. We hope that you enjoy this project as much as we did. Click on the Welcome Video below![nv1]
Watch the Welcome Video!
This video shows a brief overview of Agrivoltaics with permanent structures:
This video shows how Agrivoltaics could bring life to struggling farms:
There is a limited amount of land on the planet and only certain types of locations can be adequately designated for the solar energy and agricultural sectors. On top of this, with the increasing population, the demand for energy and food would also increase along with it. The question is, is there enough land to expand our current supply and meet the demands of the population? For this reason, our project aims to use the limited available land to co-locate solar energy and agricultural commodities. This addresses the possible energy and food crisis that our communities could face in the future. But wait! There’s more! Besides food and energy, what about water? The increased consumption and limited availability of water are also a concern for future generations. This project also aims to reduce the water consumption of crops as it limits sun exposure to the soil and develops a microclimate for the crops to also result in a better yield during harvest. And let’s not forget about the fact that this is renewable energy which would help in reducing greenhouse gases and help in preventing our climate from spiraling out of control. It also provides farmers with a new source of income to stay profitable in a competitive inflationary market. Therefore, we aim to design an economical and scalable structure that can be provided to underserved farmers throughout the valley with the use of a $2.2 million grant from the federal government provided to UTRGV.
Currently, the biggest demands in our country are food and energy. For food, there is roughly 895 million acres of land that is used for agricultural. For renewable energy, that number is roughly 74 million acres of land. If we can provide synergy between agriculture and photovoltaics, we would be able to tap into the land that is currently used solely for agriculture to produce energy for the country synergistically. Another arguably necessary resource required for all life on the planet is water. Through our research, we found there to be a light saturation point for plants which varies from different species of plants. This saturation point, after being reached, will cause the plant to release sweat and water which in turn requires a demand for more water needed for the crop growth.
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Photo 1: https://menokenfarm.com/unearthing-soils-benefits-from-cover-crops/
Photo 2: https://www.wired.com/story/kenya-gmo-approval/
As shown in the figures below the photosynthesis of a plant is affected by the amount of CO2 concentration in the atmosphere, the light intensity, and the temperature of the plant. As seen in figure 1, higher concentrations of CO2 in the environment lead to a greater requirement of light intensity for the plant and as seen in figure 2, the temperature for the most optimal photosynthesis increases and is more sensitive to the temperature. On the other hand, if there are lower concentrations of CO2 then the required light intensity decreases along with the optimal temperature the plant requires. It can also be seen in figure 1 that the plant only requires a certain amount of light intensity before additional light doesn’t have any effect on the photosynthesis.
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Figure 1 Runkle Erik, “Interactions of Light, CO2 and Temperature on Photosynthesis ”. Michigan State University department of horticulture ,2015.
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Figure 2 Runkle Erik, “Interactions of Light, CO2 and Temperature on Photosynthesis ”. Michigan State University department of horticulture ,2015.
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Bureau, while solar is growing rapidly in Texas, it is also replacing agricultural land to solar power generation [3]. Based on Tomascik(2021), $450 to $1200/acre/year is being offered to landowners throughout a 20 to 40 year lease with incremental increases for solar panel installations[3]. On the other hand, agricultural land is not only under threat of being replaced by solar energy companies but also urban developers. Figure 1 demonstrates the conversion of agricultural land to urban and highly developed (UHD), which includes solar installations, and low-density residential (LDR) land uses in red, while the solid green sections of the map indicate above median high-quality agricultural land. According to the map provided by the American Farmland Trust organization, the Rio Grande Valley has already lost approximately 50% of its high-quality agricultural land to urban development [8].
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Figure 3 From source [5] representation of suitable land for agriculture in green and yellow. |
Figure 4 A closer look at the Texan agricultural land and crop land lost to urbanization.
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Another major benefit of Agrivoltaics is the conservation of water with some Agrivoltaic systems from competitors stating to save up to 50% of water as seen with the Sun’Agri system. The water in Texas is mostly consumed by the energy, municipal, and agricultural sectors. As Bazer et al. state that “Texas risks a 41% (8.9 billion m3) water gap by 2070, due to projected 70% growth in population between 2020 and 2070, that will increase water demand by 17% and decrease water supply by 11%” [4]. Thanks to their analysis figure 2 demonstrates several of the water wells in Texas and the sector they are designated to be used for. In red, it shows fracking supply or water for energy use, green demonstrate water for food, and blue for domestic use. Just by viewing the figuring the Rio Grande Valley’s water wells are mostly used for irrigation and water supply faces less consumption by the other main sectors yet there are regions which experience water supply stresses.
