Research on Low-Cost Construction of EV Charging Stations at Gas Stations

The Landscape of Charging Station Construction and Development for Refined Oil Sales Companies

• Rapidly Increasing Market Penetration of NEVs

In the Chinese market, for instance, the market penetration rate of new energy vehicles (NEVs) has witnessed exponential growth, surging from 5.8% in 2020 to 47% in 2024, capturing nearly half of the new car market (Fig. 1). This accelerating substitution of fuel vehicles by NEVs presents both formidable challenges and unprecedented opportunities for the gas station industry.

Concurrently, the number of electric vehicle charging piles has also grown at a breakneck pace, escalating from 1.681 million in 2020 to 8.596 million by the end of 2023 (Fig. 2). The growth rate of charging piles slightly outpaces that of electric vehicles, causing the vehicle-to-pile ratio to decline from 2.93:1 in 2020 to 2.37:1 by the end of 2023. This trend intensifies competition in the charging market. In tier-2 and higher cities, the clash between the burgeoning demand for charging infrastructure and the dwindling availability of prime land resources has driven up land prices and rental costs significantly. Coupled with the reduction in construction subsidies, newly-entered refined oil sales companies now face steeper cost pressures compared to charging pile operators who secured land and expanded prior to 2021.

• Types of Charging Stations for Refined Oil Sales Companies

Refined oil sales enterprises' electric vehicle projects are categorized into on-station and off-station charging initiatives. When integrating electric vehicle charging functions into gas stations, the latent land costs are borne by the gas stations. This process requires comprehensive consideration of factors such as site suitability, power supply availability, installation logistics, and transportation. Additionally, the integration must harmonize with station buildings and the surrounding environment without disrupting oil product operations, while meeting strict safety, environmental, economic, and maintenance standards.

For off-site charging projects, a thorough analysis of key determinants is essential, including project power connection costs, construction scale, equipment selection，construction expenditures, and station rentals, all tailored to diverse application scenarios. These projects, too, must adhere to stringent safety, environmental, economic, and maintenance requirements. Although on-site and off-site charging projects exhibit different cost structures, cost reduction and efficiency enhancement remain pivotal economic imperatives for both. Charging station construction necessitates adopting a low-cost development mindset and adhering to principles of prudent, targeted, and efficient investment.

This article offers a holistic approach, considering lease terms, on-site/off-site classifications, and site dimensions from three vantage points: layout design, facility selection, and construction techniques. It aims to guide refined oil sales companies in low-cost charging station construction, thereby alleviating the financial burdens associated with charging network development and operation (Table 1).

Optimization of Charging Station Layout Design for Refined Oil Sales Companies

• Layout principles

The master planning of charging stations must comply with current national, industry, and local regulations, standards, and legal frameworks. It should align with urban, regional, and road planning requirements. The layout should also consider customer consumption patterns and local infrastructure, maximizing land utilization through standardized design, vertical space optimization, and strategic use of marginal land. Grounded in commercial analysis, the layout should factor in usable area, charging station type, service model, and scale to create functional zones that efficiently meet customer needs.

• Cable layout

Cable configurations in charging stations can be divided into three segments: from the outdoor high-voltage connection point to the transformer, from the transformer to the charging piles, and between charging piles. The high-voltage T-connection to the transformer represents an external line, and it is advisable to locate this connection within 100 meters of the transformer. Distances exceeding this threshold require careful evaluation. The transformer and charging piles should be positioned in close proximity; halving the distance between them reduces cable engineering volume and associated investment by 50%.

There are two primary configurations for inter-pile cabling: single-side and central layouts (please refer to the figure below).

Assuming the width of the parking space is L, for the one-side layout, the cable length is:

For the intermediate arrangement, the cable lengths are:

Evidently, under identical site and parking space conditions, the central layout reduces cable length by 50% compared to the single-side layout. Therefore, the central layout is preferred, especially for large sites where cost savings are most pronounced. In stations with fewer charging spaces, where total cable requirements are minimal, layout decisions should prioritize coordination within station and compliance with safety regulations..

• Overall Facility Layout

Among the main facilities of the charging station, the positions of the high-voltage access point and the charging terminal are typically fixed, while the transformer and charging piles offer room for optimization. Contrary to intuition, placing the transformer midway between the high-voltage T-connection and charging piles is suboptimal. For example, in a 480 kW charging pile setup, laying cables from the T-connection to the transformer costs approximately CNY 510/m, and the cost of laying the line from the transformer to the charging pile is about CNY 1280/m, with a price difference of CNY 770 per meter. Thus, installing the transformer closer to the charging piles is recommended.

Similarly, charging piles should be sited as near as possible to the charging area. If the split charging host is close to the box-type transformer, the three DC low-voltage cables will be extended simultaneously. The more driving devices there are, the greater the cost disparity. Given that DC lines generally suffer higher power losses than AC lines, even if the transformer cannot be placed adjacent to parking spaces, charging piles should be positioned as close as feasible to minimize losses.

Optimization of Charging Station Facility Selection for Finished Oil Sales Enterprises

• Transformer, Charging Pile, and Charging Gun Configuration

To reduce transformer capacity upgrade costs, the transformer load rate needs to be moderately increased. It is recommended that the transformer load rate inside and outside the station be configured at 1:1, except for special requirements of the power supply bureau. For stations with over-capacity transformers, intelligent management systems such as "ordered charging controllers" must be configured in the charging master control cabinet to avoid the risk of current overload and reduce the impact on the transformer. Taking a 720 kW charging pile as an example, it is recommended to fully configure the terminal combination of 2 supercharging guns + 10 fast charging guns.

