Although not an entirely new concept, the smart meter market continues to be a major global growth market based on the device’s ability to greatly improve efficiencies for both utility companies and consumers. Markets and Markets estimates the smart meter market to be worth $12.79 billion (2017), and it is expected to grow at a CAGR rate of 9.34 percent from 2017-2022.
Interestingly, the first smart meter was developed pre-Internet, in the 1970s, and it wasn’t until the mid-nineties after the U.S. National Energy Policy Act, and similar utility deregulation efforts across the globe, that smart metering really took off. Widespread deregulation set-up a market-driven pricing environment for utility companies, creating an immediate demand for utility companies to understand the energy consumption rate of their customers in order to keep their costs down, hence a crucial need for smart meters was born.
Modern day smart meters record and report, via a communications network, the consumption of electricity, gas, water, or heating/cooling. By obtaining this level of consumption detail in real-time, utilities can simultaneously reduce costs while increasing customer satisfaction, making smart meter deployments a valuable investment for any type of utility company. Smart meters also play a key role in helping regions meet aggressive climate goals set-up by state and federal governments in many countries.
The benefits are obvious, but from a designer perspective, the types of metering technologies are vast and require detailed knowledge of the market.
The most common type of smart meters use one-way, transmit only communications and are called Automatic Meter Reading (AMC). These meters started out as walk-by or drive-by meters, but eventually have become fully automated with wireless capability, running on a Wide Area Network (WAN).
Advanced Metering Infrastructure (AMI) meters are two-way communications networks that not only produce a reading, but control the meter and equipment and allow the utility to connect or disconnect customers; monitor and anticipate usage changes, allowing for a smart grid operation; and enable software and security updates.
Traditional metrology equipment was used in the earliest smart meters, but today almost all new smart meter designs use electronic equipment, referred to in the industry as static meters.
Electricity meters are probably what most people think of when they hear the term smart meter, and there are two primary kinds of electricity meters. Current Transformers (CT) were the original meter, though now a wide range of MCU-based meters exist, which don’t have the problems associated with transformer-based meters, such as the tendency to get saturated with heavy currents and the susceptibility to tampering.
One of the more popular types of smart meters deployed extensively in Europe and urban areas are Heat Cost Allocator (HCA) devices. These meters are typically used in multi-tenant residential and commercial buildings, and enable a fair cost allocation of a shared heating system, giving tenants heating bills proportional to their usage of the heating system. This meter is hailed by energy conservationists, as it encourages users to reduce consumption, unlike a flat heating bill that doesn’t reward tenants for reduced energy consumption behavior.
In-Home Displays (IHD) is another desired piece of metering, and IHDs are common in homes part of the GB Smart Energy program in North America. These devices have direct wireless connections to the smart meters in the home, and typically use a Zigbee mesh network to display varying utility cumulative and real-time usage rates.
To no surprise to embedded designers, there are numerous communications technologies to choose from when designing a smart meter.
Typical installations use a sub-GHz Field Area Network (FAN) with a star or mesh topology, though another popular option is using equipment with WAN capabilities built directly into the meter with a M2M connection using 2G, 3G or 4G. The new NarrowBand IoT standard has improved the power and cost performance of this approach, creating numerous unlicensed band Low Power Wide Area Network (LPWAN) technology providers. Another major communications network is the Zigbee-based Home Area Network (HAN), which is already deployed in more than 23 million homes in the U.K. The HAN meters have a built-in Zigbee radio, and come with an IHD.
Though, Wi-Fi, Bluetooth and Z-Wave are nowhere to be found in smart meter deployments, due primarily to power constraints. But Bluetooth Low Energy is a viable option if based on a 2.4 GHz radio using a multi-protocol SoC, such as a Silicon Labs Mighty Gecko.
The Power Play
Power is not an issue for electricity meters since they have their own power supply, but power becomes a pivotal issue for heating, gas, and water meters. Specialized lithium batteries have been created for smart meters in recent years – lasting close to 20 years - but not all markets embrace these batteries. China is a good example, as it requires utility customers to replace their double AA batteries every 12-18 months.
Maximizing battery life is an important part of smart meter designs, making the underlying technology components critical to creating a high-performance smart meter unburdened by power restrictions.
Whatever smart meter electronic design pursued, smart meters will continue to prove their worth as a highly efficient way for utilities to compete and run more efficiently, consumers to save money, and societies at large to reduce their environmental footprint.