Key terms and issues explained

Mae’r dudalen yma ar gael yn Gymraeg.

On this page you will find a range of key terms explained. Please click on a letter below to be taken to a list of terms and on "show" to read the explanation.

Paperless tariff/discount

Where a customer receives all communications electronically.

Parent supplier

A supplier that owns enough stock in another supplier to have control of management and operations of that supplier.

Payment method

A method by which a consumer pays for energy. Payment methods are classified into three main categories: direct debit, standard credit and prepayment.

Personal projection

This is based on your actual consumption and is a projection of your future yearly charge. You could compare the personal projection for your current tariff with a personal projection given to you for an alternative tariff by your current supplier, an alternative supplier or a switching site.


A method of payment where consumers pay for credit to their account. Their meter deducts credit from the account based on the amount of energy used by the consumer and the rates that apply to the consumer’s tariff.

Price comparison metric

A figure that can be used to compare the cost of the tariff you are on against alternative tariffs from your own or other suppliers. Also called the Tariff Comparison Rate (TCR). The TCR is calculated as the estimated yearly bill, divided by the amount of energy used each year by a typical low, medium or high user of electricity. The TCR takes account of any standing charge and the unit rate(s) that make up the tariff. The TCR is not based on your personal consumption and should be used as a guide only.

Price Increase Notification (PIN)

If a supplier increases the price of a tariff or varies any term which could cause disadvantage to the consumer, then under our licence obligations it must notify the consumer at least 30 days in advance of the date on which the price increase (or other variation) takes effect.

Principal terms

The most important terms of a supply contract, including the charges, duration, amount of any termination fees and any terms which may reasonably be considered to significantly affect the evaluation by the consumer of the contract under which they are supplied with energy.

Priority Services Register (PSR)

The Priority Services Register is a free service provided by suppliers and network operators to customers in need. Each energy supplier and network operator maintains its own register. To be added to the Priority Services Register, you simply need to contact your energy supplier.

You can receive the services available if you:

  • are of pensionable age
  • are disabled or chronically sick
  • have a long-term medical condition
  • have a hearing or visual impairment or additional communication needs
  • are in a vulnerable situation.

If you live with a child aged under five, network operators also offer priority services relevant to your needs. You may also be eligible for priority services from your supplier if you live with a child aged under five. Contact them to find out about the services they provide. 

The free services that may be available for priority services customer include:

  • Advance notice of planned power cuts. If you are medically reliant on your supply you can arrange for the company that runs your local network (the network operator) to give you advance notice of planned power cuts (for example, where they plan to carry out engineering work).
  • Priority support in an emergency. This could involve your local network operator providing alternative heating and cooking facilities in the event of supply interruption.
  • Identification scheme. This is to reassure you that callers, for example meter readers, are genuine. Suppliers have to provide additional support to help you identify someone acting on behalf of their company, such as arranging a password or showing an agreed picture card upon visit. 
  • Password protection. Network operators must offer to agree a password with you (or your representative) that can be used by any representative of the company to enable you to identify them.  
  • Nominee scheme. Customers can ask their supplier to send communications (such as account statements or bills) to someone you have nominated (for example a family member or carer) who has agreed to receive them.
  • Arrangements to ensure that it’s safe and practical for you to use your prepayment meter. For example, moving a prepayment meter if you are unable to access it safely to top it up.
  • Meter reading services at appropriate intervals. If no person occupying the premises is able to read the meter and there isn’t anyone else that the customer can nominate to read the meter on your behalf, your supplier may be able to read it for you.
  • Accessible information. Account and bill information in an accessible format, for example in larger print or braille.

See more information on the assistance available through the Priority Services Register for people in need.