A compact solar-powered mobile charging system that uses solar energy to charge an 18650 lithium-ion battery and provides a regulated 5 V USB output for mobile charging, with Arduino Nano-based voltage monitoring and a 16×2 I2C LCD.
The Solar Mobile Charging Using Embedded System project demonstrates the integration of:
- Renewable solar energy
- Lithium-ion battery storage
- Battery charging and power conversion
- Embedded-system-based voltage monitoring
- LCD-based measurement display
- USB mobile charging
Solar Panel → 1N5819 Schottky Diode → TP4056 Charger → 18650 Li-ion Battery → Switch → MT3608 Boost Converter → 5 V USB Output → Mobile Charging
The Arduino Nano monitors the measured voltage through a voltage-sensor module connected to its analog input and displays the calculated voltage on a 16×2 I2C LCD.
- Design a solar-powered system capable of charging mobile phones.
- Store harvested solar energy in a rechargeable lithium-ion battery.
- Provide a regulated 5 V DC USB output.
- Monitor voltage using an Arduino Nano.
- Display the measured voltage on a 16×2 I2C LCD.
- Demonstrate the practical integration of renewable energy, power electronics and embedded systems.
- Develop a compact and low-cost prototype.
Component Purpose
☀️ 10 W Solar Panel Converts sunlight into electrical energy
1N5819 Schottky Diode Helps prevent reverse current toward the solar panel
TP4056 Charging Module Charges the single-cell Li-ion battery
18650 Li-ion Battery Stores harvested electrical energy
3-Pin Slide Switch Power/load switching
MT3608 Boost Converter Steps the battery voltage up to the required output
USB Output Provides the mobile-charging interface
Arduino Nano Reads the voltage sensor and drives the LCD
25 V Voltage Sensor Module Scales the measured voltage for the Arduino ADC
16×2 I2C LCD Displays the measured voltage
The prototype combines the solar panel, Schottky diode, TP4056 charging module, 18650 battery, MT3608 boost converter, USB output, voltage sensor, Arduino Nano and 16×2 I2C LCD.
The solar panel converts sunlight into DC electrical power.
The 1N5819 Schottky diode is used in the charging path to help prevent reverse current from flowing back toward the solar panel when solar generation is low or unavailable.
The solar-generated power is supplied to the TP4056 charging module, which is used to charge the single-cell 18650 lithium-ion battery.
The 18650 battery stores the harvested electrical energy.
The project report specifies:
- Nominal voltage: 3.7 V
- Full-charge voltage: 4.2 V
- Reported capacity: 5000 mAh
The MT3608 boost converter increases the battery voltage to the required output level. The system provides a regulated 5 V USB output for mobile charging.
The voltage-sensor module output is connected to Arduino Nano A0. The Arduino reads the analog value and calculates the corresponding input voltage.
The calculated voltage is displayed on the 16×2 I2C LCD.
The project uses Arduino IDE for programming and uploading the sketch to the Arduino Nano.
#include <Wire.h>
#include <LiquidCrystal_I2C.h>Function Arduino Nano Pin / Setting
Voltage Sensor Output A0 LCD SDA A4 LCD SCL A5 LCD I2C Address 0x27 LCD 16×2 I2C
The Arduino reads the analog value:
int adcValue = analogRead(sensorPin);It converts the ADC reading to Arduino-side voltage:
float adcVoltage = (adcValue * 5.0) / 1023.0;The code uses a voltage-sensor scaling ratio of:
const float voltageRatio = 5.0;The input voltage is calculated as:
float inputVoltage = adcVoltage * voltageRatio;The calculated voltage is:
- Displayed on the LCD with two decimal places.
- Printed to the Serial Monitor at 9600 baud.
- Updated every 500 ms.
The complete project sketch is available here:
The LCD displays the measured voltage in the following format:
Voltage:
3.92 V
The displayed value changes according to the voltage measured by the sensor.
The demonstration video is also included in this repository:
Solar_Mobile_Charging_Demo.mp4
Solar-Mobile-Charging-Using-Embedded-System/
│
├── README.md
│
├── code/
│ └── Solar_Mobile_Charging.ino
│
├── demo/
│ └── Solar_Mobile_Charging_Demo.mp4
│
├── docs/
│ └── Solar_Mobile_Charging_Report.pdf
│
└── images/
├── prototype.jpg
└── system_block_diagram.png
The project prototype was designed, developed and tested successfully.
The demonstrated system provides:
- Solar energy harvesting.
- Battery energy storage.
- Regulated 5 V USB output.
- Mobile-phone charging through the USB output.
- Arduino-based voltage measurement.
- LCD-based voltage display.
The project report states that the mobile phone began charging when connected to the USB output and that the output remained stable under the tested conditions.
- Eco-friendly renewable-energy source.
- Portable and easy to demonstrate.
- Can operate independently of grid electricity.
- Useful for outdoor and emergency situations.
- Low operating cost.
- Combines renewable energy with embedded-system technology.
- Provides a regulated USB charging output.
- Demonstrates practical power-electronics concepts.
Based on the project report and prototype:
- Charging speed depends strongly on sunlight.
- A single 18650 cell provides limited stored energy.
- The MT3608 conversion stage introduces efficiency losses.
- The system is not designed for modern fast-charging standards.
- Multiple conversion stages reduce overall efficiency.
- Prototype wiring can be improved for reliability.
- A proper enclosure would improve durability and protection.
Possible future improvements include:
Use multiple lithium-ion cells with an appropriate Battery Management System (BMS) to increase energy-storage capacity.
An MPPT (Maximum Power Point Tracking) based solar-charging system could improve solar-energy utilization.
Future versions could support modern charging technologies such as USB-C Power Delivery (PD).
The system could be expanded with IoT functionality for remote monitoring of:
- Battery voltage
- Solar output
- Charging status
- Overall system health
Temperature monitoring, short-circuit protection and additional over-voltage protection could improve safety and reliability.
A compact, rugged and waterproof enclosure would make the system more suitable for outdoor applications.
The complete academic report is available here:
📄
Solar_Mobile_Charging_Report.pdf
The report contains the project introduction, component details, software requirements, methodology, advantages, disadvantages, applications, results, future scope, conclusion and references.
Project Title: Solar Mobile Charging Using Embedded System
Department: Electronics and Communication Engineering
Institution: B.L.D.E.A's V.P. Dr. P.G. Halakatti College of Engineering and Technology, Vijayapur
University: Visvesvaraya Technological University (VTU)
Academic Year: 2025--26
- Sagar H. Beesanakoppa
- Sitaramasang Hunnur
- Sourabh V. Angadi
- Aditya Balul
Guide: Prof. Dr. Umesh Dixit
The academic report states that the project development involved:
- Component datasheets and specifications
- Google search resources
- YouTube tutorials
- Electronics reference websites
- Team discussions
- Faculty/project-guide guidance
- Arduino IDE
- Component suppliers and local electronic shops
This repository documents an academic mini project and its prototype implementation.
The current Arduino program performs voltage measurement and LCD/Serial display. Advanced features such as battery-percentage estimation, IoT monitoring, MPPT and fast charging are listed as future improvements unless separately implemented in the hardware and software.