What is a Smart Meter?
What exactly is a smart meter and why is it cleverer than the little box currently stuck on the wall? This part looks at what makes a meter smart and how it differs from its conventional predecessors.
Smarter than Your Average Meter …
So what makes a meter smart? Traditionally, meters sit under your stairs or in the garage and are only disturbed when the meter reader comes to take a reading. Well, at first sight, smart meters don’t look a whole lot different as you can see in figure below. Like their conventional cousins, they still sit in infrequently visited locations, but now they’re not even disturbed by meter readers.
Surprisingly, there’s no absolute definition of what a smart meter is and this lack of a standard is one of the obstacles to a wide-scale UK smart metering rollout.
However, this section delves into the widely-accepted characteristics of a smart meter.
In addition to being remotely read, smart meters can be remotely instructed and re-configured. Actions which, in the case of conventional meters, necessitate lengthy site visits and meter changes, can now be per-formed remotely in near-real time.
Actions that can be remotely performed with a smart meter include:
On-demand meter readings. Reading a meter in near-real time in response to a customer phoning the call center, for example.
Change of tariff. Changing tariff rates and tariff structures in response to a supplier-instigated price change or a customer electing to move to a new, innovative smart tariff, for example.
Change of payment method. Switching between credit and pre-payment modes.
Change in read frequency. Changing the consumption read interval from, say, monthly to daily, or even half-hourly.
Load limiting/shedding. Remotely controlling an agreed portion of a customer’s consumption in order to help balance generation and demand or as a means for preventing customers from running up massive debts while still having access to energy.
Tamper alerts. Automatically detecting, notifying, and responding to attempts to tamper with the meter.
Disablement/enablement. Turning supply on and off in response to, say, a tamper alert.
Messaging. Communicating directly with the customer via the smart meter and Home Display Unit (HDU).
Firmware updates. Remotely updating the soft-ware embedded within the smart meter in order to fix bugs or add new functionality.
Smart meters are capable of recording consumption in far more detail than their less sophisticated, conventional cousins. Meter readers typically visit every quarter but not always when you’re at home! So the level of consumption information available to customers and suppliers is pitiful. Suppliers have no means for encouraging people to change consumption behavior and customers have no means of knowing what their consumption behavior is!
Smart meters can record very detailed Time of Use (ToU) consumption down to half hourly and beyond. ToU refers to a meter’s ability to record when consumption takes place rather than just how much is consumed. Customers can see how their consumption varies during the day and respond to new ToU-based lifestyle tariffs that encourage them to use cheaper energy. Changes in behavior can have the effect of flattening consumption peaks which, in turn, reduce the need for expensive, carbon-polluting peaking plant and network reinforcement.
Not just electricity
Smart meters exist for commodities such as gas and water as well as electricity. Given that electricity doesn’t mix well with either gas or water, gas and water smart meters tend to be battery-powered. Battery technology is constantly improving but, to avoid the costs of site visits to replace batteries, these meters tend to spend a lot of the time asleep, waking up according to a schedule to take and transmit readings.
Time to find out about Time of Use (ToU)
A meter that can record ToU is called a ‘restricted’ meter and records consumption by having different registers active at different times. For example, a restricted two-rate meter may have one register that records consumption overnight and another that does so during the day. This enables the supplier to apply different tariff rates that reflect the differential between the wholesale cost of day-time and night-time electricity.
Smart electricity meters, on the other hand, have ready access to a power supply and are therefore frequently used as the means of communicating data from gas and water smart meters. The gas and water smart meters ‘piggy-back’, by communicating via low-power radio to the electricity smart meter, which stores and forwards the data as additional registers within its own meter.
Export as well as import
Whereas conventional domestic meters only record consumption, most smart meters are also capable of recording electricity generated from domestic micro-generation plants and exported to the distribution grid (solar panels, for example). The ability to measure the output from microgeneration means that customers can be fairly rewarded for their contributions, which makes smart meters one of the key enablers for the widespread adoption of microgeneration.
Not quite smart enough …
The following technologies often arise in smart meter conversation but shouldn’t be confused with the real thing.
Automatic Meter Reading (AMR). An AMR meter can be read remotely but reading the meter is the only remote function supported. The benefits of AMR metering are restricted to reducing meter reading costs to the supplier and the ability to bill the customer based on actual meter readings.
Clip-on electricity monitors. These little devices are sensors that clip onto the cables feeding conventional electricity meters and wirelessly transmit near-real time consumption information to a portable display unit located elsewhere in the house. The display unit shows how much electricity is being consumed and how much CO2 this represents.
However, clip-on electricity monitors have significant limitations when compared to smart meters. There’s no equivalent clip-on monitor for gas or water meters, no remote supplier access (so none of the supplier or distributor benefits of smart metering can be realized), and no improvement in billing because the supplier still has to manually read the meter.
Image Credit: tmvissers
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