# State of the Art and Trends Review of _Smart Metering_ in Electricity Grids
## 4 Development of _Smart Metering_ Worldwide  
The deployment of _SM_s is on the rise worldwide: around 1000 million _SM_s are expected to be installed worldwide by 2022 [45]. Figure 3 represents the evolution of _SM_ deployment worldwide from present to 2023. As discussed in Section 4, there is a wide range of available technologies and the most suitable one depends on a number of factors. The architecture of the electricity system highly influences the adopted approach for a _Smart Metering_ solution. Hence, the topology of the network defines the topology of the _Smart Metering_ system and may determine the equipment and the technology to be used. For example, while in the United States a single transformer serves a few end-users, in Europe it can easily reach several hundred. Then, _PLC_ technology is more profitable in Europe than in the United States, where wireless solutions are more desirable. The drivers of the deployments also vary. While in some regions, especially in Europe, _SG_ and _Smart Metering_ projects have been driven by governmental initiatives, funding, or mandates, other regions seek to improve the efficiency of the energy supply system and eliminate electricity theft, as with emerging countries [46; 47]. Additionally, it is worth mentioning the differences in development approaches. For instance, in the U.S. the goal is the security and stability of the electricity network, with a clear objective towards _self-healing_. By contrast, in European countries the trend is towards reduction of greenhouse gases and the promotion of _DG_, _DS_, and _RES_[48]. In addition, the regulation of public band frequencies use in the U.S. is more flexible than in Europe, which has reinforced wireless options in the U.S. Australia, Canada, and Japan have also largely adopted wireless _Smart Metering_ solutions, while China relies on either _PLC_ or _BPL_. In Europe, the strict regulation of public and unlicensed bands initially encouraged early adoption of _PLC_ solutions. Despite recent concerns about _PLC_ reliability, which have prompted European consideration of wireless options, _NB-PLC_ technology is still the most widespread technology for _Smart Metering_ systems in Europe with a wide range of existing pilot projects and massive deployments [41; 46]. The early adoption of _PLC_-enabled _SM_s in Italy, Spain, and China has given this technology its current momentum. Meanwhile, cellular connectivity is witnessing a growing adoption, especially in cases where meter implementations are dispersed. It is also gaining wider acceptance as a feasible, primary connectivity technology, with subscription costs decreasing and utilities becoming more open to using public networks for their _SM_ deployments [49]. There are also differences in the application approach of the _Smart Metering_ systems. Among the European member states, the technical design of _Smart Metering_ systems varies from one country to another. Generally, there is a common understanding of what capabilities a _SM_ should have but often a subset of these capabilities is chosen for their rollout. A recent report from the _CEER_ (_Council of European  
Figure 3: Evolution of _SM_ deployment worldwide (Source: Navigant Research [45]). Reprinted with the permission of Navigant Research, “Smart Electric Meters, Advanced Metering Infrastructure, and Meter Communications: Global Market Analysis and Forecasts” published by Navigant Research, 2014. Energy Regulators_) groups the most common functionalities of the _Smart Metering_ system developed by European countries into five main categories: injected and consumed energy; energy interruptions; exceptional energy consumption; connection to open gateway; and possibility of software update [50]. In general, countries are more likely to have remote upgrade and the measurement of injected and consumed electricity than they are to have interruption alerts, exceptional usage alarms, or an open gateway for access and control of consumption.