Figure 5 From source [4] representing the hotspots that can face water supply issues in Texas.
Agrivoltaics has seen significant growth in the development of technology as well as the presence of one-stop shops for solar farming. Several companies are working to make Agrivoltaics more accessible, affordable, and easier on the customer. According to the Solar Energy Industries Association (SEIA), once ranking 1st in 2021, Texas now ranks 2nd in the U.S. for solar power generation. With the capacity of generating 16,173 MW of solar energy, and a projected growth of 36,092MW over the next 5 years. Accounting for 4.7% of the state’s electricity, there has been an investment of $19.1 billion in solar energy in the state.
Photo: https://agecon.ca.uky.edu/solar-farming-considerations
Current solutions for merging crops growth with energy generation is the Agrivoltaic system, but that does require additional design. According to an article by Carlos Toledo, some key elements that farmers struggle to accommodate with solar farms is minimizing shadows on crops, maximizing electric energy generation, and landscape dimensions and mobility. Several current solutions for this sector have been developed by companies like REM TEC, Sun’R/Sun’Agri, and Insolight. Each of these companies provides a different design for Agrivoltaic structure.
REM TEC
The company proves to have increased yield by 4.3% for maize while not involving any significant yield increase for certain crops. The first set of design configurations consists of a biaxial system placed 5m above the ground. Tracker 10 consists of 10PV modules, produces between 2.5 to 4.35KWP, and has a length of 12m; while Tracker 2.1 consists of 24PV modules with 78 cells, produces up to 16.8KWP, and has a length of 14m. The second design consists of a suspended system 5m above the ground. It allows easy transit of all the machines used in agriculture, adapts to different soils as it can resist a slope of 15%. The distance between the poles can be up to 25m, distance between rows 6m, and the panel configuration can be chessboard or linear producing up to 830KWP/HA. https://remtec.energy/en/agrovoltaico
Figure 6 a) Tracker 10 b) Tracker 2.1 c) Line Configuration d) Chessboard configuration
Sun’R/Sun’Agri
The company states that their system can lower temperatures to 5C in heat waves, reduces the risk of spring frost by increasing 1C to 4C at night for the crops, had 12% to 50% reduction in water use, improved the phenolic and delayed technological aromatic quality, giving alcohol content up to –2, increase in acidity between 9% to 14%, anthocyanin increase of 13%, and mutualized the structure to install irrigation and nets. The panels lie greater than 4m above the ground. The system consists of sensors that take in meteorological and plant physiological data to adjust the tilt of the panels autonomously. It also contains hail nets to protect the crops. https://sunagri.fr/notre-solution/technologie/
Insolight
The unique features of their translucent solar modules provide 30% to 50% more electricity generation. It allows the adjustment of the light to optimize crops’ growth over season and changing climate. Like the Sun’R model contains sensors to track plant physiology and maximize electricity production.
Translucency High-Efficiency in Agrivoltaics (THEIA) modules
The modules are a groundbreaking product for the agrivoltaics sector since besides being able to diffuse the light between the solar cells and plants, the solar cells have a 30% efficiency which is well above 21%, the highest efficiency rating for a solar panel. The panels are stated to have a light regulation yielding up to 75% of light transmission, can be mounted as easily as conventional solar panels and have had a 25-year reliability in the field. As can be seen in the image below the panel is integrated with optical micro-tracking technology that when aligned allows the optical lenses to concentrate the light on the solar cells in the lower plane and when unaligned allows the transmission of light to the plants. They state that 30%-160% more energy is produced per meter squared while increasing crop yield, eliminating the tradeoff between electricity and agriculture production, and allowing for 100% densification. The return on investment is stated to occur in 8 years.
Photo: https://nsci.ca/2019/12/05/agrivoltaics-what-is-it-and-how-does-it-work/
Our main motivation to work on this agrivoltaic project is the ever-growing need for more food, water, and energy with our growing population. As the population increases, we are needing more food to meet the needs of each household. Our mission is to make farms more efficient by increasing yield from crops. While doing so, we will be conserving a portion of the water that was previously needed to grow those crops. Our agrivoltaic project would also allow us to take land that was only serving one purpose and transform it into a multifaceted multiuse area. The project would allow us to transform crop lands into energy-generating solar farms, while still providing mobility and flexibility to farmers.
