Electricity is not one price. It never was.
Most people assume electricity has a single price, set somewhere by someone, and passed on to them. It does not work that way. The cost you see on your bill is the end result of a chain of markets, regulators, infrastructure operators, and commercial decisions that stretches from a wind farm in the North Sea to the socket on your kitchen wall.
Understanding that chain does two things. It explains why your bills are what they are. And it reveals why a tariff like Octopus Agile can cut your costs by up to £440 a year simply by connecting you more directly to the price signals already happening in that chain.
Only 9% of UK households are currently on time-of-use tariffs, according to Nesta's 2025 research. The other 91% are paying averaged-out rates that include all the expensive peak-time electricity they did not use. This guide explains the system those 9% have already understood.
The wholesale market: where prices are born
The starting point for all UK electricity prices is the wholesale market. Most UK electricity is traded on EPEX SPOT (European Power Exchange) and through bilateral contracts between generators and suppliers. Prices are quoted in pounds per megawatt-hour (£/MWh) and traded in half-hourly settlement blocks.
Wholesale prices are set by supply and demand, updated continuously. The range is extraordinary:
- Negative prices occur when surplus renewable generation floods the grid and generators effectively pay to have their electricity taken away. Agile users get paid to consume during these events.
- Normal overnight prices in 2026 typically run £20 - 60/MWh, translating to roughly 2 - 6p/kWh on your Agile bill.
- Peak prices on cold, still winter evenings regularly reach £200 - 400/MWh (20 - 40p/kWh).
- Crisis spikes can go far higher. During the energy crisis of 2022, UK wholesale electricity prices briefly exceeded £4,000/MWh - a level that helped drive the surge in consumer bills across 2022 and 2023.
The wholesale price is the heartbeat of the entire system. Everything else is built on top of it.
From wholesale to retail: the layers between you and the grid
Between the wholesale market and your meter sits a stack of costs that, taken together, often double the wholesale price by the time it reaches your bill.
The physical journey electricity takes is this: a power station or wind farm generates electricity at high voltage, which enters the National Grid transmission network for long-distance transport across the country. Regional Distribution Network Operators (DNOs) then step down the voltage and carry it through local cables to homes and businesses. Each step involves infrastructure built and maintained at significant cost.
A typical UK electricity bill at the July 2026 price cap of 26.11p/kWh breaks down roughly as follows:
| Component | Approximate share | Typical cost per kWh |
|---|---|---|
| Wholesale electricity cost | ~40% | ~10p |
| Network and distribution charges | ~25% | ~6.5p |
| Green levies and policy costs | ~15% | ~4p |
| Supplier operating margin | ~15% | ~4p |
| VAT (5%) | ~5% | ~1.3p |
Most suppliers also charge a standing charge - currently capped at 61p/day - to cover fixed infrastructure costs regardless of how much electricity you use. This is why even households that barely use electricity still receive a meaningful monthly bill.
The half-hourly settlement market (and why it matters)
Since April 2021, the UK has operated what is called half-hourly settlement for all electricity meters. This means that the amount of electricity each household consumes is logged in 30-minute blocks and reconciled against the actual wholesale cost of electricity during each of those 30-minute windows.
Before this change, household consumption was estimated using industry-average profiles, which meant the true cost variation across the day was invisible to ordinary consumers. With half-hourly settlement, the infrastructure now exists to charge people the actual cost of the electricity they use, at the time they use it.
This is the technical foundation that makes Octopus Agile possible. Without half-hourly settlement, a time-varying tariff could not be accurately priced or billed. The 2021 regulatory change unlocked the door; Agile walked through it.
Why your supplier's rate includes more than electricity
When you are on a standard variable tariff and see a unit rate of around 26p/kWh, that single number contains multiples layers of cost bundled together invisibly. Your supplier has already bought electricity in advance - often months ahead - and blended together cheap overnight rates and expensive evening peak rates into one flat number you pay all day.
