Vehicle-to-Everything Integration Drives China’s Energy Transition
By Li Xiaoming
Institute of Energy and Transportation Integration, Tsinghua University
Published in Journal of Smart Energy Systems, DOI: 10.1016/j.jses.2024.100345
As China accelerates its transition toward a low-carbon future, the convergence of electric mobility and smart energy systems is emerging as a pivotal force reshaping the nation’s power landscape. At the heart of this transformation lies vehicle-to-everything (V2X) technology—an innovative framework that enables bidirectional energy exchange between electric vehicles (EVs), buildings, power grids, and renewable energy sources. This integration is no longer a futuristic concept but a rapidly expanding reality, with pilot projects and policy initiatives demonstrating its technical feasibility, economic viability, and environmental benefits across diverse geographic and operational contexts.
The foundation of this evolution rests on two parallel trends: the explosive growth of distributed photovoltaic (PV) installations and the widespread adoption of electric vehicles. In 2023 alone, China added nearly 100 gigawatts (GW) of commercial and residential rooftop solar capacity, pushing the total installed base to unprecedented levels. While this surge in solar generation contributes significantly to decarbonization, it also introduces new challenges—most notably, the mismatch between solar generation peaks during midday and electricity demand peaks in the evening. This imbalance has led to grid congestion, voltage fluctuations, and even negative electricity prices in regions like Shandong, where solar penetration has outpaced grid flexibility.
Simultaneously, China’s EV fleet has surpassed 20 million units, with over 80% of vehicles parked near buildings for more than 90% of the time. This high utilization of stationary EVs presents a unique opportunity: leveraging their batteries not just for transportation, but as mobile energy storage units capable of absorbing excess solar power and discharging it when demand rises. This concept, known as vehicle-to-building (V2B) or vehicle-to-grid (V2G), is now being operationalized through integrated energy systems that combine solar generation, fixed energy storage, and flexible building loads.
One of the most promising architectures to emerge is the photovoltaic-storage-direct current-flexible load (PV-Storage-DC-Flex) system, often referred to as “light-storage-direct-flex” in Chinese policy and technical discourse. These systems utilize direct current (DC) microgrids to integrate rooftop solar panels, EV charging stations, stationary battery storage, and DC-compatible appliances such as LED lighting and heat pump air conditioners. Because solar panels, batteries, and EVs are inherently DC devices, minimizing AC/DC conversion losses improves overall system efficiency by up to 15%, according to field studies conducted in Beijing and Zhuhai.
In a commercial office building in Beijing, a 375V/48V DC microgrid integrates 20 kilowatts (kW) of rooftop solar, three 6.6kW bidirectional DC chargers, and a building management system that coordinates lighting and HVAC operation. During sunny midday hours, solar energy directly powers building loads and charges EVs parked in the underground garage. When solar output exceeds demand, surplus energy is stored in both the building’s fixed battery system and the parked EVs. In the evening, as grid demand rises, EVs with sufficient state of charge (SoC) discharge energy back into the building, reducing peak load and avoiding high time-of-use tariffs. The system has demonstrated a 35% reduction in grid electricity consumption and a 42% decrease in peak demand charges.
Similarly, in a residential complex in Zhuhai, a 400V/48V DC microgrid combines 5kW of solar PV, a 6.6kWh stationary lithium-ion battery, and EV charging infrastructure. The system employs dynamic load management to shift air conditioning usage to midday, aligning with solar generation. EVs are charged preferentially during solar surplus periods and can supply power back to the grid during evening peaks. Over a six-month trial, the system achieved a 90% self-consumption rate for solar energy and reduced the building’s reliance on the main grid by 58% during peak hours.
These case studies highlight a critical insight: EVs are not merely consumers of electricity but active participants in grid balancing. When aggregated, their collective battery capacity can rival or exceed that of centralized storage facilities. However, realizing this potential requires more than just technology—it demands a rethinking of infrastructure, regulation, and market design.
China’s approach to scaling V2X is guided by a “point-line-surface” (dian-xian-mian) spatial strategy that aligns energy infrastructure development with regional economic and geographic characteristics. This framework recognizes that different regions face distinct energy challenges and opportunities, necessitating tailored solutions rather than a one-size-fits-all model.
At the “point” level, remote industrial zones and resource extraction sites are transforming into zero-carbon energy hubs. In Ordos, Inner Mongolia, the Dishigou open-pit coal mine has launched a smart zero-carbon mining project that replaces diesel-powered haul trucks with 50 electric mining vehicles—12 battery-charging and 38 battery-swapping units. The site is supported by six fast-charging stations and a battery swap station, enabling continuous operation with minimal downtime. To power this electrified fleet, a solar farm has been constructed on reclaimed land, generating clean electricity that offsets approximately 2.7 million liters of diesel annually. This closed-loop system not only reduces emissions but also addresses the challenge of grid expansion in remote areas, where infrastructure investment is often cost-prohibitive.
Beyond mining, oil fields are also embracing this model. In Daqing, Heilongjiang, the Lamadian oilfield has developed a 350 million kWh/year wind and solar complex, covering 30% of the facility’s electricity needs. The project includes a pilot hydrogen production unit with a capacity of 1,000 cubic meters per hour, using surplus renewable energy to produce green hydrogen. This hydrogen is then blended into existing natural gas pipelines, creating a hybrid energy transport system that complements high-voltage transmission lines. The long-term vision is a “solar-storage-charging-hydrogen-vehicle” ecosystem that supports not only oilfield operations but also attracts high-energy-demand industries such as data centers, fostering regional economic diversification.
