How do the models
for your
electricity purchase differ?
Compare fixed price, tranches, spot market and hybrid models: When is the price fixed, what risks remain, and what tasks arise within the company?
You'll learn which model sets prices early, which reacts continuously to the market, and which decisions ultimately rest with you. Three calculation examples demonstrate how a later price affects quantities already partially purchased. This allows you to scrutinize offers more effectively.
Compare modelsThen the pricing logic.
For example: Full supply of the agreed delivery points and their needs – according to the contract rules.
- Fixed price
- Staged purchasing
- Spot procurement
- Mixed model
Full supply is
a different question
than a fixed price.
One supplier covers the agreed-upon demand. How the price is determined will be regulated separately.
In common parlance, "full supply" is often associated with a fixed-price offer. Therefore, when comparing offers, ask two separate questions: Does the supplier cover my agreed-upon requirements, and under what rule are these requirements billed? Full supply can involve a fixed price or a formula-based price. Whether or not staggered procurement is incorporated also depends on the specific product.
A public example of this distinction is Uniper's full-service energy supply at a fixed or formula price. The description refers to products for industrial companies and regional energy providers. The distinction is clear: the same scope of supply can be offered with different pricing rules. You can clarify which option is available for your business in the specific offer.
Check delivery points, quantity ranges, excess and shortfall quantities, forecasting obligations, and the handling of own generation or third-party quantities. A comprehensive delivery scope does not negate these conditions.
Likewise, full supply is not synonymous with basic or substitute supply. An individual commercial supply contract requires its own review. The offer should clearly state who is responsible for procurement and processing, which risks are factored in, and which remain with the company.
Four ways to distribute price risks
.
The differences concern the energy share and its contractual representation. Network, metering, taxes, charges, and other components must also be examined.
A price basis
is determined early on.
In a fixed-price model, certain price components are fixed for an agreed period. If the contract is concluded on a specific date, this price basis depends on that exact point in time.
- Predictability
- High for the components that are actually fixed; the total annual bill still depends on the quantity and other components.
- weighing of options
- Subsequent market price declines do not usually automatically affect the fixed portion.
Take a closer look at the offer
What components are covered by the guarantee? For what quantity and for what period does it apply? How are deviations calculated? A fixed price is not proof that the purchase was cheapest in hindsight.
Multiple points in time.
One purchasing framework.
The demand is divided into partial quantities, which are procured at different times. This prevents the decision from being concentrated on a single transaction. However, any remaining quantities are still dependent on future market prices.
- Predictability
- It increases with the completed tranches. The final blended price will only be determined once all relevant prices are known.
- weighing of options
- In a consistently rising market, later purchases can be more expensive. Making more purchases at different times does not eliminate the price risk.
Rules and possible AI support
Before the first purchase, agree on volume shares, purchasing windows, deadlines, responsibilities and risk limits. In rule-based models, AI analysis can help evaluate market signals. Suspending purchases leaves unhedged volumes exposed to the market; it does not ensure a more favorable price path.
The specific variants are explained in the Guide to the Tranche Strategy.
Buy continuously.
Bear the effects of market movements.
A spot model follows short-term prices according to a defined contract formula. Day-ahead trading involves trading the delivery intervals of the following day; intraday trading allows for adjustments closer to delivery. Your company does not need to trade on the energy exchange itself for this to work.
- Market participation
- Falling and rising prices can change the as-yet-unfixed energy share. Price risks remain relevant throughout the delivery period.
- weighing of options
- The key factors are the index used, the load profile, the billing rule, and additional charges.
What "flexible" means here
A variable price does not automatically mean a short contract term or arbitrary changes in quantity. Shifting loads only helps if the contract includes time-dependent pricing and the company can practically manage the shift.
View published day-ahead prices · Market fundamentals at SMARD
Secure part of it.
Keep part of it open.
A hybrid model combines fixed and variable procurement. This can be achieved through quantity percentages, a supply band, or other contractually defined parameters. Have it explained to you what these percentages refer to: your projected annual quantity or a supply band agreed upon for specific hours. This will determine how excess demand or surpluses are handled.
