Key answer
Maximum demand is measured use; import capacity is the agreed limit
Maximum demand describes the site's highest power demand during the relevant measurement period. Maximum Import Capacity, also called Agreed or Authorised Supply Capacity, is the capacity agreed with the distribution network operator. A bill can charge for reserved kVA even when the site uses less, and excess charges may apply when demand exceeds the agreement.
Do not confuse kW, kVA and kWh
Kilowatt-hours measure energy consumed over time and support the familiar unit charge. Kilowatts measure active power at a point or over an interval. Kilovolt-amperes measure apparent power and can be higher than kW when the site's power factor is below one.
Capacity is commonly agreed and charged in kVA, while interval consumption data is often shown in kWh. Reactive energy or poor power factor can also appear as a separate consideration. Ask an electrical engineer or the relevant network party to interpret site-specific technical values.
- kWh: energy used and billed through unit rates.
- kW: active power demand.
- kVA: apparent power used for many capacity agreements.
- Power factor: the relationship between active and apparent power.
- MIC, ASC or authorised capacity: the site's agreed import limit.
Find the agreed and measured figures
Check the electricity bill, supply contract and connection agreement for capacity, availability, maximum-demand, excess-capacity and reactive-energy lines. Confirm the MPAN, unit, billing period and whether the supplier bundles the charge or passes through the network amount.
Request enough half-hourly data to capture seasonal and operational peaks. A monthly maximum alone does not explain which equipment created it. Map the peak intervals to production schedules, heating, refrigeration, compressors, EV charging and simultaneous equipment starts.
Review unused or exceeded capacity cautiously
Consistently low demand may indicate capacity that is no longer required, while repeated excesses may indicate an undersized agreement or unmanaged peaks. Neither conclusion should be drawn from one quiet month or one exceptional interval. Review expected expansion, electrification, resilience and seasonal loads.
Changing agreed capacity normally involves the distribution network operator and can have engineering, connection and cost consequences. Capacity released today may not be simple or cheap to restore later. Obtain the DNO process, technical advice and written cost implications before requesting a reduction or increase.
Reduce peaks without shifting the problem
Potential measures include sequencing large loads, correcting control settings, repairing equipment, using managed EV charging and investigating power-factor correction. Storage or on-site generation may alter import patterns but requires a wider technical and financial assessment.
Verify the result in interval data and watch for a new peak at another time. Reducing kWh does not always reduce kVA demand, while flattening a brief peak may not materially change annual consumption. Treat energy, demand and agreed capacity as related but distinct metrics.
Sources
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Next step
Start with the bill and interval data
Identify the capacity line, supply number and relevant readings before asking for a change.