The “line” dimension focuses on transportation corridors, particularly long-haul freight routes where electric heavy-duty trucks are replacing diesel counterparts. The Chengdu-Chongqing economic corridor, spanning 365 kilometers, has become a national model for electric freight logistics. Six battery swap stations have been deployed along the route, enabling electric trucks to exchange depleted batteries for fully charged ones in under five minutes. This system, which supports interoperability across different vehicle models and battery manufacturers, has reduced logistics costs by over 30% under full operational load. Solar panels installed on station rooftops and roadside slopes provide partial charging for the spare battery inventory, reducing grid dependence.
In the Ningde-Xiamen freight corridor, a similar network of four swap stations covers 420 kilometers, demonstrating cross-brand compatibility and dynamic battery scheduling. These “light-storage-charging-swap-hydrogen” stations are evolving into multifunctional energy nodes that not only serve vehicles but also provide grid services such as frequency regulation and peak shaving. When demand is low, spare batteries are charged using low-cost or surplus renewable energy; during peak hours, they discharge back to the grid, enhancing overall system flexibility.
The “surface” scenario applies to densely populated urban areas in eastern and central China, where cities are becoming laboratories for integrated energy management. In Shenzhen, a leading smart city, the municipal virtual power plant (VPP) platform has connected over 90 charging stations and more than 30,000 distributed energy resources, including building HVAC systems, telecom base stations, and EV fleets. Since its launch, the platform has participated in over 30 demand response events, delivering more than 400,000 kWh of flexible capacity to the grid. EVs play a central role in this ecosystem, acting as both load-shifting assets and emergency backup sources.
What makes the Shenzhen model particularly scalable is its aggregation mechanism. Instead of relying on individual vehicle owners to respond to grid signals, the VPP platform works with fleet operators, property managers, and charging service providers to coordinate thousands of devices simultaneously. Algorithms predict vehicle availability, battery health, and travel patterns to optimize charging and discharging schedules without compromising mobility needs. For example, delivery vans that return to depots in the afternoon can be charged using solar power and then discharge during the 7–9 PM peak, when electricity prices are highest.
Beyond technical coordination, the success of V2X depends on policy and market incentives. In 2023, the National Development and Reform Commission revised its renewable energy procurement policy, moving away from guaranteed full purchase mandates toward market-based mechanisms. This shift places greater emphasis on self-consumption and flexibility, incentivizing prosumers—consumers who also produce energy—to adopt storage and demand response solutions. EVs, with their dual role as transport and storage, are uniquely positioned to benefit from this transition.
However, challenges remain. One major barrier is the lack of standardized bidirectional charging infrastructure. While CHAdeMO and CCS Combo connectors support V2G in some markets, China’s dominant GB/T standard has only recently introduced bidirectional capabilities. Widespread deployment of V2G-enabled chargers and vehicle onboard chargers will require significant investment and coordination between automakers, charging operators, and utilities.
Battery degradation is another concern. Frequent charging and discharging cycles can accelerate wear, potentially affecting vehicle warranty and resale value. To address this, researchers at Tsinghua University are developing adaptive charging algorithms that minimize stress on battery cells while maximizing grid service value. Early results show that with proper thermal management and state-of-charge window control, V2G operations can be conducted with less than 2% additional degradation over a five-year period.
Consumer acceptance is equally critical. Many EV owners remain unaware of V2X benefits or fear that discharging their vehicle could leave them stranded. Education campaigns, transparent user interfaces, and financial incentives—such as reduced electricity rates or direct payments for grid services—are essential to building trust. Pilot programs in Jiangsu and Zhejiang provinces have shown that when users receive real-time feedback and monetary rewards, participation rates exceed 70%.
Looking ahead, the integration of EVs into the energy system will deepen with advances in artificial intelligence, 5G connectivity, and digital twin modeling. Smart charging platforms will evolve into comprehensive mobility-energy managers, coordinating not just EVs but also home appliances, solar inverters, and even hydrogen fuel cell vehicles. The boundary between transportation and energy infrastructure will blur, giving rise to a new paradigm: mobility-as-a-service meets energy-as-a-service.
In rural areas, the impact could be transformative. In Ruicheng County, Shaanxi Province, the Zhuangshang Village project has installed 2,000 kW of rooftop solar across 156 households. To manage surplus generation, the village deployed a 717 kWh battery storage system. As more residents adopt electric bikes, tricycles, and cars with bidirectional charging, the combined mobile storage capacity is expected to triple within five years. This “hybrid battery” system—combining fixed and vehicle-based storage—will enable the village to achieve near-total energy self-sufficiency, even during winter months with limited sunlight.
The implications extend beyond energy security. By turning EVs into income-generating assets, V2X can improve the economics of vehicle ownership, particularly for fleet operators and ride-hailing drivers. A taxi driver in Hangzhou, for instance, could earn several hundred yuan per month by allowing their vehicle to provide grid services during idle periods. For automakers, this opens new revenue streams through energy management subscriptions and value-added services.
Ultimately, the vehicle-energy nexus represents more than a technological upgrade—it is a systemic shift toward a decentralized, resilient, and sustainable energy future. As China continues to build out its EV charging network and modernize its power grid, the integration of mobility and energy will become a cornerstone of national strategy. From remote mines to urban skyscrapers, from freight highways to suburban homes, the car is no longer just a means of transport but a mobile power plant, a grid stabilizer, and a catalyst for regional revitalization.
The journey is still in its early stages, but the trajectory is clear. With continued innovation, supportive policies, and public engagement, vehicle-to-everything integration will play a defining role in China’s energy transformation—one kilowatt-hour at a time.
Li Xiaoming
Institute of Energy and Transportation Integration, Tsinghua University
Journal of Smart Energy Systems, DOI: 10.1016/j.jses.2024.100345