Investing in EV Charging Station: Choosing Between Charging Stacks and All-in-one Charging Pile?
Many operators have been hesitant about choosing equipment for building charging stations. As two different forms of electric vehicle charging facilities, charging stacks and charging piles each serve different technical purposes and application scenarios. Although they are often misunderstood as the same concept, they differ greatly in design, functional applications, advantages and disadvantages. Maruikel has sorted out and summarized these differences to help operators select charging equipment that suits them.
Definitions of Charging Piles and Charging Stacks
1. Charging piles
New energy vehicle charging piles are like "gas stations" for electric vehicles, but they provide electrical power rather than gasoline.
It is usually installed in public buildings, parking lots, shopping malls, charging stations for operating vehicles, and private places such as residential communities. Charging piles can be classified into AC charging piles and DC charging piles according to the charging type. AC charging piles have a small charging current and a long charging time (usually 7 - 10 hours), which is slow charging and suitable for parking spaces in residential areas and office buildings. DC charging piles are mainly used for public charging. They convert AC power into DC power, have a short charging time (one to two hours), which is fast charging, and are suitable for public places where fast charging is required.
2. Charging Stacks
A charging stack is a large - scale power source cluster specifically designed to meet large - scale charging demands, such as in large parking lots or enterprises. The charging stack can convert AC power into DC power and is equipped with multiple charging modules that can serve multiple electric vehicles simultaneously. Its design aims to efficiently utilize power modules and rationally allocate charging power, meeting the charging needs of different vehicle models, and improving charging conversion efficiency and equipment utilization.
Composition Structures of Charging Piles and Charging Stacks
1. Charging Piles
(1) Power supply: The charging pile needs to be connected to a power source to provide electricity. The power source can come from the power grid or green energy devices such as solar panels.
(2) Control panel: The control panel is the core part of the charging pile. It can realize the control and monitoring of the charging pile, including power calculation, automatic stop, charging speed control, etc.
(3) Charging interface: The charging interface is the connector between the charging pile and the electric vehicle, through which information exchange and power transmission can be carried out. There are two types of charging interfaces: DC fast - charging and AC slow – charging.
(4) Protection barrier: The protection barrier is a physical safety device that can protect the charging pile and charging equipment from the impact of the external environment, such as bad weather and moisture!
(5) Housing: The housing is the external packaging of the charging pile. It can protect the internal equipment of the charging pile from damage by the external environment and also plays a role in aesthetics and decoration.
(6) Support frame: The support frame is a device used to support the charging interface. It is usually fixed on the charging pile and can adjust the height and angle of the charging interface to adapt to different models of vehicles.
2. Charging Stacks
(1) Energy unit: This is the basic part of the charging stack, responsible for converting AC power into DC power for electric vehicle charging.
(2) Charging controller: Controls all aspects of the charging process to ensure the safety and efficiency of charging.
(3) Monitoring system: Monitors parameters such as battery voltage, current, and temperature in real - time during the charging process to ensure charging safety.
(4) Energy scheduling system: Manages the overall energy flow of the charging stack and optimizes charging efficiency.
(5) Communication system: Connects the charging stack to the cloud server to achieve remote monitoring and management, improving the intelligence and digitization level of the charging stack.
(6) Cooling system: Maintains the normal internal temperature of the charging stack to prevent overheating from affecting charging efficiency and equipment lifespan.
Working Principles of Charging Piles and Charging Stacks
1. Charging Pile
The working principle of the charging pile mainly involves two aspects: power conversion and transmission.
(1) Power conversion: The core part of the charging pile is a converter that converts grid power into DC power. The converter converts the AC power of the grid into DC power, which is then transmitted to the battery of the electric vehicle through the charging cable.
(2) Transmission method: There are two main methods of power transmission: wired transmission and wireless transmission. Wired transmission is to transmit grid power to the battery of the electric vehicle through a cable; wireless transmission is to transmit power to the battery of the electric vehicle through a magnetic field. At present, wireless transmission technology is still in the research and development stage and has not yet been widely applied.
