Load Control through Smart Meters

Smart meters offer a number of ways to control and monitor loads in the home. This capability is sometimes called Demand Side Response or DSR. There are three basic methods of load control, the customer themselves acting on a signal, using the meter itself to switch the load or, to use the HAN (Home Area Network) to switch a load remotely.

Why do we need to involve the Smart Meter in this process? The Smart Meter holds the tariff information and therefore is one of the key information sources in understanding when and how the load should be managed. It also records the amount of load reduced or increased under this control mechanism at half-hourly intervals to match the way electricity is priced in the wholesale market.

These load control features are an optional part of the SMETS specification meaning that suppliers do not have to offer them to customers. If offered, it is the customer's choice whether to use these services or not.

Currently, only suppliers can use this functionality with the customer's permission, other parties such as DNOs (Distribution Network Operators) cannot use it. This is because the customer needs to give permission and understand the benefits and costs; only the suppliers are in a position to have this interaction with customers. Therefore, it is likely that any load control for the electricity system will be through services offered by suppliers using their customer base.

Customer advantages

  • Save money.
  • Earn money.
  • Reduce emissions.
  • Control appliances.

Industry advantages

  • Balance supply and demand.
  • Improve security of supply.
  • Reduce expenditure on generation.
  • Help to integrate renewable energy.
  • Reduce expenditure on new distribution networks or the reinforcement of existing networks.

Customer acts on signal

Monthly Report on number of Electricity Meters installed by type
Customer manually decides on load control

This is the simplest, requiring just a message to the customer saying that they should reduce or increase load if they want to. The customer would already have agreed a contract showing the payment or price for the service they are providing. Here a Smart Meter is only needed to record the level of customer participation in changing their load.

Demand Reduction Schemes

A typical Demand Reduction scheme will run through the Winter at teatime as this is when the peak demand occurs. Customers will be asked to reduce demand at certain times via a text or app message. By reducing the peak demand, a number of savings can be made:

  1. Avoid high half hourly electricity prices.
  2. Reduce generation capacity including those generators waiting on standby, thereby reducing the risk of blackouts where there would not have been enough generation capacity.
  3. Reduce transmission peak demand - important because the peak demand determines how big a system you need to build.
  4. Reduce transmission losses.
  5. Reduce distribution losses.

No fee is payable to join these schemes and your supplier will pay you for reducing demand. You have nothing to lose by participating.

You need a Smart Meter to participate in these schemes so that the demand reduction can be measured.

Time of Day tariffs such as Economy 7 are a form of Demand Reduction scheme as they encourage customers to move demand away from peak times, however as these are well known we will not cover these in any detail.

Demand Flexibility Service

The National Grid Electricity System Operator (ESO) has developed the Demand Flexibility Service (DFS) to provide another tool for it to reduce demand. The scheme is open to suppliers who can, in turn, offer a scheme to customers and runs from 1st November 2023 to 31st March 2024. They offer a guaranteed acceptance price of £3/kWh. Suppliers can then pass this on to customers as money, points, or prizes.

Diagram showing the 3 phases of the Demand Flexibility Service operation
How the Demand Flexibility Service works

In effect this gives National Grid a control for item 2. in the above list. In 2022/23 domestic and business load provided National Grid with 350MW of flexible load.

New for Winter 2023/24, within day as well as day ahead test notifications have been introduced, to ask consumer households and businesses to reduce their electricity usage at shorter notice than last winter.

Scheme Statistics

Here are some of the latest statistics for the Demand Flexibility Service during November and December 2023:

  • Two live events occurred in November and December 2023
  • Six test events occurred in November and December 2023
  • 43 suppliers and other service providers have signed up to participate in the Demand Flexibility Service
  • 2.2 million businesses and households have signed up to participate in the Demand Flexibility Service
  • Across the 8 events held in 2023 consumer households and businesses have saved a total of 2,507MWh, enough to power over 7.5million households during these events, roughly 27% of GB households.
  • So far participating providers have earned over £9.3million which they have passed onto households and businesses in the form of pounds, points and prizes.
  • The 2 live events were called by the ESO to balance the electricity network on 29th November and 1st December. Across both events participants delivered an average of 497MWh across each hour and a half session. Enough to power nearly 1.5 million homes across the duration of each event.

Scheme Providers

Suppliers and app providers have designed schemes using a mixture of half hourly prices, transmission charges and the National Grid ESO DFS scheme for incentives. It is expected that domestic customers could save up to £100 and businesses more.

Please note that you need a Smart Meter for these schemes and you can only sign up to scheme at a time. Your latest sign up will cancel earlier ones.

