Design and Construction of a Solid-State Relay-Based Home Automation System Using Bluetooth Communication

Background: Home automation technologies improve energy efficiency and convenience, and are increasingly accessible in Nigeria through low-cost Bluetooth-enabled microcontrollers. Local design and construction provides engineering training value and reduces importation costs. Aim: This project designed and constructed a solid-state relay-based home automation system using Bluetooth communication for control of household appliances via a smartphone. Methods: An HC-05 Bluetooth module was interfaced with an Arduino Uno to receive control commands from a custom Android application. Solid-state relays replaced conventional mechanical relays to reduce switching noise and improve longevity. The system was installed in a three-bedroom house in Enugu for a 30-day field evaluation. Results: All 6 appliance channels responded to commands with mean latency below 120 milliseconds within a 10-metre Bluetooth range. System reliability was 99.1% across 3,200 switching events. User satisfaction rating was 4.6 out of 5.0. Conclusion: The Bluetooth home automation system is reliable, user-friendly, and cost-effective. Integration of a Wi-Fi module for extended range and compatibility with smart home platforms is recommended for future development. Keywords: home automation, Bluetooth, solid-state relay, Arduino, smart home.