Technical guide · HH data

Half-hourly data acquisition for UK commercial solar — 2026

Half-hourly demand data is the single most important input to right-sizing commercial solar. Without it, sizing decisions rely on rule-of-thumb (annual consumption × 60% rule) that systematically over- or under-sizes industrial sites with continuous loads. This guide covers how to obtain HH data from your UK electricity supplier, alternatives where it isn't available, and what to do with it once you have it.

How to request HH data from your supplier

UK commercial sites with smart or AMR meters automatically have half-hourly data captured. Your supplier holds it and is required to provide it on customer request. Standard request:

  • Email or write to your account manager / customer services team.
  • Reference your MPAN (meter point administration number — printed on bills, format 12-345-678).
  • Request "half-hourly consumption data for the past 24 months" (or relevant period).
  • Ask for CSV format (tab-delimited or comma-delimited).
  • Specify whether you want consumption only or import/export breakdown if you have existing generation.

Suppliers typically respond within 5-10 working days. No charge applies for the request (mandated by Ofgem). If supplier is slow or unhelpful, escalate via Ofgem complaint or DCC (Data Communications Company) direct request.

Alternative routes if HH data unavailable

For sites without smart/AMR meters or with new connections lacking historical data:

  • Install temporary metering — current transformers + data logger for 4-6 weeks at the supply position. £800-2,500 cost. Captures demand pattern with sufficient granularity for sizing.
  • Use industry-standard load profiles — Ofgem and Elexon publish standard demand profiles by business type. Less accurate than site-specific data but acceptable for screening-level sizing.
  • Site visit + activity logging — for very small sites (under 100 kW peak), manual logging of equipment switching and operational hours can support an estimated demand profile.
  • Energy management system data — many commercial sites have BMS or dedicated EMS that captures sub-metered demand. Often higher granularity than supplier HH data.

What HH data tells you

A complete half-hourly demand file (17,520 rows for one year) tells you:

  • Annual consumption pattern — total kWh, monthly variation, seasonal trend.
  • Peak demand — maximum half-hourly demand and timing. Critical for transformer sizing and DNO discussions.
  • Base load — minimum demand (typically 3-4am Sunday). Determines minimum self-consumption capacity from solar.
  • Daily pattern — peak hours, ramp-up/ramp-down timing, weekend variation. Critical for solar sizing.
  • Seasonal pattern — summer vs winter consumption. Sites with summer-shutdown have very different optimal solar size than year-round operations.

For sizing solar, the key metrics derived from HH data are: 365-day average demand, summer-midday average demand (when solar generates most), overnight base load, and peak demand timing relative to solar generation pattern.

Technical FAQs

How recent does the HH data need to be?
Most-recent 12-24 months is ideal. Sites with stable operations: 12 months sufficient. Sites with growth/decline trajectory: 24 months helps identify trend. Sites with major operational change in last year: ignore data prior to the change.
What's the typical CSV format I'll receive?
Standard format: row per half-hour interval, columns including date, settlement period (1-48), kWh consumption, and sometimes import/export breakdown. Some suppliers use date+time format; others use settlement period numbers. Either is workable; just confirm format before processing.
Can my supplier refuse to provide HH data?
No — supplier obligation under Ofgem licence conditions. Suppliers must provide HH data on customer request within 10 working days, no charge. Some suppliers slow-walk by claiming "technical limitations" but Ofgem complaint quickly resolves these.
Do I need a smart meter to get HH data?
For sites with peak demand below 100 kW: typically yes (smart meter or AMR). For sites above 100 kW peak: half-hourly settlement is mandatory regardless of meter type, so HH data is captured automatically. The threshold is the "Profile Class 5-8" demarcation in UK metering rules.
Can I get HH export data once I have a solar installation?
Yes. Once your G99 connection is live and SEG arrangement is in place, supplier captures both import and export at half-hourly granularity. Useful for verifying generation forecasts against actual production and for analysing self-consumption percentage post-installation.

Half-hourly sizing guide

How to use HH data once you have it — modelling self-consumption percentage at different system sizes.

Real HH data example

Yorkshire food production site case study — how HH data changed the sizing recommendation.

Interactive calculator

Enter the self-consumption percentage from your HH analysis directly into the calculator.

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