- Predictability
- Available for the fixed part; the variable part remains exposed to market movements.
- weighing of options
- A larger variable component increases the influence of later prices – in both directions.
A percentage needs a reference basis.
"60 percent fixed" can refer to a forecasted energy quantity. A constant delivery band, on the other hand, is a temporal power structure. These two representations are not necessarily the same. Examine how additional demand and surpluses are handled.
There is no standard quota that applies to all companies. The following pricing scenarios use a fixed quantity distribution; they do not determine a suitable quota for your business.
The key
differences at a glance.
This assessment does not replace the terms and conditions of the offer. It shows which questions you should ask when comparing offers.
On narrow screens, the table can be moved sideways.
| Model | When does the price become known? | Later market opportunities | Significant outstanding risk | Organization within the company |
|---|---|---|---|---|
| Fixed price | For the components fixed when the contract is signed. | There is usually no automatic participation on the fixed share. | Purchase date, quantity changes and excluded components. | Carefully review the offer, the commitment, and the contract deadlines. |
| Staged purchasing | Step by step; the mixed price is derived from the completed partial quantities. | For tranches not yet purchased, depending on later purchases. | Unpriced volumes, procurement deadlines and an unfavourable market trend. | Track rules, responsibilities, and progress. |
| Spot market | Short-term according to index and billing rule. | Falling prices can be passed on; rising prices can too. | Price and profile impact during delivery. | Monitor budget fluctuations, billing, and load profile. |
| Hybrid | Early for the fixed part; later for the variable part. | Limited to the contractually agreed market-related share. | Variable proportion and allocation of excess and shortfall quantities. | Understand the allocation and adjustment rules. |
It describes a scope of delivery that is combined with a specific pricing logic and quantity rule. Likewise, cancellation rights and contract duration must be examined separately for each model.
Three time specifications.
Three different tasks.
An offer only becomes clear when purchasing, delivery, and price guarantees are clearly assigned.
- 01
Procurement period
When are quantities permitted or required to be purchased? Are there fixed purchase dates, a time window, or a deadline for quantities not yet purchased?
- 02
Delivery period
For which days, months, or years is the energy intended? A tranche purchased today can secure a later delivery period.
- 03
Contract and price guarantees
How long is the supply contract binding? Which components are fixed and for how long? A price guarantee does not replace the examination of the contract duration and its renewal rules.
A longer-term commitment can make the fixed components more predictable over a longer period, but it restricts future changes. In the case of relocation, a new production line, or additional own generation, it's also important to consider what changes in quantity and location are permitted. The contract structure should align with the company's development plan.
The futures market includes monthly, quarterly and annual products. These standard products are not identical to your company’s individual supply contract. A future does not necessarily lead to physical delivery either: settlement depends on the product specification. EEX describes the maturities and settlement of its power futures.
60% purchased.
What happens to
the remaining 40%?
The allocation is already fixed in this example. Three possible future prices simultaneously show how the open quantity affects the pure procurement costs. You don't need to enter anything.
The specific effect: If the price of the open quantity changes by €10/MWh, the mixed price here changes by €4/MWh – so by €400 for 100 MWh. This applies both upwards and downwards.
The same starting point applies in all three cases.
100 MWh total demand for the same delivery period, fully consumed. 1 MWh corresponds to 1,000 kWh. The 60/40 split is an arbitrary calculation assumption, not a recommendation.
The fixed and open quantities together amount to 100 MWh.
