Half-hourly electricity data

Who has half-hourly metering

Larger sites have been settled half-hourly for many years. Since April 2017, medium-sized sites that used to be in profile classes 05 to 08 have also had to move to half-hourly settlement. The industry's market-wide half-hourly settlement programme is now extending this to all meters, including smaller business supplies with smart meters.

Why it changes pricing

With HH data, suppliers can see exactly when you use electricity, not just how much. Electricity and network costs vary through the day, so a site that uses most of its power in the early evening on winter weekdays costs more to supply than one with the same total use spread overnight.

Capacity (kVA)

Many HH supplies have an agreed supply capacity, measured in kVA, with a daily charge based on it. If your agreed capacity is much higher than you ever use, you may be paying for headroom you don't need. If you regularly exceed it, you may face excess capacity charges. HH data shows your actual peak demand.

Reactive power

Some sites with large motors or older equipment draw reactive power, which shows up as a poor power factor. Many HH contracts include reactive power charges. Power factor correction equipment can reduce them, but get engineering advice before investing.

Time-of-use network charges

Distribution charges often vary by time band, with the most expensive band usually covering weekday late afternoons and early evenings. The exact times vary by region. Moving flexible loads out of the peak band can reduce costs.

Getting your data

Your supplier or meter data provider can usually supply 12 months of HH data, often as a spreadsheet. It is the single most useful thing to share for a larger-site review.

What to look for

• Peak demand compared with agreed capacity
• Overnight and weekend baseload, which shows what runs when you're closed
• How much use falls in the peak network time band
• Changes after new equipment or shift patterns

Reading an HH data file

A typical file has one row per day and 48 columns, one for each half-hour, with kWh values. Plotting a few typical days quickly shows your daily shape: when the site starts up, its peaks, and what is left running overnight.

Baseload: the quiet cost

Baseload is the electricity your site uses when it is closed, such as compressors left on, lighting, IT and refrigeration. HH data makes it visible. A high overnight or weekend baseload is often the easiest cost to reduce, though deciding what can be switched off is an operational decision for you.

Using HH data in a contract review

• Suppliers price your actual profile, so share 12 months of data
• Check agreed capacity against real peak demand
• Look at how much use falls in the most expensive time band
• Flag any planned changes to equipment or shifts

Common mistakes

• Keeping an agreed capacity far above actual need
• Ignoring reactive power charges on the bill
• Sharing only one month of data, which misses seasonal changes

Sources

• Elexon: Market-wide Half Hourly Settlement (elexon.co.uk)
• Ofgem: Energy advice for businesses (ofgem.gov.uk)

Questions

We introduce enquiries to an energy broker partner and may receive a fee. We're not a supplier and don't give whole-of-market advice. How we're paid