Half-Hourly Metering Data: What It Is and Why We Need It

What HH data is

Half-hourly metering data is a record of your electricity consumption in 30-minute blocks across the year — 17,520 data points per year per meter. Most UK commercial sites above 100kW peak demand are mandatorily HH-metered; smaller sites can be HH-metered voluntarily. The data shows the exact shape of your consumption: when you draw most power, when you draw least, what your daytime vs evening vs overnight load profile looks like.

Why HH data matters for solar sizing

Rule-of-thumb solar sizing — taking annual kWh and dividing by 870 — gets within 25-40% of the right answer. HH-data sizing gets within 3-5%. The difference matters because:

• Over-sizing creates excess export (paid at SEG rate, 4-15p/kWh) where the kWh would have saved import (worth 25-31p/kWh)
• Under-sizing leaves money on the table — every kWh you could have self-consumed at 28p/kWh that you didn't install
• Battery sizing — without HH data, battery sizing is genuinely guesswork. With HH data, we can calculate the exact battery capacity that lifts self-consumption from baseline to 85%+
• Peak-shaving analysis — commercial DUoS and TNUoS charges are based on peak demand windows. HH data reveals peak periods and lets us size battery for DUoS reduction

How to pull HH data from your supplier

1. Confirm your meter is HH-metered — your bill should say so. Some smart meters report HH data but are not formally "HH-metered" for billing purposes.
2. Request data from your supplier — most large commercial suppliers (EDF, npower Business, Drax, SSE Business, British Gas Lite, Engie) provide HH data on request, typically free to existing customers. Request 12 months as a CSV.
3. Alternative — Meter Operator (MOP) — your MOP holds raw HH data and can provide it. Your bill lists the MOP code.
4. Third-party access — KMM can act on your authority to pull HH data from your MOP. We have a Letter of Authority template that takes 5 minutes to sign.

What HH data looks like

A typical HH data extract is a CSV with columns: MPAN, date, period (1-48 across the day), kWh consumed, optional kWh exported. 365 rows × 48 periods × at least 4 columns = 70,000+ data points. We process this in our modelling tools and overlay against PVGIS-modelled generation for your specific roof orientation.

If you don't have HH data

For smaller commercial sites that aren't HH-metered, we work from annual kWh and sector-typical load profiles. The sizing is less precise but still within 8-15% of optimal for most simple commercial operations (single-shift, daytime-only). For complex operations (multi-shift, refrigeration, anything with significant peaks) we strongly recommend installing a temporary clamp-meter for 4-6 weeks to capture profile data before quoting — costs around £200 and we credit it against the install.

What KMM does with your HH data

1. Cleans and validates the data (typical issues: missing days, time-zone shifts at BST changeover, demand reset markers)
2. Builds an annual profile chart — average weekday vs weekend, summer vs winter, peak vs off-peak
3. Overlays modelled solar generation for your roof — every 30-minute block, every day of the year
4. Calculates true self-consumption ratio for every system size scenario
5. Recommends a system size that maximises ROI given your actual load shape
6. Optionally models 4-6 battery sizes against the residual import shape, showing battery payback for each

FAQs