Photo: https://www.renewableenergyworld.com/news/doe-offers-funding-to-scale-agrivoltaics-projects/#gref
After understanding the importance of merging agricultural land with energy generation in depth, we explored various potential solutions and selected the best concept. Our solution was to design a mobile solar panel system that allows for sunlight to pass through to crops at calculated intervals while still generating energy through solar capture. The structure will have a series of solar panels with a rotating mechanism. This will allow for sunlight to pass through to the ground when the solar panels are turned vertically, and for sunlight to be captured by solar panels when they are turned horizontally. This structure will allow for crops to get the recommended amount of sunlight before reaching their threshold. Under traditional farm conditions, the plants absorb too much sunlight, and their sweat threshold is reached. This causes the plants to begin to sweat their stored water, which leads to an increase in water needed for continued growth. Our design would allow for crops to get just enough sunlight to grow, while reducing their exposure to excess sunlight.
Photo: https://metsolar.eu/blog/what-is-agrivoltaics-how-can-solar-energy-and-agriculture-work-together/
Once we defined a clear solution idea (i.e. concept), we applied our engineering knowledge to transform it into a real product. These were some of the important design challenges and how we approached each one of them:
1. Maintaining our structure within budget
While an Agrivoltaics structure can consist of more than 10 solar panels mounted on it, we decided to keep our prototype to 3 solar panels to stay within our budget. With the cost of the solar panels already taking a significant amount of money out of our budget, a three-panel structure would also reduce the amount of L-channels and square channels needed for assembly. While aluminum channels would have been a better option to reduce weight and manage corrosion, we decided to use low carbon steel for our structure as the most economical option and bought it from a local supplier to eliminate shipping costs. Each team has
2. Reducing torque requirement of motor
Since our prototype involves tracking the sun, an actuator must be involved in rotating the shaft of the rail mounts to point the solar panels towards the sun as it moves. In this case, we decided to go with a single shaft self-locking reversible worm gear motor as our actuator. We also determined the location of the center of gravity of the rail mounts and added channels to be able to rotate the shaft about the center of gravity. This would reduce the motor torque requirement as there should be virtually no counter torque as the CG is at the center of rotation. The center of gravity was calculated to be 1.72” from the top of the solar panel, this aligns the center of the rotating shaft with center of gravity so that the minimum amount of torque is required to rotate the shaft.
3. Maintaining the rail mount shaft stationary
Our next challenge was figuring out how to maintain the rail mount from rotating on its own. For this we figured that using a worm wheel and worm gear configuration would allow the worm gear to hold on to the worm wheel and prevent the shaft from rotating. Placing the center of ration along with the center of gravity of the rail mount also helped in prevent rotation.
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4. The structure must be stable in windy conditions.
For the anchoring of the system, it was found that an anchoring screw would be the most effective way of anchoring the system to the ground. The structure will be anchored to the ground using 8 ground screw anchors, two for each leg, which will be sufficient in holding the system firmly to the ground.
5. Solar tracking to increase energy production.
Our solar tracking system does not require programming and is based more on the logic of the HD-36 Solar Tracking Controller which measures the light intensity from two photoresistors and inverses the polarity of the motor if required depending on the location of the sun. A buck converter steps down the voltage from the battery provided to the sensor.
We found that physical prototyping was extremely helpful to increase our understanding of the problem and the feasibility of our solutions. Our first prototypes were simple but useful and we continued evolving into more complex ones. Where we eventually ended up taking some of the most useful ideas from the prototypes we had made and combined them to end up with the final prototype.
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These designs were our first prototypes. The first designs were 3D printed at home; it gave the team an idea how to collaborate the system to be functional, collapsible, and easy to assemble.
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After much work, this is our final product:
The evolution of our concept variants demonstrates an interest in 4 post design structures. This variant provides the best overall stability by having 4 points of contact with the ground, which in turn will reduce the cross-sectional area for each post. With high wind forces being the most common in Rio Grande Valley, it is important that the structure can tolerate large lifting forces and that it won't detach from the ground. Hence, smaller lightweight beams will be used instead of larger heavier beams that would be required for 2 or 1 post structures. Another important design feature is ease of use and assembly; with a less complicated design, the structure will be easy to maintain and will require little to no human interaction except when changing the panel angle tilt or dusting the panels. Simplicity, cost efficiency, and practicality were the key factors in coming up with the final design.
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After having made our first prototype, we found that it takes a considerable amount of time to machine it, has too much weight and bolts/nuts , and is not scalable. For these reason, we have been working on the idea of our second prototype which will reduce manufacturing time, reduce overall weight, and allow scalability. This new idea incorporates the use of stainless steel tension ropes, thin flexible solar panels that can be up to 50% lighter than the conventional ones, and helical pier anchors to ground the structure to the earth. We have also looked into the idea of making it easier to raise the panels as can be seen in figure x and y.