The power setting of the fast charging pile should be matched according to the main service models of the proposed station, and the power distribution ratio of the charging gun should be consistent with the proportion of different types of vehicles served. Taking the current stock of EVs and the models on the market as an example, 400V platforms dominate. During the charging process, the vehicle receiving power fluctuates between 40 kW and 70 kW. Factoring in the simultaneous use and power coefficients of charging guns and vehicles, an average charging gun power of 40-80 kW is recommended. For instance, a 480 kW air-cooled charging pile with 8 guns costs 25,200 yuan per gun, while a 10-gun configuration reduces this to 21,700 yuan—a 3,500 yuan per-parking-space saving. Thorough market research during project planning is crucial to avoid overprovisioning power and associated losses; a 50 kW average charging pile output is generally advisable.

• Cable material selection

Cables for charging stations come in copper-core and aluminum-core variants, with copper-core cables currently prevailing in applications ranging from gas stations and home wiring to charging piles and distribution equipment. Although aluminum-core cables cost approximately one-third of copper-core alternatives, they lag in several critical aspects:

• Higher Current-Carrying Capacity: Copper's lower resistivity enables copper-core cables to carry 30% more current than aluminum-core cables of the same cross-section.
• Enhanced Safety: Under identical current loads, copper-core cables generate less heat, reducing fire risks.
• Lower Energy Loss: Copper's superior conductivity minimizes power dissipation.
• Corrosion Resistance: Copper-core cable connectors resist oxidation, ensuring stable performance, whereas aluminum-core joints are prone to oxidation-induced failures.
• Ease of Installation: Copper's malleability and high mechanical strength simplify routing, bending, and connection processes.

For example, a 100-meter copper-core cable incurs 10kWh of power loss, while an aluminum-core cable at the same length loses 16.8kWh—1.68 times more. Over a year, copper-core cables require no maintenance, whereas aluminum-core cables necessitate an average of 8 repairs at CNY 2,000 each. Considering full life cycle costs, the total expenses for both types converge, making aluminum-core cables more suitable for short-term, temporary power setups. In summary, from the perspective of safety and full-life cycle cost, copper core cables should be used in charging stations.

• Station monitoring, lighting and fire protection

For in-station charging stations, reusing existing gas station cabinets and monitoring terminals is recommended, whereas out-station facilities require dedicated monitoring cabinets, terminals, and storage hard disks. Surveillance cameras should be positioned at corners, maintaining a safe distance from equipment to ensure comprehensive coverage. As a rule of thumb, 2 cameras per 10 parking spaces are adequate, with adjustments for irregularly-shaped sites. Footage should be stored for at least 30 days, or as mandated by local authorities..

Lighting systems should prioritize high-efficiency, energy-saving lamps that meet color rendering and startup time requirements, with illumination levels compliant with industry standards. In well-lit areas, relying on ambient light can reduce fixture counts; an internal lighting density of 1 lamp per 5 parking spaces is typical. Firefighting provisions should adhere to national and local regulations, proportional to station size and number of charging spaces. Repurposing idle firefighting equipment from decommissioned stations is encouraged. A standard setup includes 2 5 kg fire extinguishers per 2 charging terminals, complemented by emergency cut-off buttons and optional alarm systems.

Construction Technology Selection for Refined Oil Sales Companies' Charging Stations

• Charging shed setting

The setting of charging carports should be adapted to local conditions and divided into three types:

• No shed: Zero construction cost per parking space;
• Low-cost tensile membrane: 7,200 yuan per parking space;
• Photovoltaic-integrated light steel structure: Approximately 11,000 yuan per parking space. For cost-conscious projects, the first option is preferred.

• Charging station ground treatment

Five flooring types are available:

• Reusing existing parking surfaces;
• Grass brick flooring;
• 180mm lightweight hardened surfaces;
• 220mm standard hardened surfaces;
• Reinforced hardened surfaces. When constructing charging stations, reusing existing ground cover minimizes investment, reducing costs by 4,500 yuan per charging gun. If reuse is infeasible, the choice of flooring should match the station's service profile: grass bricks suit small vehicle-only stations; lightweight hardened surfaces suffice for sites with hardening requirements; standard surfaces accommodate medium and small vehicles; and reinforced surfaces are necessary for large vehicle parking and charging.

• Parking Space Coating and Protectio n

Parking space markings come in two forms:

• Outline-only painting (with optional numbering and charging signs), featuring a 150 mm-wide white border;
• Full-coverage PU anti-slip floor paint (ideal for high-visibility urban stations)..

Charging pile anti-collision columns should be vertical welded steel pipes, positioned to allow maintenance access. Installation heights should be 600 mm for small vehicles and 1000 mm for medium and large vehicles. Parking space blockers, also made of welded steel, should measure 2 m in length, 150 mm in height, and be coated with reflective warning paint.

• Cable laying method

Three cable laying techniques are commonly used:

• Direct burial: Armored cables are buried directly, with protective tubing only where crossing hardened surfaces or foundations;
• Ground cable trench: Cables are housed in trenches constructed on the existing floor;
• Rapid deployment: Surface-mounted cable tray systems enable quick installation and repositioning. For open sites requiring ground leveling and hardening, direct burial is most cost-effective. When reusing existing ground, cost comparisons should inform the choice between trench laying and rapid deployment methods.

Conclusion and Future Outlook

This article presents tailored solutions for low-cost construction of electric vehicle charging stations across diverse types, locations, and scales. By integrating layout design, facility selection, and construction techniques while complying with national standards and aesthetic considerations, it aims to support refined oil sales companies' charging business expansion.

Moving forward, these companies must prioritize high-quality station operations beyond construction. As the electric vehicle market evolves, user demands for charging services will diversify. Leveraging their existing resources, companies should strive to create a seamless "people, cars, life" ecosystem, offering convenient, comfortable experiences that elevate their competitive edge in the charging infrastructure landscape.