320 ITU‐T's Technical Reports and Specifications 3.7.1 Home energy management Visualization service of consumed energy The system is required to measure the consumed electric energy of each distributer, breakers the generated energy by solar cells, and allow to calculate the fee of energy and to inform the cable customer of the result. The current sensor is required to transmit measured data (consumed or generated electric power) to the radio terminal device by ZigBee or wireless fidelity (Wi‐Fi) radio chip. The residential gateway (RGW) is required to store the data temporarily (e.g., for one day) and to upload the data to the collection server of sensor information. The system is also required to present the cable customer with a regional power saving period, a power saving announcement, and information on power balance from a municipal office or power company. In other words, the system should not only display consumed/generated power. The system can provide, optionally, recommend services for power and cost saving, in line with the customer's power consumption pattern. Furthermore, the system can optionally provide any additional support including regional ranking information of power saving or additional incentive services. The system is required to be operated on RGW at home and on a smart phone or tablet terminal, and in an outdoor environment through the cable portal function. The system is required to send the information by e‐mail to the assigned address. Figure 78 – RGW and related entities for home ICT services Source: Technical Report of the Focus Group on Smart Cable Television. Solar power cell maintenance service This is an information service to the cable customer on the maintenance of the solar power cell. The system is required to report to the cable customer the necessity of surface cleaning, the existence of malfunction through the monitoring of past power generation record and comparison with regional standard generation value.