Wholesale Energy Pricing (UK): Futures, Day-Ahead & Agile

Introduction: How UK Energy Suppliers Buy Electricity

Wholesale Energy Pricing plays a central role in UK electricity costs. Suppliers don’t just buy electricity on the spot — most of it is purchased in advance through the futures market, a process known as hedging. By locking in contracts months, or even a year, ahead, suppliers can manage price volatility, secure supply, and keep costs more predictable for households and businesses.

Once wholesale prices are set, suppliers then add on other elements such as distribution charges, operating costs, and policy levies (like carbon taxes or renewable investment schemes). These costs are all bundled together into the tariffs customers see on their bills. That’s why changes in wholesale energy pricing ripple through into everyday UK electricity prices.

If you want a deeper dive into hedging, Simply Switch has a clear guide here: Business Energy Hedging.

Reading Guide

This article is about Wholesale Pricing is a comprehensive read, drawing on both data and hands-on Agile testing.

Use the Table of Contents below to jump straight to the questions that matter most — or scroll through at your own pace.

Day-Ahead Electricity Pricing in the UK

While most electricity is bought months in advance through hedging, suppliers sometimes need extra power closer to real time.

This is where the day-ahead market comes in. Suppliers bid in half-hourly auctions to buy electricity for delivery the next day. Prices are set using marginal pricing, which means the most expensive generator needed to meet demand — often a gas plant — sets the final wholesale price for everyone. Even when cheaper renewables like wind or solar are available, gas can still drive the cost.

Occasionally, there’s so much supply on the system that the market tips into negative pricing, where generators effectively pay to offload power. These spikes and dips show just how dynamic the wholesale market can be — and why tariffs linked to it, such as Agile, change every 30 minutes.

I have long been interested in the relationship between the Octopus Agile tariff, the underlying wholesale cost, and day-ahead auction pricing.

To understand it better, I contacted a couple of day ahead auction data providers to see how much it would cost to access detailed wholesale pricing information.

Bearing in mind that this energy-stats website is just a geeky hobby for me, the subscription fees were way out of reach.

You can see single-day UK auction prices here: Nord Pool UK day-ahead prices

Access to historical or more expansive datasets requires a subscription. For example, the Nord Pool Data Portal charges €1,200 per year for up to three users on the BASIC plan.

This challenge led me to explore the process of reverse engineering indicative wholesale electricity prices from the Agile data that is publicly available.

Here’s a graph I came up with showing Indicative Daily Average UK Wholesale Electricity Pricing for the last 2 years:

Indicative Daily Average UK Wholesale Electricity Pricing (last 2 years)

How the Octopus Agile Tariff Reflects Day-Ahead Pricing

The Octopus Agile tariff is a real-world example of a time-of-use tariff that passes through wholesale costs almost directly. Every 30 minutes, the price you pay is linked to the day-ahead wholesale market, with a small adjustment for distribution charges and balancing costs.

This setup means household bills track market movements in near real time. When wholesale prices fall — such as during windy nights or sunny afternoons with strong renewable output — Agile users often benefit. But if prices spike due to gas setting the marginal price, customers see that reflected too.

For anyone interested in tracking Agile pricing, we provide current and historical data on our dedicated page: Octopus Agile Tariff Pricing.

You can see in this graph from Tuesday 24th June 2025, how 30 minute pricing can fluctuate throughout a single day.

Graphs like these, from Agile and other tariffs, are shared daily on Energy-Stats UK’s social media (Twitter/X, Bluesky, Mastodon), so it’s worth following us to stay up to date.

How the Agile Tariff is Calculated from Wholesale Pricing

The Agile formula has been transparent since launch in 2018. In practice it works like this:

1. Start with the wholesale auction price (e.g. £123/MWh = 12.3p/kWh).

2. Apply the Agile multiplier (×2.2).

3. Add the peak-time charge between 4–7pm.

4. Include VAT (5%).

So a £123/MWh slot at 10am becomes ~28.4p/kWh, while at 5pm it rises to ~40.4p/kWh.

Energy analysts often compare these costs against benchmarks like spark spreads (the profitability of gas plants) to see how wholesale conditions flow through to tariffs. For households, the key takeaway is that Agile makes these wholesale dynamics visible on your bill.

Important: Wholesale pricing data from Nord Pool (or Epex) is often in UTC, so during daylight saving periods it may be an hour out from UK local time (BST).

Guy Lipman has even more information on the formula showing us the slight differences used between each of the 14 DNO regions: Guy Lipman Agile Formulas

Reverse Engineering Indicative Wholesale Electricity Prices from Agile

To end up with the wholesale cost I had to look at doing the Agile calculation in reverse.

Because we need both Octopus Agile and Octopus Outgoing Agile pricing to account for price caps, I could only go back to May 2019 (when outgoing started).

So I was able to replay my script against all historical Agile data and come up with indicative wholesale electricity pricing for each 30-minute slot.

In this next graph you can see the last 7 days of Indicative Wholesale Price, Agile Import and Agile Outgoing tariffs.

Indicative Wholesale Electric, Agile Import and Agile Outgoing (last 7 days)

Indicative Average Wholesale Electricity Pricing for each 30 minute time slot (last 30 days)

Indicative Wholesale Electric Daily Average and Gas / Electric Tracker (last 2 years)

Graphs, Dashboards and CSV Data

I’ve run the formulas against all pricing data going back to the start of Agile Outgoing in May 2019. A daily script keeps everything up to date using Octopus’ published data, so the indicative wholesale prices and graphs refresh every day.

On this page you’ll see fixed timeframe graphs for quick reference. If you want more flexibility, the user-configurable dashboard lets you explore a wider range of time periods and compare different tariffs.

For deeper analysis, you can also download the indicative wholesale electricity data in CSV format from the Download Historical Pricing Data page. These files update daily, so you can run your own analytics or track historical wholesale prices over time.

Note: Please give credit and link back to Energy-Stats UK if you use the data publicly. Thank you.

Disclaimer

These figures are provided on a best-endeavours basis and should always be treated as indicative wholesale pricing rather than exact market data.

The values are reverse-engineered from day-ahead market prices and Octopus Agile tariff formulas, so while they give a realistic picture of historical wholesale electricity costs, they are not an official dataset.

Other Smart Tariffs

Explore more time-of-use tariffs in our Time-of-Use Tariffs hub. Quick overview:

• Agile — half-hour day-ahead pricing that tracks wholesale costs.

• Cosy — time-bands for cheaper heating periods.

• Go — overnight EV charging at low rates.

• Flux — export-friendly for home solar/battery users.

• Intelligent Go — smart-scheduled EV charging at cheap times.

• Tracker — daily variable unit rate linked to wholesale benchmarks.

Tip: these tariffs reward shifting usage to off-peak times — good for bills and for a more renewables-friendly grid.

Looking for a full breakdown of these tariffs? Check out our Time-of-Use Tariffs hub, where we compare Agile, Cosy, Go, Flux, Intelligent Go, and Tracker side by side and explain how each one works.

If you switch to Octopus Energy using my referral link, you can claim £50 FREE credit. Thank you if you do!