Level 3 · Electricity Markets · Module 07
How Electricity Prices Are Formed
Why does electricity cost EUR 20/MWh in one hour and EUR 200/MWh in another?
- 4
- connected lessons
- 8
- guided learning steps
- 165
- estimated minutes
The central idea
Why does electricity cost EUR 20/MWh in one hour and EUR 200/MWh in another?
In a marginal market, price is not determined by the average cost of all power plants but by the marginal unit needed to satisfy demand.
In a marginal market, price is not determined by the average cost of all power plants but by the marginal unit needed to satisfy demand. The public preview explains the operating logic, professional relevance and boundaries before the complete guided application.
Professional relevance
Why this matters beyond the classroom.
Trading: understand margin, spreads and tail risk. Generation: connect dispatch and offers to variable cost. Renewables: model capture price rather than baseload headline.
What you will learn
Four lessons that build one working mental model.
- 01
Supply, Demand and the Merit Order
Bids/offers, demand curve, variable cost, dispatch order, marginal unit and market-clearing quantity.
Electricity price is not one annual engineering cost divided by total MWh. Short-term wholesale markets repeatedly answer a narrower question: for this defined interval and area, which offered quantities are accepted to meet demand, given market and network constraints, and at what clearing price? At 03:00, demand may be low, wind high and flexible consumption scarce. At 19:00, demand may peak after solar output falls, while gas units and imports are needed. The physical commodity remains electricity, but scarcity differs. That is why one hour can clear at EUR 20/MWh and another at EUR 200/MWh. This module uses a simplified merit-order model. Actual European market coupling includes complex orders, cross-zonal capacity and algorithmic constraints. The simplified model remains powerful because it explains the core relationship among offers, demand and the marginal accepted unit. For one hour, list available supply offers in ascending price. A stylised stack might contain 1,000 MW wind at EUR -5/MWh, 1,500 MW nuclear at EUR 10, 1,000 MW lignite at EUR 55, 1,200 MW gas combined-cycle at EUR 90 and 500 MW peaker at EUR 180. If demand is 4,000 MW, accepted volumes include wind, nuclear.
- 02
From Fuel and Carbon to Hourly Price
Efficiency/heat rate, fuel price, carbon intensity and allowance cost; start, no-load, opportunity and risk components; why bids need not equal accounting cost.
If a wind unit offers at EUR 0 and the market clears at EUR 100, its gross market revenue is EUR 100/MWh. The difference from its short-run offer/variable cost is an inframarginal rent or contribution margin. This supports recovery of fixed cost and investment and compensates risk. It is not synonymous with net profit. The project may settle a PPA/CfD, pay imbalance and grid costs, suffer curtailment, service debt and bear depreciation/tax. Over a year, low and negative prices reduce average captured revenue. Some plants fail to recover total cost despite positive margins in accepted hours. The marginal plant can also earn contribution if its clearing price exceeds actual variable cost. In a perfectly simplified competitive model, its offer approximates opportunity cost, but real costs and bids are granular. Residual demand is total demand minus output from resources treated as non-dispatchable or price-insensitive in the simplified view. High wind and solar reduce residual demand, pushing the marginal point left toward cheaper offers. Low renewable output or high demand pushes it right toward expensive flexible resources. The evening solar ramp illustrates this. During sunny hours, solar suppresses residual demand and prices..
- 03
Marginal Pricing, Rents and Extreme Prices
Pay-as-clear, inframarginal rent, scarcity, price caps/floors, negative prices, inflexibility, support and opportunity cost.
Capture price is: If solar generates 10 MWh at EUR 20, 20 MWh at EUR 30 and 10 MWh at EUR 80, value is EUR 200 + 600 + 800 = EUR 1,600. Total output is 40 MWh. Capture price is EUR 40/MWh . The simple average of the three hourly prices is EUR 43.33, but generation weighting produces EUR 40. Capture rate divides capture price by a chosen reference average price. If the relevant baseload average is EUR 50/MWh, capture rate is 80%. State the reference, period and zone. Solar plants in one region often generate simultaneously. As capacity grows, their combined output depresses residual demand and price in sunny hours. Each additional project can reduce the price all solar captures. Wind shows similar correlation across weather systems. This is cannibalisation: technology-specific achieved value falls relative to average because its output is correlated with low-price hours. Cannibalisation is not a claim that renewables reduce social value. Low prices benefit consumers and show low marginal-cost supply. For a merchant project, however, revenue depends on actual MWh times achieved capture price. Using annual average baseload price can overvalue it. Storage, geographic.
- 04
Profiles, Capture Price and Cannibalisation
Peak/off-peak, baseload references, price-duration curves, generation-weighted capture price, capture rate and technology correlation.
The supply stack for a bidding zone includes feasible imports and exports, not only domestic plants. If a neighbouring zone has lower-priced supply and cross-zonal capacity is available, coupling can accept imports, displacing a more expensive local unit and bringing prices closer. The interconnector creates value equal to the price difference times flow, subject to rules and losses. When capacity binds, prices can separate. Zone A can clear at EUR 40/MWh and Zone B at EUR 100/MWh because additional low-cost supply cannot reach B. The marginal unit is then zonal within the coupled solution. Saying “gas set the European price” is too broad unless product, hour and zone are identified. Flow-based capacity calculation recognises that exchanges affect multiple network elements through different paths. The market result respects the capacity inputs and allocation constraints. Internal congestion can still require redispatch after zonal clearing. The cost of that redispatch is not automatically visible in the zonal day-ahead price. Imports are not a technology. Their price reflects the exporting zone’s marginal conditions, capacity scarcity and coupling. A country can import while operating expensive domestic units because network constraints and local security require both..
