Agreed electricity capacity should suit the site's assessed requirements, operating pattern and future plans. Review it when the business changes and when representative demand information becomes available, rather than assuming the answer is always a reduction. This guide helps businesses in Great Britain prepare an initial capacity discussion or a later review with the appropriate technical and commercial parties.
What are agreed supply capacity and kVA charges?
Your connection agreement may describe agreed supply capacity or maximum import capacity (MIC), usually expressed in kilovolt-amperes (kVA). UK Power Networks describes MIC as the maximum power a property can draw from its network. It is different from the kilowatt-hours (kWh) used over a billing period.
Where your tariff includes an availability or capacity charge, check the quantity and rate applied. EDF's small-business terms, for example, define an availability charge linked to available capacity and also address excess-capacity charges. The definitions and calculation applicable to your supply must come from your own agreement and tariff.
Do not assume that every business supply has a separately itemised capacity charge, or that another site's rate applies to yours.
Have the requirement assessed and build a supply record
For a new supply, ask a suitably qualified electrical professional to assess the equipment, operating pattern and planned expansion before a capacity is chosen. Include machinery, electric heating, refrigeration and charging where relevant. Keep the assessed requirement with the connection proposal; BBA can help coordinate the related supplier and metering questions, while technical assessment remains with the relevant professional.
For an existing supply, gather the agreement and representative demand information before deciding whether a change is justified. Start with:
- The electricity meter point administration number (MPAN) and site address.
- The current connection agreement and recorded capacity.
- Recent bills showing the charged capacity, units and rate.
- Available maximum-demand or half-hourly data covering a representative period.
- Equipment removed, added or planned, including charging and electric heating.
- Any previous capacity-change correspondence and effective dates.
Ask a suitably qualified electrical professional to assess the technical requirement. Include seasonal peaks, machinery starting requirements and equipment that may operate together. One quiet month is a weak basis for a permanent change. Equally, an opening-day requirement may not represent a completed building or a business adding equipment. Ask what data period and allowances are appropriate to the site.
If the demand report is in kilowatts (kW) and the agreement is in kVA, ask the professional to reconcile them. Do not treat unlike units as interchangeable or select a new figure from average consumption alone.
Estimate the possible effect on charges
Hypothetical illustration: assume a separately billed capacity rate of 4p per kVA per day, a reduction from 150 kVA to 100 kVA, and an unchanged rate for a 365-day comparison year.
The difference in that charge would be:
50 kVA × £0.04 × 365 = £730 per year.
This is an invented calculation, not a quotation, recommendation or guaranteed saving. It excludes VAT, any alteration costs, excess charges and other changes to the tariff or metering arrangement. An acceptable capacity assessment and the relevant agreements would still be needed.
Before proceeding, ask the supplier which bill items would actually change. A reduced capacity figure does not establish that every fixed or network-related charge will fall by the same proportion.
Confirm the process for an increase or reduction
The distribution network operator (DNO) handles the connection agreement; the supplier handles the energy account and billing. EDF's capacity-change guide identifies the MPAN, address, current capacity and proposed capacity as information to provide to the DNO.
In UK Power Networks' area, its published process involves agreeing a new MIC and completing a revised connection agreement. Its guidance also warns of a delay before the change appears on supplier bills and says reductions cannot be backdated. Other operators' arrangements should be checked directly.
If an increase is needed, ask the relevant network operator to assess availability, required work and any quotation or connection-agreement changes. Do not assume extra capacity can be obtained immediately. For either direction, ask about the permitted frequency of changes, effective date, charges and any metering implications. Keep the completed agreement and supplier acknowledgement, then check the first affected invoice. BBA Energy's bill-validation and meter-coordination services can help organise the commercial follow-through.
Keep enough capacity for the business you are planning
Review the proposed figure against future requirements before approving a reduction. Reinstating surrendered capacity should be discussed with the network, including whether a later increase would require an application, cost or additional work.
A vacant production area today may be needed for a new tenant or machine next year. Record the assumptions behind the decision and who has approved them. Where demand is likely to grow, see our guide to planning an electricity supply.
Use half-hourly consumption information to help understand the operating pattern, while keeping energy use and connection capacity distinct. If the billed capacity disagrees with the existing agreement, investigate that discrepancy first. Correcting an inaccurate bill and voluntarily reducing an agreed capacity are different requests.