The IHD is an indoor display device which can receive the electricity consumption and alarming from the smart meter and scroll display. Moreover, the IHD can send data requirement and relay connection request by pressing the button. Flexible communication mode is supported, P1 communication or wireless RF communication that can widely use with different energy measurement devices. Multiple type power supply can be used for it. The IHD has the advantage of plug and play, low cost, more flexibility. The users can check the electricity data, power quality in real-time in home.