What is reactive power on a business electricity bill?

Reactive power describes the exchange of energy associated with electric and magnetic fields in an alternating-current system [S1]. It affects the electrical loading your connection carries. UK Power Networks normally requires at least 0.95 power factor, subject to its stated conditions [S2]. A reactive-energy bill line needs checking against your own charging terms. Checked October 2026.

Last checked 19 October 2026

What is reactive power?

Reactive power describes energy moving back and forth through electric or magnetic fields in an alternating-current, or AC, system. It supports equipment operation without representing the useful output measured as active power [S1].

Why it matters for your site: your connection carries the associated electrical loading as well as useful power. That is relevant when assessing headroom for chargers or checking a reactive-energy line on your bill [S3].

Power factor expresses active power as a proportion of apparent power. Kilowatts (kW) measure active power; kilovolt-amperes (kVA) measure apparent power [S3]. Use the kVA, kW and power factor guide for conversions and capacity calculations.

Why do network operators charge for reactive power?

Reactive demand uses network capacity. Ofgem’s discussion paper explains the charging rationale and distinguishes reactive energy from active energy [S3]. It is historical background, not a current price schedule. Request the applicable rate, chargeable units and calculation period before challenging a bill.

UK Power Networks publishes a minimum power factor of 0.95 unless otherwise agreed, with conditions covering import, export and operational requirements [S2]. That is a connection condition, not a universal UK billing threshold. Your distribution network operator (DNO), which manages the local network, should confirm your terms.

What should you check before adding chargers or inverters?

Ask your electrical designer to review measured power factor and the proposed equipment’s operating settings. Include solar and battery inverters, which convert electricity between direct current and AC. Check the connection conditions for both import and export rather than assuming one equipment rating describes the whole site [S2].

Read metering and network charges alongside the business electricity price data. Keep reactive charges separate from the energy inputs in the charging cost tool.

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