I. The Essence of the Electricity Spot Market: A Special Market for Real-Time Electricity Trading
Imagine you own a restaurant (electricity consumer). You need to purchase fresh vegetables (electricity) daily. Electricity, as a special commodity, is difficult to store on a large scale and must be used immediately upon generation. This gave rise to the electricity spot market, whose core function is to achieve real-time balance between electricity supply and demand. The market is typically divided into three trading sessions:
- Morning Session (Day-ahead Market): The electricity consumption plan and prices for 96 time slots (each 15 minutes) are determined one day in advance, locking in approximately 80% of the electricity consumption.
- Afternoon Session (Intraday Market): Purchase quantities are flexibly adjusted according to actual demand on the same day.
- Emergency Replenishment (Real-Time Market): Emergency transactions to handle unforeseen circumstances, with electricity prices updated every 5 minutes and settlement cycles as short as 5 minutes to 1 hour.
II. The Three-Step Mechanism for Electricity Price Formation
- Day-ahead Market: “Planned Purchases” One Day in Advance
① Operation Method: Prices for 96 time slots (each 15 minutes) are determined one day before electricity consumption.
② The photovoltaic power station anticipated good sunshine the following noon and quoted a price of 0.28 yuan/kWh. The final price for that period was set at 0.32 yuan/kWh. (Based on the final winning bid from the coal-fired power unit.)
- Intraday Market: Flexible Adjustment within the Same Day
① Trading Frequency: Adjusted every 4 hours
② Real-world Case: The photovoltaic power station discovered that its midday power generation exceeded expectations. The extra 10,000 kWh was sold at 0.28 yuan/kWh to avoid waste.
- Real-time Market: Responding to Sudden “Emergency Replenishment”
① Characteristics: Pricing is set 5 minutes to 1 hour before delivery, updated every 5 minutes.
② Extreme Case: A sudden drop in temperature due to overcast skies increases electricity demand. The gas-fired power unit offers emergency power at 1.7 yuan/kWh (6 times the usual price). Energy storage units can also be sold at 1.7 yuan/kWh for a significant profit.
III. Two Core Rules of Electricity Pricing
- Marginal Pricing: The Last Generator Determines the Overall Price
The system allocates power sources from lowest to highest generation cost until load demand is met. All electricity transactions are settled based on the price quoted by the last generator unit used.
Example: Like group buying, if 300,000 kWh of electricity is needed at a certain moment, the allocation order is:
① New Energy (PV/Wind Power): Cost 0.2 yuan/kWh, providing 100,000 kWh.
② Coal Power: Cost 0.3 yuan/kWh, providing 150,000 kWh.
③ Gas-fired Power: Cost 0.8 yuan/kWh, providing 50,000 kWh.
In this case, all electricity transactions are settled at 0.8 yuan/kWh, resulting in excess profit for the new energy generator unit.
- Nodal Pricing: Regional Price Differences Due to Transmission Congestion
Electricity transmission is physically limited; line congestion leads to different electricity prices in different regions. For example:
① Due to power line congestion, the electricity price in an industrial park in Shandong reached 0.6 yuan/kWh (including additional congestion costs).
② By adjusting production times to non-congestion periods, enterprises can reduce their annual electricity costs by approximately 400,000 yuan.
IV. Policy Trends in 2025: Focus on Document No. 136 issued by the National Development and Reform Commission
This document further promotes the market-oriented reform of the electricity market, clarifying the timetable and settlement rules for the spot market. Specific details can be found in the supporting documents issued by the energy authorities of each province.
V. Practical Guidelines for Electricity Users
- Weather-Based Electricity Consumption:
Electricity prices are lower at midday when solar power output is high and higher in the evening when solar power output declines. Adjusting production times can reduce electricity costs.
- Combining Contracts and Spot Markets:
It is recommended to lock in prices through long-term contracts for 80% of electricity consumption and participate in the spot market for 20% to obtain price flexibility.
- Site Selection to Avoid Congestion:
New enterprises should avoid areas with congested power grids (e.g., congestion surcharges in some Yangtze River Delta industrial zones can reach 0.2 yuan/kWh), and prioritize locations with a relaxed power grid structure and a high proportion of renewable energy integration.
VI. Listed Companies Related to the Electricity Spot Market
- Guodian Power (600795)
Industry Tags: Thermal Power Transformation, Integrated Renewable Energy Operation
Layout Advantages: Owns large-scale coal-fired power units in multiple spot market pilot provinces, possessing strong peak-shaving capabilities and market pricing experience. It is also actively developing wind power and photovoltaics, benefiting from the profit elasticity under the marginal pricing mechanism.
- Huaneng International (600011)
Industry Tags: Integrated Energy Giant, Leading Market-Based Trading
Layout Advantages: Diversified power structure; can participate in high-price trading through gas-fired units in the spot market; continuously increasing renewable energy installed capacity, adapting to the low-carbon electricity market trend.
- Three Gorges Energy (600905)
Industry Tag: Pure New Energy Operator
Layout Advantages: Primarily focused on wind and solar power, with low generation costs. In marginal pricing markets, it is often prioritized as a power source, obtaining a clearing price higher than its own costs, ensuring a stable profit margin.
- Longyuan Power (001289)
Industry Tag: Leading Wind Power Enterprise
Layout Advantages: Leading domestic wind power installed capacity, participating in spot markets in multiple provinces. Through power forecasting and optimized pricing strategies, it achieves added value in both intraday and real-time markets.
- Southern Power Grid Energy Storage (600995)
Industry Tag: Energy Storage Operation, Peak Shaving Services
Layout Advantages: In the spot market, it can achieve “low-storage, high-generation” through energy storage devices, earning peak-valley price differences. Simultaneously, it provides auxiliary services such as frequency regulation and backup for the system, obtaining multiple revenue streams.