The green levies embedded in your bill fund schemes including the Renewables Obligation, Contracts for Difference (which pay generators a guaranteed price to build new renewable capacity), and the Energy Company Obligation (which funds insulation and efficiency upgrades for vulnerable households). In 2024, UK electricity generation from renewables reached 50.8%, according to Ember - a figure that would not have been possible without these levies sustaining investment over the past decade.
Network charges cover the physical wires, transformers, and substations maintained by National Grid and the regional DNOs. These charges vary by region, which is partly why Octopus Agile prices differ between, say, South Western England and North Scotland.
Ofgem's role: regulator, not supplier
Ofgem (the Office of Gas and Electricity Markets) is the UK's energy regulator. A common misconception is that Ofgem sets electricity prices. It does not. What Ofgem does is set a price cap - a legal maximum unit rate and standing charge that suppliers are permitted to charge households on default (standard variable) tariffs.
The price cap is reviewed quarterly and is designed to track changes in wholesale costs, network charges, and policy costs. When wholesale prices surge - as they did in 2021 and 2022 - the cap rises. When they fall, the cap falls. The current cap (July 2026) sets a maximum unit rate of 26.11p/kWh and a maximum standing charge of 61p/day.
Importantly, the price cap does not apply to fixed tariffs or time-of-use tariffs. Octopus Agile rates are not directly capped in the same way - they track the wholesale market directly, which means they can go higher than the cap during extreme events (there is a separate 100p/kWh cap on Agile) and significantly lower during cheap periods.
Ofgem also licenses suppliers, sets customer protection rules, and investigates market conduct. It is the safety net of the retail market, not the market itself.
Why prices spike - and why they sometimes go negative
Electricity cannot be stored at grid scale in any meaningful quantity. Every unit generated must be consumed at almost exactly the same moment it is produced, or the grid becomes unstable. This physical constraint makes electricity uniquely sensitive to sudden imbalances between supply and demand.
Prices spike when several conditions coincide:
- Cold weather drives up demand for heating (including heat pumps)
- Low wind reduces cheap renewable output and forces expensive gas power stations to run instead
- Peak demand times (typically 4pm - 7pm on weekday evenings) compress millions of households' activity into a narrow window
- Gas price increases raise the cost of the marginal generation source, which sets the whole market price
During such events, Agile users with AgileAlert notifications can see the spike coming 24 hours in advance and shift their discretionary usage to before or after the peak window.
Prices go negative when conditions reverse: a warm, very windy night with low demand means wind farms are generating more electricity than anyone is consuming. Grid operators need to balance supply by either shutting down wind turbines (wasting clean energy) or paying consumers to use more. Agile passes this through as a negative rate - you run your appliances and money flows into your account. These events happen most often between 1am and 6am on weekend nights in spring and autumn.
How Agile connects you directly to wholesale prices
On a standard tariff, you are insulated from the wholesale market. Your supplier absorbs price swings and charges you an averaged rate year-round. The upside is predictability. The downside is that you pay for peak electricity you may never have used.
Octopus Agile passes the wholesale price directly through to your bill, adding a small retail margin and fixed charges. Rates are published for the following day by 4pm each afternoon and update every 30 minutes. The typical range in 2026 looks like this:
| Time period | Typical Agile rate | vs price cap |
|---|---|---|
| 1am - 6am (overnight) | 2 - 8p/kWh | Up to 10x cheaper |
| Morning (7am - 9am) | 12 - 22p/kWh | Below cap |
| Daytime (10am - 3pm) | 10 - 20p/kWh | Below cap |
| Evening peak (4pm - 7pm) | 25 - 45p/kWh | Above cap |
| Plunge pricing events | Negative (you earn) | Paid to consume |
The peak-to-overnight ratio is typically 8 to 20 times. That spread is the opportunity. A household that can shift 40% of its consumption to off-peak hours - through delay timers on appliances, overnight EV charging, and battery storage - realises average savings of £440 per year compared to a standard variable tariff, according to Octopus Energy's own 2023 analysis.
Understanding how electricity is priced is the first step. AgileAlert shows you the live rates for your region so you can act on that knowledge every single day - without having to monitor the wholesale market yourself.