A cloud-based home electricity data-monitoring system, which is based on an Arduino Mega controller, is proposed for monitoring the electricity consumption (electrical power) and power quality (PQ) in home. This system is also capable of monitoring the fundamental frequency and supply-voltage transients to ensure that the appliances operate in a safe operation range. The measured data (voltage and current) are transmitted through a WiFi device between the Arduino controller and server. The transmission control protocol (TCP) server is set up to acquire the high-data transmission rate. The server system immediately displays the calculated parameters and the waveform of the acquired signal. A comparison with a standard measurement device shows that the proposed system, which can be built at a low cost, exhibits the same functions as a factory product.