2. Charging Stack
The charging stack is mainly composed of a charging module, a monitoring module, an energy scheduling module, and a communication module. These modules cooperate with each other to complete the intelligent charging task. The monitoring module monitors parameters such as the voltage, current, and temperature of the battery module in real - time, and adjusts the output of the charging module according to these parameters to ensure safe charging according to the needs of the battery module at the vehicle end. The communication module is connected to the cloud server to achieve remote monitoring and management, improving the intelligence and digitization of the charging stack.
The charging module is the core component of the DC charging equipment for electric vehicles. Its main function is to convert the AC power in the power grid into DC power for battery charging. It is also the most valuable part of the charging pile industry, accounting for about 50% of the cost of the entire charging pile.
Application Scenarios of Charging Piles and Charging Stacks
1. Charging Piles
Public places:
As one of the main application scenarios of charging piles, public places such as parking lots, gas stations, and shopping malls have a large flow of people and vehicles, resulting in a high demand for electric vehicle charging. Installing charging piles in public places can not only meet the charging needs of electric vehicle users but also make a positive contribution to the sustainable development of the city.
Residential areas:
Residential areas such as communities, apartments, and villas. Installing charging piles in these residential areas can not only provide great convenience for residents, allowing them to easily charge their electric vehicles, but also significantly improve the quality of life of residents. By deploying charging piles in residential areas, residents can avoid traveling long distances to find public charging stations, thus saving time and energy. In addition, this convenience can also encourage more residents to choose electric vehicles as their daily means of mobility, thus promoting environmentally friendly travel and reducing carbon emissions.
Office and production areas:
Places like government buildings, companies, factories, hospitals, and schools also need charging piles because there are many people and EVs. Installing charging piles in these places can not only facilitate employees or users to charge their electric vehicles but also help meet their needs for commuting to and from work or for official business, office work, and production.
2. Charging Stacks
Highways, ports and airports etc. with dense and fast population flow: Charging piles can provide fast charging services for electric vehicles, alleviating the range anxiety of electric vehicles, e.g. a 5 - minute charge can enable the vehicle to travel 200 kilometers.
Commercial areas: Charging piles can give full play to the role of smart charging in online car-hailing and public charging around cities. The charging speed can be fast or slow, and users can choose based on their actual needs.
Other application scenarios: Charging piles can also be used in commercial areas, residential areas, etc., and small power stacks can be used to achieve wheel charging, orderly charging, etc., and can also be combined with energy storage to achieve an integrated PV-storage-charging system.
Both charging piles and charging stacks are charging facilities for electric vehicles. There will inevitably be some overlaps in their application scenarios, but generally, charging piles are suitable for individual users or small-scale locations, while charging stacks are more likely to be applied in areas with large-scale charging demand such as large parking lots and highway service areas.
Pros and Cons of Charging Piles and Charging Stacks
1. Charging piles
(1) Advantages:
Easy to use: Charging piles take into account the needs of many individual users, so the installation and use of charging piles are relatively simple and can meet basic charging needs. However, the installation process involves electrical safety, power supply access, grounding connection and other operations. It is recommended to find personnel with professional knowledge and experience to operate.
Low cost: Compared with charging piles, the R&D and production costs of charging piles are lower. These factors lead to a relatively low unit price of charging piles, which is more suitable for installation in parking lots, residential areas and other places.
(2) Disadvantages:
Poor compatibility: The power of charging piles is fixed and cannot meet the charging needs of different vehicle models. When a vehicle with low power demand is connected to a high-power charging pile, it will lead to unnecessary waste of electric energy; conversely, when a high-power vehicle is charged at a low-power charging pile, it cannot fully realize its fast charging potential and the charging time will be significantly extended. This "one-size-fits-all" charging solution limits the wide applicability and user experience of charging piles.
Poor adaptability: With the rapid development of battery technology, electric vehicles are moving towards a high-voltage platform. Nevertheless, since the power of charging piles is fixed, to meet the charging needs of future electric vehicles, it is only possible to reinvest and replace the entire pile.
