How the British energy market handles unmetered energy supplies and how it powers eMobility?

20 OCTOBER 2020 • 7 MIN READ

Paweł Baczyński



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Energy transfer is a continuous process, however, the method of balancing energy consumption is divided into discrete half-hour periods called settlement periods. In the energy market, this settlement is a manner that aligns the difference between energy sold to customers and purchased. So, what is the deal with the balance in energy consumption, how it applies to emobility growth in the UK?

BSCP520 – Unmetered Supplies Registered in SMRS

The energy settlement process would not be overly complicated if all exit points were metered. In practice, this is not always possible, since unmetered supplies are also allowed. This sort of energy consumption needs to be calculated. Unmetered electricity is used e.g. by public street lights, traffic lights, and extra common electric equipment. As a result, unmetered energy estimates for about 1.25% of GB’s total electricity utilization.

To handle these unmetered supplies there is created, in the Supplier Meter Registration Service (SMRS), a dedicated BSCP520 procedure. The common rule indicates that all energy transfer points connected to the Licensed Distribution System should be metered. Exceptions to this rule are called Unmetered Supplies. These Unmetered Supplies are to be approved by the Unmetered Supplies Operator appointed by Licensed Distribution System Operator to act on its behalf.

An Unmetered Supply can be accepted if the electrical load is of a predictable nature (no unexpected spikes etc.) and either less than 500W or it is not practical to install a meter.

Equivalent Meter and Estimated Annual Consumption

As consumption cannot be metered, it needs to be derived. There are two possible scenarios:

  • an Equivalent Meter – It is a hardware/software solution, that provides Half Hourly data
  • an Estimated Annual Consumption – calculated by UMSO (The Unmetered Supplies Operator) to estimate annual consumption per MSID based on circuit watts, percentage of full load used, and the number of devices.

We’ll take a closer look at an Equivalent Meter. The procedure of Half Hourly Trading, Equivalent Meter consists of 3 steps:

  • The Meter Administrator calculates and validates metering data from the Equivalent Meter for each MSID (Metering System Identifier) for each settlement day and sends that to HHDC (Half Hourly Data Collector). The format of the file is defined.
  • HHDC validates this data. In case there is missing or invalid information it sends the details to the Meter Administrator.
  • MA re-sends corrected information if necessary.

There are two types of Equivalent Meters:

  • passive meters, that allocate consumption across the settlement periods based on the relation of annual burning hours and the duration of the day,
  • dynamic meters, that allocate consumption across the settlement periods based on the number of PECUs – Photo-Electric Control Unit – and actual switching times.

Power Data Associates has found that annual energy consumption is typically 1% lower using the switching times provided by the PECU Array compared with a passive calculation. As a result, many customers save thousands of pounds each year.

An Equivalent Meter needs to perform calculations to produce Summary Inventory, necessary documents i.a. for accounting purposes, and settlements with vendors.

How is it actually calculated?

Charge Code specifies the associated circuit watts and other technical information for the Apparatus. Switch Regime specifies the switching times and other technical information for the electric equipment.

For Charge Code & Switch Regime multiply the number of items by the circuit watts for the relevant Charge Code by the seconds attributable to the Switch Regime and divide by 1,000 to determine the kWh.

The second's attributable need to be derived either from

  • actual switching times or,
  • fixed switching times or
  • from the duration of the day (sunset/sunrise times provided by Astronomical Almanac)

This process is repeated for each half hour of the day.

Why unmetered energy supplies matter?

Thanks to unmetered energy supplies, unique applications in public infrastructure and an elaborated billing system Public Charging Points in Great Britain became easy to develop. In 2019 emobility market was estimated to reach ~7-10 million EVs by 2030, which means this segment will require ~28,000 Public Charge Points by 2030.

Current stats show that there are 19,828 accessible public charging points of which 3,568 are rapid chargers. Behind the user-oriented approach, there is a whole network with various participants - private and public - creating accessible and often cost-shared solutions. By regulating settlements between vendors in Great Britain the green growth ultimately contributed to the dynamic development of emobility market. Procedures such as BSCP520 regulate the settlement of unmetered energy consumption accelerating emobility growth. This case was to present detailed, one of the successful ways to unlock greener solutions applied through a public-private sector collaboration.