National Solar Car Challenge

The Plano Green Team is a high school Solar Car Team working on building a car that runs on solar power. Every year we race our car and compete against hundreds of other high school teams, as a part of The Solar Car Challenge.

1. Introduction

Solar-powered vehicles represent a cutting-edge fusion of renewable energy and automotive engineering. As part of a high school solar car team, I took on the challenge of redesigning critical systems to maximize our vehicle's performance during competition. My responsibilities included overhauling the solar panel array wiring, re-engineering the auxiliary electrical systems, and developing a telemetry system for real-time data monitoring. This paper presents the methods, processes, and outcomes of these efforts, highlighting the technical skills and teamwork required to achieve our goals.

2. Redesign of the Solar Panel Array Wiring

One of the primary tasks I undertook was the complete redesign of the solar panel array wiring. The existing wiring system was inefficient and prone to energy loss, which compromised the car's performance. I began by meticulously mapping the existing connections and identifying areas where energy transfer could be optimized. The goal was to ensure maximum efficiency in transferring energy from the solar panels to the battery storage and the car's power distribution system.

After analyzing the shortcomings of the previous system, I implemented a new wiring design using Anderson connectors. These connectors allowed for modular and reconfigurable connections, significantly improving the flexibility and reliability of the system. The new setup enabled more efficient energy transfer to the Maximum Power Point Trackers (MPPTs), solving a key problem from previous races. This redesign required careful attention to detail to prevent potential short circuits and inefficiencies, ultimately resulting in a more robust and efficient electrical system.

3. Re-engineering of the Auxiliary Electrical Systems

In addition to the solar panel array, I was responsible for re-engineering the car's auxiliary electrical systems, which included critical components such as turn and brake lights, the horn, and the dashboard. The primary focus was on reducing power consumption and improving the reliability of these systems, ensuring they operated independently of the main battery pack.

I collaborated with a teammate to update the system’s schematics and recode its operations to align with the new design. We decided to power the auxiliary systems with a separate battery, thereby reducing the load on the main battery and conserving energy for the race. We also designed and 3D-printed a new dashboard to house the controls for these systems, ensuring easy access and improved functionality for the driver.

Our work on the auxiliary systems required not only technical skills but also a deep understanding of the car's overall power management. Through testing various configurations, we identified the most effective setup, resulting in a more reliable and efficient system that contributed to the car's improved performance during the competition.

4. Development and Implementation of a Telemetry System

Recognizing the importance of real-time data in optimizing race performance, I took the initiative to develop and implement a telemetry system for the solar car. This system was designed to monitor key parameters such as battery voltage, current flow, watt-hours, and vehicle speed, and transmit this data wirelessly to our pit crew.

Given the tight timeline, I focused on creating a functional yet straightforward system. The final design included a 3D-printed housing with monitors displaying critical data points. I integrated a communication system using a cell phone, which remained on a video call with the pit crew throughout the race, allowing me to relay data and make real-time adjustments as needed.

Although the telemetry system was developed under significant time constraints, it played a crucial role in our race strategy. The experience of designing and implementing this system deepened my understanding of data acquisition and communication, skills that are essential in both engineering and competitive racing environments.

Future Work: Advancing the Telemetry System with CAN-Bus Integration

Where We Are Today

The current telemetry system in our solar car relies on a video feed to monitor and relay data from the car's components to the pit crew. While this method provides real-time information, it is far from ideal. The reliance on a video feed introduces potential reliability issues, such as signal loss or image distortion, which can compromise the accuracy of the data and the effectiveness of our race strategy. Moreover, this system is manual and difficult to automate, limiting its scalability and efficiency.

Possible Solutions

To address these limitations, I have been researching the implementation of a Controller Area Network (CAN) bus system, a technology widely used in modern automotive applications. The CAN-bus system offers a robust and automated solution for data transfer, enabling real-time communication between individual devices and components within the car and a central cloud service. This setup would allow the pit crew to access data from anywhere, providing a significant advantage during races.

The CAN-bus system functions by using specialized adapters to interface with each device on the car, recording data such as battery voltage, current flow, and vehicle speed. All the collected data is then compiled into a singular data packet, which is transmitted to a central hub. With the integration of an onboard Wi-Fi router or cellular hotspot, this data packet can be uploaded to a cloud server, making it accessible to the pit crew in real time. The system’s universal compatibility with various automotive components would allow us to gather more comprehensive data from a wider range of sources within the car.

Issues with the Proposed Solution

Despite the promising advantages of the CAN-bus system, there are significant challenges that must be addressed. The most pressing issue is the compatibility of the Maximum Power Point Trackers (MPPTs) currently used in our car. These MPPTs are outdated and do not support CAN-bus adapters, rendering them incompatible with the proposed system. This limitation is a critical obstacle, as the MPPTs play a crucial role in managing the car's solar energy conversion and battery charging processes.

Upgrading the MPPTs to a model compatible with CAN-bus technology would be an ideal solution, but this option comes with its own set of challenges. The cost of new MPPTs could strain the team's budget, and the time required for integration and testing could disrupt our preparation for upcoming competitions. Additionally, there may be unforeseen technical issues during the transition to a new system, which could impact the overall performance and reliability of the car.

Conclusion

The CAN-bus system presents a highly promising path forward for our solar car's telemetry needs, offering enhanced data collection, automation, and real-time accessibility. However, its implementation is not without challenges, particularly regarding compatibility with our current MPPTs. Moving forward, careful consideration will be given to the costs and benefits of upgrading the MPPTs or exploring alternative solutions to achieve the desired functionality. As we continue to innovate and refine our approach, the ultimate goal remains to enhance our car’s performance and ensure success in future competitions.