A practical deep dive into multipurchase contracts

Core thesis

Multipurchase contracts provide a middle ground between full spot exposure and a fixed‑price supply agreement, allowing organisations that consume 1‑5 GWh a year to manage price risk without sacrificing the ability to benefit from market dips. By structuring purchases in defined periods, tranches and caps, a finance director can align energy spend with cash‑flow planning and regulatory obligations such as the SECR reporting requirements.

How a multipurchase contract is built

A multipurchase arrangement is a negotiated agreement with a supplier or a panel of suppliers – TUS works with a 30+ supplier panel – that defines a series of purchase windows and the pricing methodology for each window. The contract typically covers the non‑commodity components (capacity, network charges, REGO) up‑front, while the commodity price is linked to a reference index such as the N2EX or the UK Power Exchange (UKPX) spot price.

Period choices – monthly, quarterly, seasonal

• Monthly – best for organisations with volatile demand patterns or tight cash‑flow cycles. Prices are set for each calendar month, allowing the business to match procurement to actual consumption.
• Quarterly – a common compromise; it reduces administrative overhead while still providing regular price updates. Quarterly windows align well with most budgeting cycles.
• Seasonal – typically winter (Oct‑Mar) and summer (Apr‑Sep). This is useful when demand is strongly weather‑driven, for example a manufacturing plant with heating loads.

The choice of period influences the granularity of caps and triggers. Shorter periods give tighter control but may increase transaction costs.

Tranches, caps and triggers

A tranche is a defined volume of energy that the buyer commits to purchase at a predetermined price band. Multiple tranches can be layered to create a stepped risk profile.

Tranche	Volume (MWh)	Price band (p/kWh)	Cap	Trigger
1	500	5‑7	Upper cap 8	Spot price > 8 triggers purchase at cap price
2	800	6‑8	Upper cap 9	Spot price > 9 triggers purchase at cap price
3	1,200	7‑9	Upper cap 10	Spot price > 10 triggers purchase at cap price

• Cap – the maximum price the buyer will pay for the tranche. If the market price exceeds the cap, the contract price applies.
• Trigger – the market price level that activates the tranche. Below the trigger, the buyer purchases at the spot price; above it, the tranche price is used.

Caps protect against price spikes, while triggers ensure the buyer does not over‑pay when the market is low.

Fixing non‑commodity components

Non‑commodity elements – transmission and distribution use of system (TNUoS, DUoS), capacity, REGO and ancillary services – can be fixed at contract start. TUS typically locks these components for the full contract term, delivering a predictable baseline cost. Fixing early is advisable when:

• The business is subject to the SECR energy‑use reporting, requiring a stable baseline for carbon accounting.
• The organisation has a long‑term capital investment plan and needs certainty for project finance models.
• Market forecasts indicate rising network charges, as seen in the recent Ofgem consultation on TNUoS reforms.

Worked example – 2 GWh annual portfolio

Assumptions (Oct 2024 – Sep 2025)

• Annual consumption: 2 GWh (2,000 MWh)
• Period choice: quarterly
• Spot price forecast (average p/kWh): Q1 = 6.5, Q2 = 7.2, Q3 = 5.8, Q4 = 9.0
• Non‑commodity fixed cost: £30 MWh (covers TNUoS, DUoS, REGO)
• Tranche structure:
  • Tranche A – 600 MWh, cap £8.0, trigger £7.5
  • Tranche B – 800 MWh, cap £9.0, trigger £8.5
  • Tranche C – 600 MWh, cap £10.5, trigger £9.5

Quarter‑by‑quarter calculation

Q1 (Oct‑Dec) – Spot 6.5 p/kWh, below Tranche A trigger. Purchase 600 MWh at spot (6.5 p) = £39,000. Remaining 400 MWh taken from Tranche B at spot (6.5 p) = £26,000. Q2 (Jan‑Mar) – Spot 7.2 p/kWh, still below Tranche A trigger. Same allocation as Q1, total £65,000. Q3 (Apr‑Jun) – Spot 5.8 p/kWh, well below all triggers. All 2,000 MWh purchased at spot = £116,000. Q4 (Jul‑Sep) – Spot 9.0 p/kWh, above Tranche B trigger (8.5) but below Tranche C trigger (9.5). Allocate 800 MWh to Tranche B at cap £9.0 = £72,000. Remaining 1,200 MWh taken from Tranche C at spot 9.0 = £108,000.

Total commodity cost

£39,000 + £65,000 + £116,000 + £180,000 = £400,000 for 2 GWh, i.e. 20 p/kWh average.

Adding non‑commodity fixed cost

Non‑commodity = 2,000 MWh × £30 = £60,000.

Overall annual energy spend = £460,000 or 23 p/kWh.

Benchmark against a pure spot purchase

If the business had taken 100 % spot at the same quarterly averages, commodity cost would be: (6.5 + 7.2 + 5.8 + 9.0) / 4 = 7.125 p/kWh → £142,500 commodity cost. Adding the same £60,000 non‑commodity gives £202,500 total, i.e. 20.3 p/kWh.

The multipurchase contract adds £257,500 (£400,000‑£142,500) in commodity spend but provides price certainty for 1,600 MWh of volume and caps exposure on the remaining 400 MWh. For a finance director, the trade‑off is between a lower average price and the protection against a Q4 spike that could have pushed the spot price above £12 p/kWh, which would have added another £30,000 to the bill.

When to use a multipurchase contract

• Portfolio size 1‑5 GWh – the volume is large enough to negotiate meaningful caps but small enough that a full‑scale bilateral contract is uneconomic.
• Exposure to volatile periods – businesses with a winter heating load benefit from seasonal caps.
• Regulatory reporting – SECR and upcoming DESNZ carbon‑intensity disclosures require a clear baseline, which a fixed non‑commodity component supplies.
• Desire to beat supplier forecasts – TUS has consistently outperformed supplier projections by 20 % over the last 12 months, giving confidence that the caps set are realistic.

Risk management and optimisation

• Review triggers quarterly – market forecasts can shift; adjusting triggers at each renewal keeps the contract aligned with price outlooks.
• Leverage voltage optimisation – a 5‑15 % reduction in demand can be achieved with voltage optimisation, shortening the payback period to 2‑3 years and reducing the volume that needs to be covered by the contract.
• Use the Yolk portal – TUS’s free portal provides real‑time visibility of tranche utilisation and can highlight when a switch to a different supplier could improve the price band. The average switching saving recorded on Yolk is 27 %.

Bottom line

Multipurchase contracts give UK businesses with 1‑5 GWh of annual demand a structured way to cap price spikes while still participating in market lows. By selecting appropriate periods, tranches, caps and triggers, and by fixing non‑commodity costs early, a finance director can align energy spend with budgeting cycles and regulatory reporting. The worked example shows that while the average price may be higher than a pure spot purchase, the protection against extreme spikes and the certainty for capital‑intensive projects often outweigh the incremental cost.