Intelligent electricity meters – smart meters

Over the next few years, conventional analogue electricity meters will be replaced by so-called smart meters. Since January 2010, intelligent meters have already been mandatory in certain cases. With major customers, such systems have already been used for a longer time.

A more consistent capacity utilisation of the electricity grids and consumption control

Intelligent metering systems (smart metering systems) are intended to allow a more consistent capacity utilisation of the electricity grids and consumption control according to the availability of renewable energy (for example from the wind and the sun). As a result, power stations can be operated more uniformly, more efficiently and in a more environmentally friendly way. In addition, the systems allow remote readout and facilitate or eliminate on-site meter reading.

By means of smart meters, households obtain more information about their own energy consumption and about the possibility to reduce energy costs by preferential use of consumption periods during which low tariffs are valid. Intelligent metering systems can also record the consumption of district heating, natural gas or water.

Smart meter: electronic meter and data transmission system

Intelligent metering systems consist of a smart meter which records consumption precisely to the second and a system (smart meter gateway) for the transmission of data to the data centre of the relevant utility company. The customers can either read their consumption data directly off the smart meter or the gateway or they can retrieve the data via the Internet from the data centre of the utility company. Current as well as past energy consumption values can be displayed on a daily, monthly and yearly basis. In order to ensure data protection and data security, all devices used have to meet the relevant statutory requirements.

Data transmission within the household or the company

Within a residential or a commercial building the smart meters can be connected to the gateway or other smart meters via cable, power line or wireless communication technologies. Devices which communicate wirelessly can use different frequency bands and wireless standards. For example, it is possible to use the frequency bands in the range from a few tens or hundreds of megahertz for short-range radio applications released by the German Federal Network Agency (BNA). In these frequency bands maximum transmitter powers between 10 and 500 milliwatts are allowed. There is no complete overview of the devices used in Germany.

Data transmission to the data centre of the utility company

Various transmission media are also available for transmitting data from the gateway to the data centre of the utility company. These include wired telephone networks, mobile telephone networks as well as the electricity grid.

Devices transmitting data via mobile communications use a transmission module capable of transmitting within one of the existing mobile radio bands. The transmitter powers of the modules are equal to those of mobile phones in the relevant frequency bands (for example a maximum of 2 watts in the 900 MHz band or 1 watt in the 1,800 MHz band).

Low exposure due to wirelessly communicating smart meters

Individuals in the vicinity of wirelessly communicating smart meters are exposed to the electromagnetic fields of the devices and absorb part of the emitted radiated power. However, it can be assumed that the resulting exposures due to electromagnetic fields remain low: whereas their transmitter powers are similar, in contrast to using personal communication devices such as mobile or smart phones, there is usually a large distance between the transmitter and individuals during the operation of wireless smart meters.

The field strengths drop off rapidly with distance from the transmitter. Neither meters nor gateways are usually installed in rooms intended for the extended presence of individuals. Moreover, smart meters do not communicate among themselves or with the gateway continuously, but during intervals with long breaks in between. To that end, radio connections are briefly established and are then terminated. The same applies to the connection to the data centre of the utility company in case a mobile telephone network is used.

It can therefore be assumed that typical exposures are far below the limits recommended to protect human health. The first measurement results published confirm this estimation. Under these circumstances, direct health effects as well as interference with active medical implants such as pace makers can be excluded according to current scientific knowledge.

In order to comply with the principle of radiation protection, that is, to avoid or minimise exposure if possible, preference can be given to smart meters using wired data transmission.