60 €/MWh
- Fixed 60 MWh
- 6,000 €
- Open 40 MWh
- 40 MWh × 60 €/MWh = €2,400
- Total procurement costs
- 6.000 € + 2.400 € = 8.400 €
MIXED PRICE84 €/MWh8,400 € ÷ 100 MWh
100 €/MWh
- Fixed 60 MWh
- 6,000 €
- Open 40 MWh
- 40 MWh × 100 €/MWh = 4,000 €
- Total procurement costs
- 6.000 € + 4.000 € = 10.000 €
MIXED PRICE100 €/MWh10,000 € ÷ 100 MWh
160 €/MWh
- Fixed 60 MWh
- 6,000 €
- Open 40 MWh
- 40 MWh × 160 €/MWh = 6,400 €
- Total procurement costs
- 6.000 € + 6.400 € = 12.400 €
MIXED PRICE124 €/MWh12,400 € ÷ 100 MWh
A calculation method for all three cases
Procurement costs = 60 MWh × €100/MWh + 40 MWh × scenario price in €/MWh
Mixed price in €/MWh = Procurement costs in € ÷ 100 MWh
It cannot be deduced from this: which quota is suitable for your company, which price will prevail, or which model will be more economical. All prices are hypothetical. For the open quantity, an already consumption-weighted average price is assumed; this is not an unweighted market average. Only the net procurement share is considered. Network charges, taxes, levies, metering, supplier fees, as well as profile and quantity deviations are not included.
To make a truly informed decision, your previous purchasing history, contract terms, load profile, and budget are all relevant. Prepare these documents and questions for the meeting
The daily routine of operations
dictates the test questions.
One industry alone does not determine a procurement model. These examples illustrate different requirements, not an automatic tariff recommendation.
Skilled trades, offices and commerce
When energy procurement is one of many tasks, clear pricing rules and manageable decision-making are crucial. Determine which budget components need to be finalized early and who is responsible for keeping track of deadlines. A small annual volume is neither an inherent advantage nor disadvantage of any particular model.
Production and energy-intensive processes
Load profiles, shift schedules, and planned plant modifications make the risk tangible. Continuous processes cannot be arbitrarily switched to favorable intervals. Before considering a variable component, the budget impact, operational flexibility, and responsibilities must be understood.
Catering, refrigeration and seasonal needs
Opening hours and temperature influence demand, but cold chains and quality impose limitations. A seasonal operation should therefore describe both the annual volume and its distribution over time. Annual averages can mask high costs in individual months.
Multiple locations and organizations
Different contract durations and metering concepts first require an overview of delivery points. A common framework does not necessarily mean the same pricing approach for every location. For property and condominium management companies, OPTUM prioritizes fixed-price offers and reliable portfolio processes.
Six answers
before choosing a model.
Check off what you already know. You can bring up any remaining questions in the meeting – you don't need to have all the documents yet. The list will help you determine the next step.
0 out of 6 points prepared.
Preparing for a procurement meetingThis is often confused.
Does a fixed price also guarantee the annual costs?
No. A fixed price per kWh does not automatically mean a fixed billing amount. If your business consumes more electricity, your energy costs will increase even with the same energy charge. Additionally, excluded price components and quantity rules can affect the final result. For budgeting purposes, both the quantity and the complete pricing structure must be considered together.
Are tranches generally cheaper than a fixed price?
No. They spread purchasing decisions over several points in time. Whether the resulting price is more favorable in retrospect depends on the actual market performance and the quantities chosen. A rising market can favor an early, complete purchase, while a falling market favors later purchases.
Can a company cancel a spot price agreement at any time?
Pricing alone doesn't answer this question. Contract duration, notice period, and renewal terms are stipulated in the supply agreement. A short-term electricity exchange price may be linked to a longer contractual commitment.
Does a negative electricity exchange price mean free energy?
A negative exchange price relates to a specific trading and delivery situation. The supply contract determines whether and how it is passed on. Other price components still apply; the total bill does not automatically become zero or negative.
What is included in the quantity-weighted or consumption-weighted price?
Each price is multiplied by the corresponding energy quantity. The sum of these amounts is then divided by the total energy quantity. For tranches, these are the sub-quantities; for the time-resolved spot model, they are the quantities of the respective intervals. kW is a unit of power and must not be used like kWh or MWh without a time reference.
From understanding
to the next step.
Sources and assessment
Market terms: Federal Network Agency | SMARD. Futures products: EEX Power Futures. Example of separate delivery and pricing logic: Uniper balancing group. Retrieved on September 14, 2026.
The comparison questions and calculation assumptions are editorial explanations provided by OPTUM. Availability and terms of a specific contract must be checked separately. None of the models guarantees the lowest price.
Additionally, check how the contract terms handle quantity deviations.
Understanding quantity bands, excess and shortfall quantities →