Once the structure is assembled, we plan to test different angles of solar panel adjustment for solar energy absorption through various angles. Other structures will be analyzed; we understand that land size for structure placement may vary from user to user, so we are prepared to accommodate the customer to their needs. Overall, we plan to continue improving our structure for customer use, as we try to think like a customer to best accommodate the structure to their needs.
IN CONCLUSION
This project's purpose was to design a structure for anyone who wants to get involved with renewable energy and agriculture. Applying engineering analysis to the structure as a team was difficult, difficulty came with different options that the structure can offer. After evaluating what each individual team member brought to the table. We were able to change the project's direction to be more productive as a team. We understood that communication is important in our career, although everyone has a busy schedule, we were able to set our differences aside and become one as a team. After several meetings, we were able to better understand each other's point of view, we analyzed each member's strong attributes and assigned them their part of the project. Overall, we were able to overcome obstacles during this semester and continue to grow our communication skills and structure to give the best quality product. The completed prototype meets all the requirements that we wanted to achieve for the project, with the inclusion of the solar tracking system the panels will track the sun throughout the day.
REFERENCES
1. [1]Gonzalez, Mariah.”UTRGV receives $2.2M grant for ‘Climate-Smart’ Commodities project.”(2022): https://www.utrgv.edu/newsroom/2022/12/12-utrgv-receives-22m-grant-for-climate-smart-commodities-project.htm
2. [2]USDA,2020,”Agrivoltaics:ComingSoontoaFarmNearYou”: https://www.climatehubs.usda.gov/hubs/northeast/topic/agrivoltaics-coming-soon-farm-near-you
3. [3]Tomascik, Julie,“Solar panels crop up across Texas, divide rural communites.”(2021): https://texasfarmbureau.org/solar-panels-crop-up-across-texas-divide-rural-communities/
4. [4] Daher,Bassel et al.”Towards bridging the water gap in Texas: A water-energy-food nexus approach.” Science of The Total Environment Vol.647No.10(2019):pp449-463.DOI 10.1016
5. [5]
6. TexasAgStats.(n.d.).Www.texasagriculture.gov. https://www.texasagriculture.gov/About/Texas-Ag-Stats
7. Texas A&M AgriLife Research and Extension Center at Weslaco | Teaching, Research, Extension and Service. (n.d.). Weslaco.tamu.edu. Retrieved February 12, 2023, from http://weslaco.tamu.edu/
Agricultural Water. (2019). CDC. https://www.cdc.gov/healthywater/other/agricultural/index.html
9. https://alcobrametals.com/telescopic-tubing/
10. https://www.gosolartexas.org/solar-equipment#typesofpvpanels
11. https://solardesignguide.com/solar-panel-tilt-and-azimuth/
12. [17]Ahmad, Mukhart.”Photovoltaic Systems.” Operation and Control of Renewable Energy Systems. John Wiley & Sons Incorporated, Hoboken (2017)
13. [13] Toledo, C.; Scognamiglio, A. Agrivoltaic Systems Design and Assessment: A Critical Review, and a Descriptive Model towards a Sustainable Landscape Vision (Three-Dimensional Agrivoltaic Patterns). Sustainability 2021, 13, 6871. https://doi.org/10.3390/su13126871
14. TrackerSled. (n.d.). Trackersled. TrackerSled. Retrieved February 11, 2023, from https://trackersled.com/
15. SunPower. (2023, January 3). Home solar panels, commercial & utility-scale solar solutions. SunPower. Retrieved February 11, 2023, from https://us.sunpower.com/
16. Sun'Agri. (2021, September 20). Technologie. Sun'Agri. Retrieved February 13, 2023, from https://sunagri.fr/notre-solution/technologie/
17. OCI Solar Power. (2019). Solar developer, San Antonio, TX. OCI Solar Power. Retrieved February 11, 2023, from https://ocisolarpower.com/
18. NextEra Energy. (2023). A real plan for real zero. NextEra Energy | Real Zero. Retrieved February 12, 2023, from https://www.nexteraenergy.com/real-zero.html?cid=SEANEE0013aug22&gclid=CjwKCAiAuaKfBhBtEiwAht6H79TPSHi03IU6010JUym4rw8cN8x13LNdeZIKYZuXMdgzE8pCifgSfhoCvowQAvD_BwE
19. Insolight. (2021). Insolight - Product. Insolight. Retrieved February 11, 2023, from https://insolight.ch/product/
20. Edera.digital. (n.d.). Rem Tec - La Soluzione per il Fotovoltaico legata all'Agricoltura. REM Tec - La soluzione per il fotovoltaico legata all'agricoltura. Retrieved February 11, 2023, from https://remtec.energy/en/agrovoltaico
21. Ecoplexus. (2022). ECOPLEXUS Solar Solutions. Ecoplexus. Retrieved February 11, 2023, from https://www.ecoplexus.com/
22. Avantus202. (2023). Industry-leading pipeline of Smart Power Plants: Avantus: Avantus. Avantus LLC. Retrieved February 11, 2023, from https://avantus.com/development
23. LONGi. (n.d.). The world's leading supplier of solar PV Solutions. Longi. Retrieved February 11, 2023, from https://www.longi.com/us/
24. CanadianSolar. (n.d.). CanadianSolar. Canadian Solar – Global. Retrieved February 12, 2023, from https://www.canadiansolar.com/
25. Q Cells. (2023). Main - Q Cells North America. Main - Q CELLS North America. Retrieved February 11, 2023, from https://qcells.com/us/
