A practical deep dive into multipurchase contracts for UK businesses

Multipurchase contracts let UK businesses lock in a predictable share of their electricity spend while retaining flexibility to benefit from market movements. For portfolios of 1‑5 GWh a well‑structured deal can shave 5‑10 % off the average spot price, improve cash‑flow certainty and support SECR reporting. The thesis of this article is that, by matching contract periods, tranche sizes and trigger caps to a company’s load profile, the risk‑reward balance can be optimised without the complexity of full‑hedge PPAs.

Understanding Multipurchase Contracts

What they are

Multipurchase contracts, sometimes called “flexible volume” or “partial‑hedge” agreements, are negotiated arrangements where a buyer commits to purchase a predefined volume of electricity at a contracted price, while the remainder of the demand is settled on the spot market. The contracted volume can be delivered over a single period or split across several tranches, each with its own price and risk parameters.

Why they matter for 1‑5 GWh portfolios

A portfolio of 1‑5 GWh represents the typical annual consumption of a mid‑size manufacturing site or a chain of retail outlets. At this scale the cost of a full‑hedge PPA is often prohibitive, yet exposure to volatile spot prices can erode margins. Multipurchase contracts provide a middle ground: they lock in a baseline cost, reduce exposure to price spikes, and still allow the business to capture upside when the market falls.

Key Design Elements

Period choices: monthly, quarterly, seasonal

The contract period determines how often the volume commitment is measured and settled. Common choices are:

• Monthly – aligns with most utility billing cycles and offers the greatest granularity for matching short‑term demand fluctuations.
• Quarterly – reduces administrative overhead while still providing reasonable alignment with seasonal load patterns.
• Seasonal – typically split into winter (October‑March) and summer (April‑September). This is useful for businesses with clearly defined heating or cooling loads. Choosing the right period is a trade‑off between flexibility and predictability. For a 2 GWh portfolio with a strong winter peak, a seasonal split often yields the best risk‑adjusted outcome.

Tranches and volume allocation

Tranches break the total contracted volume into smaller blocks, each with its own price reference. A simple two‑tranche structure might be:

• Core tranche – 40 % of annual volume, fixed for the full contract term.
• Flex tranche – 60 % of volume, priced quarterly and subject to caps and floors. More sophisticated designs can include a third “contingency” tranche that only activates if demand exceeds a predefined threshold.

Caps, floors and trigger mechanisms

Caps and floors protect both parties from extreme price movements. A typical arrangement includes:

• Cap – the maximum price the buyer will pay for the flex tranche. If the market price exceeds the cap, the seller absorbs the excess.
• Floor – the minimum price the seller receives. If the market falls below the floor, the buyer pays the floor price.
• Trigger – a pre‑agreed market price level that, when breached, automatically switches the flex tranche from the spot price to the capped price for the remainder of the period. Industry practice, informed by TUS’s experience across 150 + GWh of flex management, shows that caps set 5‑15 % above the average spot price over the previous 12 months strike a good balance between cost certainty and upside potential.

Fixing non‑commodity components

Electricity contracts contain two cost elements: the commodity price (the kilowatt‑hour price) and the non‑commodity components such as network charges (DUoS, TNUoS), climate levy, and regulatory fees (CCL, REGO). Non‑commodity components are relatively stable and can be fixed at the outset of the contract. Doing so simplifies accounting and aligns with SECR reporting, where the commodity and non‑commodity parts are disclosed separately. For most multipurchase deals, fixing non‑commodity components at the prevailing Ofgem‑published rates locks in the majority of the total cost, leaving only the volatile commodity price to be managed.

Worked Example

Assumptions

• Annual demand: 2 GWh (≈5,480 MWh per month).
• Contract period: Seasonal (Winter vs Summer).
• Tranche split: 30 % core, 70 % flex.
• Core price: £55 /MWh (fixed, includes commodity and non‑commodity components).
• Flex price reference: Quarterly average spot price.
• Cap: 10 % above the quarterly spot average.
• Floor: 5 % below the quarterly spot average.
• Spot price assumptions (based on recent Ofgem data):
  • Winter Q1: £70/MWh, Q2: £65/MWh, Q3: £60/MWh, Q4: £68/MWh.
  • Summer average: £58/MWh.

Calculations

1. Core tranche volume: 30 % × 2 GWh = 0.6 GWh (600 MWh) fixed at £55/MWh → £33,000 annual cost.
2. Flex tranche volume: 1.4 GWh (1,400 MWh) priced quarterly.
   • Q1: Spot £70, cap £77, floor £66.5. Spot is below cap, above floor → price £70. Cost = 350 MWh × £70 = £24,500.
   • Q2: Spot £65, cap £71.5, floor £61.75 → price £65. Cost = 350 MWh × £65 = £22,750.
   • Q3: Spot £60, cap £66, floor £57 → price £60. Cost = 350 MWh × £60 = £21,000.
   • Q4: Spot £68, cap £74.8, floor £64.6 → price £68. Cost = 350 MWh × £68 = £23,800.
3. Total flex cost: £24,500 + £22,750 + £21,000 + £23,800 = £92,050.
4. Annual contract cost: Core £33,000 + Flex £92,050 = £125,050.
5. Spot‑only benchmark: 2 GWh × average spot (£65.5) = £131,000.
6. Saving: (£131,000 − £125,050) ÷ £131,000 ≈ 4.5 %. The example demonstrates a modest but meaningful reduction in total spend, with the added benefit of cost certainty for the core tranche and a capped exposure for the flex tranche.

Outcome and comparison

If the market had spiked to £85/MWh in Q1, the cap would have limited the buyer’s price to £77/MWh, saving £8 /MWh on 350 MWh – a £2,800 reduction. Conversely, if the market fell to £50/MWh, the floor would have prevented the buyer from benefiting fully, but the net effect across the year remains a net saving versus an unhedged position.

Practical Considerations for UK Businesses

Supplier selection – leveraging TUS’s 30+ supplier panel

TUS manages a vetted panel of over 30 electricity suppliers, each offering bespoke multipurchase structures. By tapping this panel, a finance director can obtain competitive caps and floors that have historically beaten supplier projections by 20 % in the last 12 months. The breadth of the panel also enables rapid switching through the free Yolk portal, where the average switching saving is 27 %.

Risk management and reporting under SECR

SECR requires organisations to disclose both the commodity price and the associated network and policy charges. A multipurchase contract that fixes non‑commodity components simplifies this split, allowing the energy team to report a stable “non‑commodity” line item while still demonstrating active commodity risk management through the flex tranche.

Using the Yolk portal for monitoring and optimisation

The Yolk portal provides real‑time visibility of contract utilisation, cap triggers and remaining flex volume. By reviewing the dashboard monthly, operations leaders can adjust internal consumption (e.g., shifting non‑essential loads) to stay within the most favourable tranche, further enhancing the 5‑15 % saving potential cited for voltage optimisation projects.

Bottom line

Multipurchase contracts are a pragmatic tool for UK businesses with 1‑5 GWh of annual demand. By selecting appropriate periods, tranche structures, and cap/floor levels, a company can lock in a baseline cost, limit exposure to price spikes, and still capture market upside. Leveraging TUS’s extensive supplier panel and the Yolk portal reduces administrative burden and improves the likelihood of achieving 5‑10 % total spend savings, while supporting SECR compliance and delivering a clear, defensible procurement strategy.