These companies are have schemes in place for Winter 2024:

  • British Gas - British Gas's scheme is called Peak Save and you can join online.
  • EDF - EDF Energy's scheme is called Beat the Peak. Sign up for the scheme is now closed.
  • E.On - E.On have a scheme called Energy Shift. They will email eligible customers about the scheme.
  • Equiwatt - Equiwatt have a scheme called powerDOWN and provide an app to optimise savings. Users are rewarded with points.
  • Flexitricity - Operate Demand side response for industrial and commercial customers.
  • Good Energy - have a scheme called Power Pause. Customers can join the scheme through their website.
  • Hugo - Hugo are participating in the scheme through their Energy App. Their scheme is called Winter Cashback and you can join the scheme easily within the app.
  • Loop - Loop are participating in the scheme through their Energy App. Their scheme is called Turn Down and Save and you can join through their app.
  • Octopus - Octopus's scheme is called Saving Sessions and customers can participate through their app.
  • Ovo - Ovo's scheme called Power Move.
  • So Energy - have a scheme called So Rewarding. They will email eligible customers about the scheme.
  • Uswitch - have a scheme called Utrack Money Back and customers can participate through their app.
  • Utilita - Utilita's scheme is called Power Payback. They notify users to reduce demand with text messages, 24 hours before, 1 hour before and when over.

National Grid have provided a full list of all suppliers participating in the Demand Flexibility Service under "Guidance Documents" on their "Document Archive" tab.

Demand Increase Schemes

A Demand Increase Scheme typically works because wind generation occurs when it's windy (obvious we know!) and if there is not enough demand the generation is wasted. Therefore this scheme offers electricity to customers at that time at a reduced price - customers increase demand to take advantage of this.

No fee is payable to join these schemes and your supplier will offer you electricity at a reduced price or free. You have nothing to lose by participating.

You need a Smart Meter to participate in these schemes so that the demand increase can be measured.

Suppliers Schemes

These suppliers have demand increase schemes:

  • Octopus - Trial.

Auxiliary load control switch

Monthly Report on number of Electricity Meters installed by type
Smart Meter 5th Terminal controls load

Smart meters with 5 terminals have an auxiliary load control switch (ALCS) within the meter itself which can be used to switch a second electrical circuit off and on. The switching pattern can be set via:

  1. A calendar in the meter providing the schedule, or
  2. The supplier sending ad hoc commands as required.
The first option above is very like the Economy 7 meters used to control storage heaters today.

The second option here would allow the supplier to act in case of a system emergency, for example when wind generation is suddenly higher or lower than expected.

In both cases the customer has to agree to the overall process before the supplier can use it.

HAN Connected Auxiliary load control switch

Monthly Report on number of Electricity Meters installed by type
Smart Meter sends HAN signal to control load

Smart meters can also control circuits by sending on and off commands across the HAN thus removing the need for a circuit to be wired back to the meter. This method of control is known as HCALCS. Through this method up to 5 devices can be controlled independently (one of these could be the hardwired ALCS circuit mentioned above).

Electric car charging is a good example of how this could be used.

Smart Vehicle Charging

New smart meter-enabled tariffs can reward consumers that charge their electric vehicles (EVs) during off-peak times, such as at night, by passing through savings from using energy at lower price periods.

When combined with smart chargers consumers can automate this process, not only making it easier to shift charging to cheaper periods but also increasing the responsiveness of their vehicle to real time signals such as excess renewable generation or local grid constraints.

New two-way smart chargers can even enable vehicles to act as mini power stations, supplying energy back to the grid or even directly to consumers' home. Given that cars spend over 90% of their time parked, this opens up significant new capacity that would otherwise be wasted. Electric vehicles can also help optimise onsite generation such as solar by providing a battery bank to use surplus green and free energy that would otherwise be exported to the grid.

What is smart charging?

Smart Charging is when the charging cycle can be altered by external events, and the EV effectively integrates with the whole power system in a grid.

This means that, when permitted by the user, the charging of an EV can be paused, or the rate of charge increased or decreased in response to commands received from energy network operators. A key feature of smart charging is that the user remains in ultimate control, setting the parameters to suit their needs while allowing some level of autonomy in return for lower energy costs.

Ultimately, smart charging will allow the user to specify when they require their vehicle (e.g. by 8:00am) and the system will provide the optimal charging profile to deliver the lowest cost while ensuring the vehicle is ready when needed. At times of low demand, the system may charge immediately in one time block or at other times may charge in a series of time blocks in response to fluctuating demand, local network pressure and availability of renewable power but will always meet the specified needs of the user.

Proportional Load Control

The load control methods above have a serious limitation in that they can only switch a load on or off, ideally it would be useful to control some loads proportionally, for example to reduce to charging rate on an electric vehicle to half power.

This capability is being added to version 5 of the SMETS 2 specification.

The new capability will be called the Auxiliary Proportional Controller (APC) and can be used in two ways:

  • APC functionality that can be used in the same way ALCS.
  • HAN-connected Standalone Auxiliary Proportional Controller (SAPC) functionality that will connect to the HAN via the Communications Hub.

(Page updated: 2024-06-14)

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