A practical deep dive into multipurchase contracts for UK businesses

Thesis

Multipurchase contracts are a middle ground between a pure spot‑market exposure and a long‑term fixed‑price deal. For businesses that consume between 1 and 5 GWh a year they provide price certainty, the ability to capture favourable market movements, and a clear framework for managing risk across the contract term.

Why multipurchase matters for mid‑size portfolios

A 2 GWh portfolio translates to roughly 5 GWh of annual electricity use for a typical UK manufacturing site. Under the SECR (Streamlined Energy and Carbon Reporting) regime, any reduction in price volatility directly improves the cost‑per‑tonne‑CO₂ metric that finance directors must report to DESNZ. Moreover, the Capacity Market and TNUoS charges are applied on a per‑MWh basis, so a predictable energy price simplifies cash‑flow forecasting and can improve the company’s credit rating.

How the contract is structured

Period choices

Multipurchase contracts can be sliced into monthly, quarterly or seasonal periods. The choice depends on the load profile:

• Monthly – best for businesses with a relatively flat demand curve; it aligns with most supplier invoicing cycles.
• Quarterly – suits firms that see seasonal peaks (e.g., food processing) and want to smooth out quarterly price swings.
• Seasonal – ideal for highly seasonal users such as horticulture, where winter demand is a fraction of summer demand.

Tranches, caps and triggers

A typical contract is built from tranches – blocks of energy (e.g., 200 MWh) purchased at a pre‑agreed price. Each tranche can have:

• Cap – the maximum price the buyer will pay for that block, protecting against market spikes.
• Floor – the minimum price the supplier receives, ensuring they stay in business.
• Trigger – a market‑price threshold that, when breached, automatically shifts the next tranche to a different pricing formula (e.g., from a fixed price to a market‑linked price). These mechanisms allow the buyer to lock in a baseline cost while still benefiting from favourable market moves.

Timing of non‑commodity components

Non‑commodity elements – network charges, renewable obligation certificates (RO), and the Climate Change Levy (CCL) – are often fixed at contract start. However, fixing them too early can lock in a higher-than‑necessary cost if regulatory rates fall. The best practice is to:

1. Fix commodity price (the MWh price) early, using the tranches and caps.
2. Delay non‑commodity fixation until the regulator publishes the next tariff round (usually Q2 for DUoS and Q3 for TNUoS). This approach has helped our clients beat supplier projections by 20 % over the last 12 months.

Worked example – a 3 GWh annual portfolio

Assume a manufacturing firm with a 3 GWh annual demand (250 MWh per month) wants a 24‑month multipurchase contract. The key assumptions are:

• Spot price (2024 average): £45 /MWh
• Capacity market price: £30 /MWh
• Expected seasonal swing: +15 % in winter, –10 % in summer
• TUS’s supplier panel: 30+ vetted suppliers

Step 1 – Choose the period

The firm selects a quarterly period to match its production cycles (Q1 – low demand, Q2‑Q3 – peak, Q4 – moderate).

Step 2 – Define tranches

Quarter	Energy (MWh)	Fixed price (€/MWh)	Cap	Floor
Q1 2025	750	£48	£55	£42
Q2 2025	900	£46	£53	£40
Q3 2025	900	£44	£51	£38
Q4 2025	750	£47	£54	£41
The fixed price is set 5‑10 % above the current spot to account for forward risk, but the cap limits exposure to extreme spikes.

Step 3 – Set triggers

If the spot price exceeds £60 /MWh in any quarter, the next tranche reverts to a market‑linked price calculated as 80 % of the spot plus a 2 % margin. This protects the buyer from runaway costs while still giving the supplier a reasonable return.

Step 4 – Non‑commodity timing

Network charges (DUoS/TNUoS) are left to be fixed after the 2025 tariff review in Q3, giving the firm a chance to capture any reduction from the DESNZ consultation.

Step 5 – Calculate the expected cost

Using the fixed prices for the first year and assuming the spot stays within the caps, the annual cost is:

• Commodity: (750×£48)+(900×£46)+(900×£44)+(750×£47) = £180,300
• Estimated network & CCL (based on 2025 forecasts): £30,000
• Total: £210,300, or £70.10 /MWh. If the spot price fell to the winter low of £40 /MWh, the trigger would not activate and the firm would still pay the fixed price, delivering a £8‑£10/MWh saving versus a pure spot purchase.

Managing the contract with TUS

TUS monitors the contract against market data in real time through the Yolk portal – a free tool that has delivered an average 27 % switching saving for clients who move between suppliers. Our 150+ GWh under flex‑management portfolio gives us the scale to negotiate favourable caps and floors across the 30+ supplier panel. We also provide quarterly performance reports that align with NESO balancing‑of‑plant data, ensuring the contract remains compliant with SECR reporting obligations.

Bottom line

Multipurchase contracts give UK businesses with 1‑5 GWh portfolios a pragmatic way to lock in price, limit exposure to market spikes and still capture upside when the market softens. By selecting the right period, structuring tranches with sensible caps and triggers, and timing non‑commodity fixes to regulator releases, firms can achieve a predictable energy spend that supports SECR and cash‑flow targets. With TUS’s extensive supplier panel and the Yolk portal, the administrative burden is minimal and the financial upside is demonstrable.