Designing and engineering electric vehicle (EV) charging stations is a complicated task. There are several different manufacturers and system components to ensure a safe and successful charging experience. Specifically for Direct Current Fast Charging (DCFC) stations, there are a few different ways an engineer can design the site based on desired charging performance, project budget, and available power capacity.
Ultimately, there are three types of DCFC site architectures: all-in-one, split system, and battery-integrated. Each has its advantages and disadvantages including equipment cost, charging performance, and installation complexity.
This article will break down the differences between the three DCFC site architecture designs and detail which one is best suited for certain situations.
All-In-One
An all-in-one DCFC, as the name implies, contains the power modules within the same unit as the charging dispenser. This type of DCFC is very space-efficient since it does not require a separate power cabinet for the power modules (steps up the grid power) and rectifiers (converts Alternating Current (AC) to Direct Current (DC)). Additionally, an all-in-one unit is typically cheaper than other DCFC types.
The downside of an all-in-one unit is that they are usually limited in power output. This can range from manufacturer to manufacturer, but generally, the maximum output is limited to around 25-240 kW. Another disadvantage is that power cannot be shared amongst a string of adjacent DCFCs to load manage or power optimize the site.
Popular models of all-in-one DCFCs are the ABB Terra series, Tritium PKM150, and the Autel MaxiCharger DC Fast. Prices for all-in-one DCFCs start around $50,000.
Advantages:
- Lower cost
- Minimal station footprint
Disadvantages:
- Limited power output
- Inefficient use of power
- Decreased vehicle throughput
Ideal Locations:
- Grocery stores
- Medium-duty (bus, van, box truck) fleet depot
- Urban parking garages
Split System
Unlike an all-in-one DCFC, a split system, sometimes called a distributed system, includes a separate power cabinet and charging dispenser. While this site architecture uses more space and costs more than an all-in-one, it is better suited for sites that require high charging performance as well as the ability to optimize available power across several chargers via load management. Generally, a single power cabinet can be connected to up to four charging dispensers. Power can be modulated via a load management system to each of the four connected charging dispensers so as not to overload the power cabinet and/or switchgear. With a split system DCFC architecture, site hosts can ensure that EVs are receiving as much power as delivered to the site regardless of where they plug in.
Furthermore, because the power cabinets are abled to be sized to the needs of the site, they can provide more power output than a typical all-in-one DCFC. As a result, many power cabinets can output 600 kW across multiple dispensers. Even more, some manufacturers have engineered their power cabinets to be linked together to spread power even more efficiently. Altogether, split system DCFCs are capable of delivering over 350 kW per dispenser, which is currently the highest power output for light-duty EVs.
A split system DCFC is very popular for new installations, especially for highway reststops or commercial locations. Notable split system DCFC models include the Chargepoint Express Plus, BTC Gen4 Split System, and the Kempower Distributed DCFC. Prices for split system DCFCs start around $80,000.
Advantages:
- High power output
- Increase vehicle throughput
- Efficient use of power
Disadvantages:
- High cost
- Large station footprint
Battery-Integrated
Lastly, the battery-integrated DCFC solves a specific problem that can be an issue for DCFC site hosts. Electric utility providers charge demand fees for customers that exceed a certain threshold of power at any given time during a billing cycle. For DCFC sites, this can easily amount to hundreds or thousands of dollars per month depending on the amount of power pulled at any given time. Even if a charging station pulled 350 kW just for one minute in one month, the site host will be billed demand fees for that power increment.
To avoid these demand fees, a battery can be used as a median between the utility connection and the charging dispenser. By slowing charging the battery, the site host can avoid the demand fees. When a charging session occurs, the battery and charging equipment can ramp up power to supply the requested electricity to the EV. Another advantage to this type of DCFC is that because the grid connection is relatively minimal, they can often be installed at sites without the need for electrical service upgrades. This alone can save tens of thousands of dollars.
While the battery can be installed as a separate unit from the DCFC, it can also be integrated into the DCFC. A battery-integrated DCFC takes the approach of an all-in-one DCFC and enlarges the footprint to include a battery. While a battery-integrated DCFC avoids demand fees, it does require more space than a conventional all-in-one DCFC (but less than a split system DCFC).
Additionally, of the three different types of DCFCS, they are the most expensive. This is due to the large battery pack within the charging unit. Another disadvantage of a battery-integrated DCFC is that once that battery is fully discharged, the DCFC is only able to charge EVs at its grid connection power level, which is typically around 30 kW. Manufacturers claim these types of DCFCs can charge up to 20 EVs per day.
The battery packs of battery-integrated DCFCs range from 160 kWh to as much as 466 kWh. As far as output, battery-integrated DCFCs can provide around 200 kW to an EV. Popular models include the Freewire Boost 200 and the XCharge Net Zero Series. Prices for batter-integrated DCFCs start around $170,000.
Advantages:
- Avoids utility demand fees
- Small station footprint
- Avoids electrical service upgrades
Disadvantages:
- Most expensive
- Minimal charging performance once the integrated battery is fully discharged
Closing Thoughts
Are you interested in getting EV chargers installed at your property? Contact us today to learn how we can help. We’ll help you navigate the project from start to finish.
Hi there! I’m the founder and project manager at Charged Future: the EV charging consultancy. Charged Future helps businesses achieve their EV charging goals. Specifically, I serve as the project manager for your EV charging project, which can save you both time and money! Additionally, I can search and apply to all eligible rebate applications, which can typically cover a large portion of the project cost.