Low efficiency: Compared with charging stacks, charging piles have a certain gap in charging efficiency. This is mainly because charging stacks usually adopt more advanced charging technology and optimization algorithms, which can more efficiently manage the distribution and transmission of electric energy and reduce energy loss. Due to limitations in design and configuration, charging piles often cannot achieve the same high-efficiency charging level as charging stacks.
2. Charging Stacks
(1) Advantages:
Diverse charging demands: When a charging station needs to provide charging services for multiple different models of electric vehicles at the same time, the charging stack can adapt to various charging needs because it is equipped with charging heads of various specifications without the need to replace or add additional equipment.
High efficiency and fast charging: The charging stack employs efficient charging technology to charge electric vehicles quickly and safely, improving charging efficiency. Especially when electric vehicles are in urgent need of fast charging, the high efficiency of the charging pile can meet this demand.
Modular design: The modular design of the charging pile makes its composition flexible, and battery cells can be added or reduced according to actual needs to adjust the amount of energy storage. This design makes the charging pile more convenient and economical when expanding and upgrading.
Small footprint: In urban centers or areas with limited space, the modular design of the charging pile enables the construction of charging stations in relatively small spaces, making full use of land resources.
Multi-channel simultaneous charging: The charging stack can support multiple - way simultaneous charging for different vehicle models, improving the utilization rate and service efficiency of the charging station. In contrast, the integrated charging pile may only provide charging services for a single vehicle model, limiting its scope of use.
Intelligent adjustment: The charging stack can realize intelligent adjustment of the output power of each terminal to meet the charging needs of different vehicle models. This intelligent adjustment function can improve charging efficiency and reduce energy consumption.
(2) Disadvantages:
High cost: The manufacturing cost of the charging pile is higher than that of an integrated charging pile. First, the cable cost is high. The charging pile uses DC power distribution, and the cable used must be thick to consider the charging adaptability of the charging pile. Second, the equipment cost of the charging pile itself is high.
Inconvenient maintenance: If the charging stack fails, all the charging guns cannot be used, so the parking space would not be able to work normally. The charging stack has a higher failure rate and is less mature and stable than the integrated machine.
Although the standards such as the charging pile interface have been unified, the problem of "upward compatibility" has not been effectively solved. With the continuous advancement of battery technology, the demand of charging facilities for new energy vehicles will continue to increase. Whether the charging piles built now are suitable for future new energy vehicles has also become a major issue faced by the industry.
The charging stack does not need to consider issues such as charging rate and battery capacity during charging. It can automatically match the charging power according to the power required by the battery. In the future, when the battery energy density increases and the battery capacity increases, the charging stack can still be upgraded by replacing the charging module with a higher power, thus effectively solving the problem of "upward compatibility" of charging piles.
Construction Costs of Charging Piles and Charging Stacks
The construction costs of charging piles and charging stacks are affected by many factors, including equipment type, power, brand, geographical location, policy subsidies, etc. The following are some cost estimates:
1. Charging pile construction cost:
For a single charging pile, taking a 60KW single pile as an example, the equipment cost is about US$18,000 (about US$2/W). The overall investment and construction cost, including power, land, and infrastructure construction, is about $40,714 - $64,571 per station.
For building a charging station, if a 120KW DC dual-gun charging pile is selected, the price is about US$34,562 (about US$2/W), and for 10 units, it is US$2.4 million; it needs to match a 1,250kVA power system, the cost of the power distribution system (the specific amount needs to be determined according to the actual situation, but the following is only a simplified example). If it is necessary to re-apply for construction, the power plus infrastructure cost is about US$93,024, and the overall investment and construction cost is about US$1,277,760. The cost of civil construction, including site hardening, building canopies, etc., will vary according to the actual situation.
Site rental, the cost will vary depending on the number of parking spaces required and the geographical location.
2. Charging stack construction cost:
The cost of the charging stack varies according to the number and power of the charging modules equipped. For example, the price of a 360kW charging pile is about US$53,800 (The cable configuration of the charging stack is different from that of the charging pile, which may lead to cost differences. The construction cost of the charging pile may be slightly higher due to the need for more complex power facilities and construction costs.