26. Surany, A. P. (2018, November 20). Reconfigurable Solar Array and Method of Managing Crop Yield Using the Same.
27. Nogier, A. (2017, May 4). Electricity Generation Method Adapted to Crops.
28. Agrawal, R., Bermel, P. A., & Perna, A. (2021, March 4). Orientation of Photovoltaic Modules to Minimize Intercepted Radiation in Photovoltaic Aglectric Systems.
29. Agrawal, R., Alam, M., & Tuinstra, M. (2022, May 19). Photovoltaic Structures for Use in Agriculture Farms.
30. YEHIA, I., MAGADLEY, E., & EILAN, M. (2022, September 15). Arrangement of Photovoltaic Panels and System for Optimizing Angular Positioning of Photovoltaic Panels in a Greenhouse .
Our design process consisted of 5 stages and began with the Problem identification where we identify a valuable opportunity. Then we move on to Problem Formulation where we clearly define the problem to solve. Thirdly is the conceptual design where we come up with ideas to solve the problem. Fourthly, the embodiment design is the stage where we realize the idea. Finally, the validation and testing is where we make sure our prototype works. noe.vargas@utrgv.edu
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1st Variant |
2nd Variant |
Final Variant |
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• 4 Legs • 4 Solar Panels (Monocrystalline) • Fixed Panels • Ground Screw Attachments
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• 4 Legs • 4 Solar Panels (Monocrystalline) • Adjustable Height • Collapsible (via. Fold) • Angle Adjustment (Panels) • Wheel & Ground Screw Attachments
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• 4 Legs • 3 Solar Panels (Monocrystalline) • Angle Adjustment (Panels) • Ground Screw Attachments
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Testing and Validation
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Beam Deflection Analysis • 4 Fixtures (1 on ech leg) • 388 lb load applied at each beam supporting shaft location
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Beam Deflection Analysis • 2 Fixtures • 259 lb load applied at each stress location
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Flow Simulation Setup:
Analysis Type: External
Exclusions:
· Cavities without flow conditions
· Internal Space
Wall Conditions: 0 roughness
Temperature: 293.2 K
Fluid: Air
Gravity (X-Axis): 9.81 m/s
Wind Velocity (Z-Axis): 100 m/s or 223 mph.
Mesh Level: 5
Mesh Type: Boolean
Boundary Conditions: None
Global Goals:
· Maximum Dynamic Pressure
· Total Pressure
· Maximum Force
· Maximum Normal Force
· Maximum Shear Stress
Cut Plots:
· Dynamic Pressure
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The team would like to acknowledge everyone who was involved in this project which include:
· Dr. Vasquez, for being our adviser and guiding us in the right direction from introduction to design process. We thank you for assisting in our progress with this project, we hope to give the best product that money can buy. Thank you for your time and patience.
· Dr. Alemedia, for giving additional funding for our project.
· Dr. Noe Vargas, MSE Gregory Potter, MSE Samantha Ramirez, and Dr. Rogelio Benitez. Thank you all for aiding in this process. Thank you.
· Hector Artiaga (machine shop boss) for giving us guidance on manufacturing methods, storage location for prototype, and materials.
· Cesar Gurrusquieta (Cesar Jr’s dad) for his hospitality and aid in cutting sections of a wide square channel.
· Armando (Cesar Jr’s grandpa) for lending us his workshop and tools to work on the project and guidance on tool usage.