2026-05-21
Driven by both the rapid adoption of new energy vehicles and the development of new power systems, “vehicle-grid interaction” is no longer a distant concept, NIO CEO William Li has publicly praised S2G battery swap stations for their capabilities in “reverse power supply and peak shaving and valley filling,” sparking widespread discussion. Meanwhile, the more widely known V2G technology is also accelerating its deployment with policy support. S2G (Station-to-Grid) and V2G (Vehicle-to-Grid) battery swap stations are becoming core platforms for the integration of “transportation - energy.” They serve not only as rapid energy replenishment stations for electric vehicles, but also as distributed energy storage “power banks” for the grid. Both support bidirectional power flow, but differ significantly in their interaction entities, control modes, and application scenarios. Below is a comprehensive interpretation of S2G and V2G battery swap stations from five dimensions: definition, operating principle, differences, value, and real-world cases.
I. V2G Battery Swap Stations: Bidirectional Vehicle-Grid Interaction, Turning Vehicles into “Mobile Energy Storage”
1. Core Definition
A V2G (Vehicle-to-Grid) battery swap station is a battery swap station equipped with bidirectional charging and discharging equipment. Its core function is direct two-way interaction between vehicle batteries and the power grid: charging from the grid and storing energy during off-peak periods, while feeding electricity from vehicle batteries back to the grid during peak periods, turning every electric vehicle into a “mobile energy storage unit.”
2. Operating Principle
Forward Power Flow (Charging): During off-peak grid periods (such as at night), when electricity prices are low, the battery swap station fully charges vehicle batteries through bidirectional charging piles to meet users’ daily travel needs.
Reverse Power Flow (Discharging): During peak grid periods (such as in the evening), when electricity demand is high and electricity prices rise, after receiving user authorization, vehicle batteries can feed electricity back to the grid through V2G charging piles, helping the grid achieve peak shaving and valley filling while allowing vehicle owners to earn revenue from peak-valley electricity price differences.
Intelligent Dispatching: Based on an energy management platform, grid load, electricity prices, and vehicle battery swap demand are synchronized in real time. Charging and discharging strategies are automatically planned to balance users’ energy replenishment needs with grid regulation requirements.
3. Core Features
Interaction Entity: Vehicle battery ↔ power grid, with distributed interaction based on individual vehicles.
Discharge Power: The discharge power of a single vehicle is limited (typically tens of kilowatts), requiring the aggregation of multiple vehicles to achieve a significant scale effect.
Applicable Scenarios: Public charging and battery swap stations and community charging stations, suitable for distributed electric vehicles such as private cars and ride-hailing vehicles.
II. S2G Battery Swap Stations: Centralized Station-Grid Interaction, Turning Stations into “Giant Energy Storage Systems”
1. Core Definition
S2G (Station-to-Grid) battery swap stations integrate a large-scale backup battery bank + station-level energy management system. Their core function is centralized bidirectional interaction between the entire battery swap station and the power grid: all idle backup batteries within the station are coordinated to store electricity during off-peak periods and discharge centrally during peak periods, making each station equivalent to a “giant energy storage power station.”
2. Operating Principle
Centralized Energy Storage (Off-Peak): During off-peak grid periods, the battery swap station centrally charges its backup batteries (typically 20-50 sets). Once fully charged, they are intelligently managed without affecting users’ battery swap demand.
Centralized Discharging (Peak Period): During peak grid periods, the station control system dispatches all idle backup batteries to feed electricity back to the grid at scale and with high power. A single station can reach a discharge power of 400-600 kW, equivalent to more than ten V2G vehicles discharging simultaneously.
Demand Forecasting and Balancing: The AI system predicts the day’s peak battery swap demand in advance, reserves sufficient available batteries, and allows the remaining idle batteries to fully participate in grid peak regulation, providing dual assurance for “battery swap services + grid regulation.”