3. Other costs
The construction of the charging station also needs to consider other costs such as transformers, charging monitoring systems, safety monitoring, charging metering and billing systems.
Operating costs include staff expenses, maintenance expenses, electricity costs, etc.
4. Policy subsidies
Germany:
High-power piles above 100KW could enjoy a subsidy of up to 30,000 euros.
The maximum subsidy for AC public piles is 2,500 euros.
Private piles can receive a subsidy of 900 euros.
Italy: Up to 50% (up to 2,000 euros) of the total cost of purchasing and installing an electric vehicle charging station of up to 220 KW in private parking spaces (individual or shared) can be refunded.
5. Deployment Strategy
The construction cost of the charging piles is relatively low, suitable for small-scale deployment; while the construction cost of the charging stacks may be slightly higher, but due to its modular and power-sharing characteristics, it is suitable for large-scale, high-efficiency charging demands.
How to Choose the Appropriate Charging Pile or Charging Stack
When choosing charging piles and charging stacks, multiple factors need to be considered to ensure they are suitable for relevant vehicles and usage scenarios.
1. Confirm Technical Specifications:
Output power: Ensure that the charging pile can provide stable power output to meet the vehicle's fast - charging needs. For example, a 60~120kw DC charging pile or a 7~21kw AC charging pile is normally used for a small household car. For large vehicles that need fast charging, a 60 - 180 - kW DC charging pile or even a charging pile with a larger output power can be selected.
Voltage and current range: Check the voltage and current range supported by the charging pile to ensure compatibility with electric vehicles.
Charging interface standard: Select interfaces that comply with international or regional standards, such as CCS, CHAdeMO or GB/T, to ensure wide compatibility. It is also necessary to confirm whether the vehicle supports DC/AC charging.
Charging efficiency: Pay attention to the conversion efficiency of the charging pile to reduce energy loss and optimize operating costs.
2. Confirm Functional Features
Intelligent management: Select charging piles that support remote monitoring and management functions to facilitate equipment status monitoring and fault diagnosis.
User interface: An intuitive and easy-to-use user interface that supports multiple payment methods could lead to higher consumer satisfaction.
Safety features: Ensure that the charging pile has multiple safety protection measures such as overvoltage, overcurrent, and short-circuit protection.
Network connection: Support Wi-Fi, Ethernet or 4G connection to facilitate software updates and data transmission.
3. Confirm Application Scenarios
Target users: Clarify the main service targets to select the appropriate product specification.
Installation environment: Consider the impact of the space, power supply capacity and environmental conditions of the installation site on the performance of the equipment.
Future expansion: Evaluate the possibility of adding more charging piles and choose a system architecture that supports expansion
Power sharing: The charging stack can centralize power, and each charging terminal can obtain the required power from this power stack. According to the actual situation, users need to calculate to determine the capacity of the charging stack and the number of terminals to be matched.
Flexible charging: Based on the charging demand issued by the vehicle Battery Management System (BMS), the charging power is allocated on demand. The charging stack allocates power on demand, which can achieve the maximum charging speed of the vehicle. However, when there are many vehicles, if the total charging power exceeds the rated power, the power will be rationally allocated for shared use.
Smooth expansion: With the increase in battery charging rate and the growing demand for charging power, the power of the power stack can be expanded to meet the charging demand.
Energy saving and high efficiency: Regardless of the charging demand, the charging equipment should be ensured to work within the optimal load rate range.
Adaptability: The charging stack can meet the different power requirements of various models for charging, and improve the charging conversion efficiency and equipment utilization of charging facilities.
Compatibility: The charging stack can tackle the challenge of "upward compatibility" of charging piles and adapt to the rapid development of battery technology.
When choosing charging piles and charging stacks, factors such as safety, cost, convenience and charging speed should also be considered. Be sure to select charging equipment that conforms to national standards and have it installed and maintained by professionals to ensure the safety and efficiency of the charging process.
