Solar Tracking using Smartphone Mobile Apps

1.0 Background

While roof-mounted solar systems are considered a good idea to be implemented on the camper van to generate electricity sustainably, there will be a detrimental effect on the overall efficiency of the system because the solar panels will not always be directly facing the sun. To solve this weakness, our project aims to develop an open-loop control system, that involves the sunlight incident angle measurement, to adjust the elevation angle of a solar panel along a single rotational axis.

2.0 Objective

Our project aims to develop a low-cost, sustainable and easily replicable open-loop solar panel control system, that is equipped with a smartphone app to measure the angle of incident sunlight, which allows the user to adjust the solar panel elevation angle along the horizontal axis. This system is also designed in such a way that can benefit the camper driver as they could just use the smartphone app to control the elevation of the solar panel without the need to adjust it manually.

3.0 Literature Review

For the past many years, solar systems with static positions have been used, however, it has been proven in many journals that a single or dual-axis solar tracker can increase the energy yield by the solar panel. Research done by Deekshith et al. which investigated the efficiency yield via single and dual-axis solar tracking systems using Arduino control systems with servo motors proves to be effective in terms of energy-yielding as well as having low installation costs in areas with a low horizon and shade-free from dawn to dusk [1,4].

Moreover, solar tracker systems with appropriate control systems which utilise both chronological algorithms and active control systems developed by Bouche et al. can increase electrical power harnessed by the photovoltaic cell by 22-56% [2]. Furthermore, open-loop solar tracking systems have been proven to be the cheapest and simplest tracking system compared to closed-loop tracking systems, hence suitable for outdoor applications, such as installing on a camper van [3].

4.0 Methodology

The proposed design requirements for the solar tracker mechanism have to satisfy certain conditions which are as follows:

1. It should be reliable and able to withstand harsh weather conditions such as changes in humidity, extreme temperature as well as dust. This is because solar panels mounted on camper vans are usually mounted on the van's rooftop.
2. It should consume the minimum power required to run the servo motor for rotation motion, to ensure sustainability in the net energy produced from the solar panel.
3. Since solar panels are required to achieve carbon neutrality in the energy sector, solar panels will be required to be easily obtainable by consumers, therefore another design requirement for the solar tracker mechanism is to have the optimum performance-to-cost ratio which should give good results with a small investment.
4. The components used for the solar tracker systems should be easily sourceable hence, an Arduino microcontroller, an MG946R servo motor, LDRs and a Bluetooth module is used in the tracker system.
5. Since the solar tracker system is decided to be an open-loop system, a user-friendly GUI is also developed, such that users can have easy access and control of the tracker system.

By considering the design criterion stated above, a light sensor circuit is implemented. Various light-dependent resistors (LDR) are installed to face different directions, so they can detect the light intensity from multiple angles. Since the resistance of LDR always decreases in bright conditions, thus the resistance value will be inversely proportional to the light intensity. With simple potential divider circuits, the analogue voltage value of each LDR could be taken and compared, such that the optimum angle of rotation would be towards the best orientation.

For the circuit, a single Arduino Board is used as the main control unit, which serves to power and rotates the servo motor to the desired angle. The Arduino converts the analogue signal of LDR into digital readings. A Bluetooth module was attached to the Arduino to help transmit data and receive information from the smartphone, allowing for a user-friendly method of changing the elevation angle of the solar panel. The user will receive angle data on the smartphone, and when the user chooses to turn the panel, the data will be transmitted back to the Arduino through the Bluetooth module. The controller is programmed to store data in memory (EEPROM) and load it on successive boot-ups, and this ensures that the solar panel retains its previous state (angle) which prevents it from jerking off the servo motor.

Extending from the mobile application, the prototype was created using MIT Inventor App. It enables easy connection with the Bluetooth device from Arduino. The features are as shown as follows:

Below is the main algorithm of the data transmission:

At every clock cycle, the Bluetooth device is checked to see if it is connected. Then, if the transmission occurs (there are bytes available to receive), the global variable will be set to the transmitted data. Then, data will be processed accordingly.

To ensure that it is user-friendly, an SMS will be sent to the user whenever the solar panel needs to be titled in a new direction, as shown in the figure below.

5.0 Results and Discussions

In this experiment, the solar tracking app was tested to determine its effectiveness in optimizing solar panel positioning and increasing energy output. The experiment involved comparing the energy output of a fixed solar panel versus a solar panel that has been optimized using the app.

The light was directed from one specific direction to the solar panel. It was seen that there was not much power. However, after using the light sensor to detect the maximum light, the solar panel turned in the right direction and the power output increased from 7.9 V to 13.9 V, which nearly doubled the value.

6.0 Conclusion

In conclusion, a solar tracking app can be a valuable addition to a solar energy project as it can help optimize the energy output of solar panels. By tracking the movement of the sun, the app can adjust the position of the panels to maximise the amount of solar irradiance throughout the day to generate a high amount of electricity. This can result in increased overall energy efficiency and also cost savings in generating power. Based on our experiment, the output voltage of the solar panel has increased by nearly 200% per day by being equipped with solar tracking capability.

To sum up, integrating a solar tracking app into a solar energy project can enhance its efficiency and lead to better returns on investment. Nevertheless, the app's effectiveness will rely on several factors, including the technology's quality, data accuracy, and user involvement. Thus, conducting extensive research and testing is crucial before implementing the app into the project. Nonetheless, the solar tracking app has demonstrated that it can be a practical and visionary solution to preserve and safeguard the environment by improving the efficiency of sustainable power generation, which can replace non-renewable energy sources.

7.0 References

1. Awasthi, A. et al. “Review on Sun Tracking Technology in solar PV system,” Energy Reports, 6, 2020, pp. 392–405.
2. Baouche, F.Z. et al. “Design and simulation of a solar tracking system for PV,” Applied Sciences, 12(19), 2022, p. 9682.
3. Al-Naima, F.M. and Yaghobian, N.A. “Design and construction of a solar tracking system,” Solar & Wind Technology, 7(5), 1990, pp. 611–617.
4. Juang, J.-N. and Radharamanan, R. (2014) “Design of a solar tracking system for renewable energy,” Proceedings of the 2014 Zone 1 Conference of the American Society for Engineering Education [Preprint].