Practical guide
Half hourly data: the 30 minutes that decide whether a project pays
Before anyone quotes kilowatts, look at the site's half hourly data. It answers more questions about a project than any survey.
5 August 2026 · GRID Asset Finance · 6 min read
Annual consumption tells you almost nothing
A single annual kilowatt hour figure is the least useful number in an energy project. Two sites with identical annual consumption can have completely different projects, because one runs a steady daytime load and the other spikes for four hours on a night shift.
Half hourly data replaces assumption with observation. It is normally available from the electricity supplier for sites with half hourly metering, usually covering the previous twelve months.
What to look for in the data
Start with the shape. Where is the base load, when does the site ramp up, and how long does the peak last. Then look at seasonality, weekends and shutdown periods, because those change the self consumption picture substantially.
- Base load overnight, which sets the minimum a battery must serve
- Daytime profile between roughly 10am and 4pm, which drives solar self consumption
- Maximum demand and how often the site approaches it
- Weekend and holiday behaviour, which often reveals avoidable waste
How it changes the specification
A site with strong daytime demand can often justify a larger solar array, because most of what it generates is used on site at the delivered cost it avoids. A site with an evening peak may be better served by a smaller array with storage, or by tackling the peak first.
The same data usually finds savings that cost nothing. Equipment left running overnight, heating and cooling fighting each other, compressors cycling at the wrong time. Those are worth fixing before sizing anything.
Why GRID starts here
Sizing a system to the available roof area is how businesses end up with an asset that exports cheaply for twenty years. Sizing it to the load profile is how they end up with one that pays.
GRID reviews consumption and demand before discussing funding, because the funding only works if the underlying project does.
Common questions
What is half hourly data?
It is a record of how much electricity a site consumed in each half hour period, produced by half hourly metering. It shows the shape of demand across the day rather than a single total.
How do I get my half hourly data?
Ask the electricity supplier or the data collector for the last twelve months of half hourly data for the site's meter point. It is normally supplied as a spreadsheet at no cost.
Why does half hourly data matter for solar?
Because the value of solar depends on how much of it the site uses rather than exports. Half hourly data shows the daytime demand that determines realistic self consumption, and therefore the realistic return.
More insight
- GRID adds Power Purchase Agreements to its UK energy routes
GRID now helps UK businesses compare a commercial Power Purchase Agreement with solar and energy asset finance before committing to a route.
- Capital allowances on commercial solar: what UK businesses actually claim
How capital allowances work on commercial solar in the UK, why solar sits in the special rate pool, and how the Annual Investment Allowance and the 50% first year allowance affect year one cash.
- Grid connection delays: the line item that breaks UK energy project budgets
Why DNO connection timescales and supply upgrade costs derail UK solar, battery and EV charging projects, and how businesses plan funding around them.