Key takeaways
What should remain after the details.
- Hourly scarcity changes price.
- Merit order sorts available offers, not permanent technology labels.
- The marginal accepted unit sets the simplified uniform price.
- Price is not average cost or net profit.
- Fuel, efficiency and carbon shape thermal marginal cost.
- Inframarginal rent helps recover fixed cost and risk.
- Scarcity prices reward flexibility and availability.
- Negative prices reveal inflexibility or excess supply relative to demand/network flexibility.
Correct the shortcut
Common misconceptions
- Price equals average generation cost. It reflects the marginal accepted offer in the simplified model.
- This shortcut is incomplete; apply the module’s definitions, system boundary and operating constraints before drawing a conclusion.
- Renewables always set price at zero. They often shift the margin; another unit may set price.
- This shortcut is incomplete; apply the module’s definitions, system boundary and operating constraints before drawing a conclusion.
- Inframarginal rent is net profit. Fixed costs, contracts and risks remain.
- This shortcut is incomplete; apply the module’s definitions, system boundary and operating constraints before drawing a conclusion.
- High price proves abuse. Scarcity can be legitimate; evidence is required.
- This shortcut is incomplete; apply the module’s definitions, system boundary and operating constraints before drawing a conclusion.
- Negative price means free retail electricity. It is one wholesale component.
- This shortcut is incomplete; apply the module’s definitions, system boundary and operating constraints before drawing a conclusion.
Worked reasoning
Worked 6-hour market
Demand across six hours is 2, 3, 4, 5, 4 and 3 GW. Solar output is 0, 0.5, 1.5, 2, 0.5 and 0 GW. Wind is 1 GW throughout. Other offers: nuclear 1 GW at EUR 10, coal 1 GW at EUR 60, gas 2 GW at EUR 100 and peaker 1 GW at EUR 200. At hour 1, residual demand after wind is 1 GW, filled by nuclear: price EUR 10. At hour 4, residual demand after wind and 2 GW solar is 2 GW: nuclear plus coal, price EUR 60. If solar were unavailable, residual demand would be 4 GW, requiring gas and price EUR 100. Solar lowered the marginal unit. But solar earns only in its production hours. If prices during high solar output are systematically EUR 20-60 while evening reaches EUR 200, solar capture price lies below baseload average. A battery could charge during solar hours and discharge later, subject to losses and constraints.
Concept map
The vocabulary this module connects.
- Bids/offers
- demand curve
- variable cost
- dispatch order
- marginal unit and market-clearing quantity.
- Efficiency/heat rate
- fuel price
- carbon intensity and allowance cost; start
- no-load
- opportunity and risk components; why bids need not equal accounting cost.
- Pay-as-clear
- inframarginal rent
- scarcity
- price caps/floors
- negative prices
- inflexibility
- support and opportunity cost.
- Peak/off-peak
- baseload references
- price-duration curves
- generation-weighted capture price
- capture rate and technology correlation.
Evidence boundary
Selected authoritative sources
Research reviewed 2026-08-13. The complete learning package contains the full reference trail and explains where simplified beginner models stop.
- Regulation (EU) 2019/943, consolidated text - price formation and market principlesResearch source used in the How Electricity Prices Are Formed learning package
- European Commission, Electricity market design and marginal pricingResearch source used in the How Electricity Prices Are Formed learning package
- European Commission, Electricity prices and driversResearch source used in the How Electricity Prices Are Formed learning package
- ACER, Electricity Market Monitoring ReportResearch source used in the How Electricity Prices Are Formed learning package
- ENTSO-E Transparency Platform, generation, load and price dataResearch source used in the How Electricity Prices Are Formed learning package
Questions answered
How Electricity Prices Are Formed FAQ
Why does electricity cost EUR 20/MWh in one hour and EUR 200/MWh in another?
In a marginal market, price is not determined by the average cost of all power plants but by the marginal unit needed to satisfy demand.
Why does how electricity prices are formed matter to energy professionals?
Trading: understand margin, spreads and tail risk. Generation: connect dispatch and offers to variable cost. Renewables: model capture price rather than baseload headline.
What will I learn in this How Electricity Prices Are Formed module?
You will connect Bids/offers, demand curve, variable cost, dispatch order, marginal unit and market-clearing quantity.; Efficiency/heat rate, fuel price, carbon intensity and allowance cost; start, no-load, opportunity and risk components; why bids need not equal accounting cost.; Pay-as-clear, inframarginal rent, scarcity, price caps/floors, negative prices, inflexibility, support and opportunity cost.; Peak/off-peak, baseload references, price-duration curves, generation-weighted capture price, capture rate and technology correlation..
What remains inside the complete learning module?
The complete module contains the full readings, guided decisions, feedback, mastery assessment and professional challenge, with progress recorded in the learner experience.
Learn, apply, test
Reading is only the beginning.
The complete module adds guided decisions, feedback, a mastery assessment and a professional challenge. Your progress remains in your learner dashboard.