3. Core Features
l Interaction Entity: Battery swap station battery bank ↔ power grid, with centralized interaction based on a single station.
l Discharge Power: High power per station (400kW+), with fast control response, enabling direct participation in ancillary grid services such as frequency regulation and peak shaving.
l Applicable Scenarios: High-traffic battery swap stations in highway service areas, urban core areas, and similar locations, suitable for large-scale battery swap networks such as NIO and Aulton.
III. Core Area of S2G and V2G Battery Swap Stations
IV. Core Value: More Than Energy Replenishment, a New “Infrastructure” for Energy Integration
1. For the Power Grid: Peak Shaving and Valley Filling, Stabilizing Loads and Reducing Costs
l Relieve peak-period power supply pressure and reduce investment in grid expansion; absorb surplus electricity during off-peak periods and improve renewable energy utilization.
l S2G battery swap stations can quickly respond to grid dispatching, participate in frequency regulation and emergency power supply, and enhance the stability of new power systems.
2. For Users: Lower Costs and Higher Returns
l V2G: Vehicle owners charge at low prices during off-peak periods and sell electricity at higher prices during peak periods, reducing vehicle operating costs while generating additional income.
l S2G: Fast battery swapping (3-5 minutes), eliminating charging wait times. Sufficient backup batteries also provide a more stable battery swap experience.
3. For Operators: Higher Revenue + Greater Efficiency, Creating a Closed-Loop Business Model
l Arbitrage from peak-valley electricity price differences + subsidies for grid ancillary services create a second revenue stream for battery swap stations.
l Improve battery utilization, extend battery life, reduce operating costs, and enhance the competitiveness of battery swap networks.
4. For the Industry: Promoting Integrated “Vehicle - Station - Grid” Development
l Integrate energy flow, data flow, and business flow to build a “V2S2G” (Vehicle - Battery Swap Station - Grid) full-chain interactive ecosystem.
l Promote deeper integration between new energy vehicles and new power systems, accelerating the achievement of “dual-carbon” goals.
V. Real-World Cases: From Demonstration to Large-Scale Deployment, the Technology Is Already Mature
1. China’s First S2G Battery Swap Station in Regular Operation: NIO Battery Swap Station at Nanjing Fangshan Service Area
l Configuration: 21 sets of backup batteries, with a total capacity of 1600kWh and a maximum discharge power of 410kW.
l Operation: Regular discharging began in September 2025, with cumulative discharged electricity exceeding 5200kWh and daily revenue of approximately RMB 206 (excluding subsidies).
2. V2G Demonstration Benchmark: CATL Super Charging and Battery Swap Station
l Configuration: Bidirectional V2G charging and discharging piles, supporting reverse vehicle discharge during peak periods and ultra-fast battery swapping in 105 seconds.
l Functions: Integrated photovoltaic generation, energy storage, charging, battery swapping, discharging, and inspection, enabling bidirectional interaction between vehicle batteries and the power grid and supporting the development of virtual power plants.
CATL Super Charging and Battery Swap Station
3. Large-Scale Deployment: NIO and Aulton Accelerate V2G/S2G Implementation
l NIO: More than 2,000 battery swap stations nationwide are equipped with V2G/S2G capabilities, with 310 million kWh of electricity shifted during peak periods in 2024.
l Aulton: Independently developed V2S2G technology creates a closed-loop connection between vehicle - station - grid, with total energy storage capacity across its battery swap stations exceeding 4.2GWh.
VI. S2G and V2G Are Not Opposing Technologies, but Complementary and Symbiotic
Simply put, V2G battery swap stations are the “capillaries” of vehicle-grid interaction, using individual vehicles as distributed energy storage units for flexible interaction and making them suitable for scenarios such as private vehicles; S2G battery swap stations are the “arteries” of station-grid interaction, using entire stations as centralized energy storage systems for efficient regulation, making them suitable for core sites in large-scale battery swap networks.The two are not mutually exclusive, but complementary and collaborative, jointly forming an integrated “vehicle - station - grid” energy replenishment and energy regulation system. This represents an inevitable trend in the future integration of the new energy vehicle and power industries.
