A practical deep dive into multipurchase contracts for UK businesses

Thesis

Multipurchase contracts are a strategic tool for UK businesses that consume between 1 and 5 GWh a year, allowing them to secure a predictable electricity cost while retaining flexibility to benefit from market movements. By structuring periods, tranches and trigger mechanisms correctly, and by timing the fixation of non‑commodity components, firms can improve cash‑flow certainty, meet SECR and CCL reporting requirements and often achieve savings that exceed supplier forecasts.

Understanding multipurchase contracts

What they are

A multipurchase contract is a forward‑looking agreement where the buyer commits to purchase a defined volume of electricity over a set horizon, but the price is not a single static figure. Instead, the contract is broken into periods (monthly, quarterly, seasonal) and may contain multiple tranches, each with its own price band, cap or trigger. The non‑commodity components – network charges, capacity market payments, and ancillary services – can be fixed separately, giving the buyer control over the total cost structure.

Why they matter for 1‑5 GWh portfolios

For portfolios of this size the cost of a pure spot purchase is volatile, yet the administrative burden of a bespoke bilateral contract is disproportionate. Multipurchase contracts strike a balance: they provide price certainty for the bulk of consumption while allowing the business to capture upside when wholesale prices fall. Under the SECR (Streamlined Energy and Carbon Reporting) framework, predictable energy costs simplify carbon intensity calculations, and under the CCL (Climate Change Levy) the ability to lock in a lower unit rate can reduce levy exposure.

Structuring the contract

Period choices

Period	Typical use case	Advantages
Monthly	High‑frequency load forecasting, short‑term cash‑flow management	Aligns with most finance reporting cycles
Quarterly	Smoother price averaging, reduced administrative overhead	Less exposure to short‑term price spikes
Seasonal (Winter/Summer)	Aligns with demand‑driven price differentials, useful for businesses with clear seasonal patterns	Captures seasonal price differentials without excessive granularity

Choosing the period depends on the firm’s forecasting capability and the volatility of the underlying wholesale market. A mixed approach – monthly for the peak winter season and quarterly for the rest of the year – is common.

Tranches, caps and triggers

A tranche is a volume block (e.g., 0‑500 MWh) with an associated price band. Caps set a maximum price for a tranche; triggers activate a price adjustment when a market index (e.g., the OFGEM‑published 12‑month forward price) moves beyond a predefined threshold.

• Cap example: 0‑300 MWh capped at £45/MWh. If the market price exceeds £45, the buyer still pays £45 for that tranche.
• Trigger example: 301‑500 MWh priced at the market forward price plus a 2 % margin, but if the forward price falls below £35/MWh the margin is reduced to 0 %.

These mechanisms allow the contract to behave like a floor and a ceiling, protecting against extreme price movements while preserving upside.

Timing the non‑commodity components

Network charges (DUoS, TNUoS), capacity market obligations and REGO (Renewable Energy Guarantees of Origin) fees are largely regulatory and change infrequently. Fixing them at contract inception removes a source of cost drift. However, some components – such as the Capacity Market price – are subject to quarterly auction outcomes. Best practice is to:

1. Lock in static charges (DUoS, TNUoS, REGO) at signing.
2. Use a price‑review clause for dynamic components, aligning the review date with the next auction calendar (e.g., the first Thursday of March for the Capacity Market).
3. Integrate with TUS’s Yolk portal – the free portal provides real‑time visibility of network and policy charges, enabling the buyer to adjust the contract at the next review without renegotiating the entire deal.

Worked example

Assumptions

• Annual consumption: 3 GWh (3,000 MWh)
• Period split: Winter (Nov‑Mar) – 1,800 MWh, Summer (Apr‑Oct) – 1,200 MWh
• Winter split into monthly tranches; Summer into quarterly tranches
• Market forward price (Oct 2026) forecast: £48/MWh (winter), £32/MWh (summer)
• Caps and triggers:
  • Winter months – 0‑400 MWh cap £45/MWh, 401‑800 MWh market price +1 % margin, >800 MWh market price +3 % margin
  • Summer quarters – 0‑300 MWh cap £35/MWh, remainder market price +0.5 % margin
• Fixed non‑commodity components (average): DUoS £5/MWh, TNUoS £4/MWh, REGO £2/MWh, Capacity Market £3/MWh (reviewed annually)

Calculations

Winter – January (400 MWh tranche)

• Cap applies: £45/MWh × 400 MWh = £18,000 Winter – February (400 MWh tranche)
• Market price £48 × 1.01 = £48.48/MWh → £48.48 × 400 MWh = £19,392 Winter – March (400 MWh tranche)
• Market price £48 × 1.03 = £49.44/MWh → £49.44 × 400 MWh = £19,776 Winter – remaining 600 MWh (April‑May)
• Market price £48 × 1.03 = £49.44/MWh → £49.44 × 600 MWh = £29,664 Summer – Q1 (300 MWh cap)
• Cap £35/MWh × 300 MWh = £10,500 Summer – Q2 (300 MWh remainder)
• Market price £32 × 1.005 = £32.16/MWh → £32.16 × 300 MWh = £9,648 Summer – Q3 (300 MWh remainder)
• Same as Q2 = £9,648 Summer – Q4 (300 MWh remainder)
• Same as Q2 = £9,648 Total commodity cost = £18,000 + £19,392 + £19,776 + £29,664 + £10,500 + £9,648 + £9,648 + £9,648 = £126,276 Fixed non‑commodity cost = (5+4+2+3) £/MWh × 3,000 MWh = £14,000 Total annual cost = £140,276 → £46.76/MWh

Outcome

If the business had taken a pure spot purchase at the average winter/summer forward price (£40/MWh) plus the same fixed charges, the cost would be:

• Commodity: £40 × 3,000 MWh = £120,000
• Fixed: £14,000
• Total: £134,000 → £44.67/MWh In this example the multipurchase contract is £6,276 more expensive because of the winter caps. However, the contract provides a price floor that protects the business from a potential winter spike (e.g., a 30 % price surge that occurred in 2022). Over a three‑year horizon, the expected volatility reduction aligns with TUS’s track record of beating supplier projections by 20 % in the last 12 months, delivering a net saving when the market spikes.

Integration with TUS services

TUS manages over 150 GWh under flex management, meaning we have the data and optimisation expertise to fine‑tune tranche sizes and trigger thresholds. Our 30‑plus supplier panel gives access to competitive pricing, and the Yolk portal offers a free, real‑time view of network charges, enabling the finance director to monitor the fixed component against actual invoices. By leveraging TUS’s voltage optimisation service (5‑15 % saving with a 2‑3 year payback) the overall electricity spend can be reduced further, complementing the multipurchase strategy.

Bottom line

Multipurchase contracts give UK firms with 1‑5 GWh portfolios a pragmatic blend of price certainty and market upside. By selecting appropriate periods, designing tranches with caps and triggers, and fixing non‑commodity components at the right time, businesses can manage risk, meet SECR and CCL obligations and often outperform supplier forecasts. Partnering with a specialist like TUS adds data‑driven optimisation and a transparent portal, turning a complex contract into a manageable, cost‑effective solution.