What is Load Balancing and Why Your Charging Site Needs It

What is Load Balancing and Why Your Charging Site Needs It

A commercial site with four 150 kW DC fast chargers theoretically requires 600 kW of electrical capacity. In practice, the site rarely needs that much power because not all vehicles charge at maximum power at the same time, and many vehicles reduce their charging rate as batteries fill. Load balancing is the technology that takes advantage of this behavior to serve more vehicles with less electrical infrastructure. Without it, operators either overspend on utility upgrades or limit the number of chargers they can install. This article explains how load balancing works, the difference between static and dynamic approaches, and how to implement it effectively.

The Power Problem at Charging Sites

Electrical infrastructure is often the most expensive and time-consuming part of a charging project. Utility service upgrades can take 12 to 18 months and cost hundreds of thousands of dollars. Demand charges—utility fees based on the highest power draw during a billing period—can represent 30% to 50% of total electricity costs.

A naive approach would size the electrical service for the sum of all charger nameplate ratings. A site with six 150 kW chargers would request 900 kW of service. But real-world charging behavior rarely reaches this peak simultaneously. Load balancing allows the site to operate safely with a smaller grid connection by distributing available power intelligently among active chargers.

Why Grid Capacity Became the Bottleneck

The transition to electric mobility is pushing commercial electricity demand to levels many buildings were never designed to handle. A typical Class 8 electric truck can require 300–600 kWh of energy per shift. A single 350 kW DC fast charger draws more power than a small office building. When multiple chargers are installed at a gas station, fleet depot, or logistics hub, the cumulative load can exceed the available transformer capacity, service entrance rating, or utility feeder limits.

Grid interconnection studies, transformer upgrades, and new switchgear add both cost and schedule risk. In dense urban areas or older industrial parks, the local distribution network may not have spare capacity at any price. Load balancing does not eliminate the need for a safe electrical design, but it can defer or avoid a full utility upgrade by ensuring that the site never draws more than its allocated limit, even when every charger is occupied.

The Cost of Oversizing

Oversizing electrical service to match nameplate charger ratings has three direct consequences:

• Higher capital expense: Larger transformers, switchgear, conductors, and conduits increase installation costs.
• Longer permitting and construction timelines: Utility coordination for large service upgrades often extends project schedules by six to twelve months.
• Higher fixed demand charges: A utility service sized for 900 kW may trigger demand tariffs that apply even when the site only uses a fraction of that capacity.

Load balancing converts the site from a deterministic design—where peak load equals the sum of all chargers—into a probabilistic design based on actual vehicle behavior. This shift is what makes commercial EV charging financially viable at scale.

What Is Load Balancing?

Load balancing for EV charging is the real-time management of electrical power across multiple charging points. Instead of each charger drawing its maximum rated power independently, a central controller allocates power based on:

• Total available site capacity
• Number of vehicles currently charging
• Each vehicle's requested power and battery state of charge
• Operator-defined priorities and pricing rules
• Time-of-use electricity rates

The goal is to maximize charger utilization and vehicle throughput while staying within the site's electrical constraints and minimizing demand charges.

The Control Loop

At the heart of load balancing is a continuous control loop:

1. Sense: Meters measure site-level power draw, individual charger output, and grid import.
2. Predict: The system estimates how power needs will evolve over the next few minutes based on plugged-in vehicles, dwell times, and scheduled departures.
3. Decide: An optimization engine calculates the best power allocation for each charger subject to site limits, vehicle limits, and business rules.
4. Command: The controller sends power limits or charging profiles to each charger.
5. Verify: The system checks that actual power draw matches the target and adjusts if grid conditions or vehicle behavior change.

Modern systems run this loop every one to ten seconds. Cloud-based platforms can coordinate across multiple sites, while edge controllers provide sub-second response for sites with tight demand limits or on-site generation.

Static Load Balancing: Fixed Allocation

Static load balancing assigns a fixed maximum power limit to each charger. For example, a site with 300 kW of available capacity and six 50 kW chargers might limit each charger to 50 kW permanently. This is simple but inflexible.

Advantages

• Simple to design and commission
• Predictable power demand
• No complex software required

Disadvantages

• Wastes capacity when fewer vehicles are charging
• Cannot adapt to peak demand periods
• May under-serve vehicles capable of faster charging

Static load balancing is appropriate for small sites with predictable usage and limited budget for advanced controls. However, it leaves money on the table by not maximizing the value of the electrical service.

When Static Allocation Still Makes Sense

Despite its limitations, static load balancing remains a valid choice in specific cases:

• Small workplace installations with a known number of employee vehicles and long dwell times.
• Residential condominiums where each parking space receives a dedicated circuit and fairness matters more than speed.
• Pilot projects that need to prove utilization before investing in dynamic controls.
• Sites with extremely tight and stable grid limits where the cost of advanced controls cannot be justified.

For these applications, FBK POWER's Wall-Mounted AC Charging Station and Pedestal AC Charging support simple fixed-current allocation through their onboard controllers, making static deployment straightforward.

Dynamic Load Balancing: Real-Time Power Distribution

Dynamic load balancing continuously adjusts power allocation based on actual demand. If only one vehicle is plugged in, it can use nearly the full site capacity. When a second vehicle arrives, power is shared. When vehicles taper their charging rate, the freed capacity is redirected to other vehicles.

How It Works

1. A site energy meter measures total power consumption
2. The load management system calculates available headroom below the site limit
3. Each charger reports vehicle demand and state
4. The controller allocates power to maximize total throughput
5. Allocations update every few seconds as conditions change

Advantages

• Maximizes utilization of existing electrical capacity
• Reduces need for costly utility upgrades
• Lowers demand charges by smoothing peak power
• Improves customer experience with faster average charging
• Supports more chargers per site

Disadvantages

• Requires intelligent chargers and a central controller
• More complex design and commissioning
• Needs ongoing monitoring and tuning

For most commercial deployments, dynamic load balancing is the preferred approach because it delivers better economics and better user experience.

Dynamic Algorithms in Plain Language

Several algorithms can be used inside a dynamic load balancing system:

Most real-world systems combine two or more of these rules. A public charging hub might use equal sharing by default but boost power for a vehicle with very low battery when capacity becomes available.

Load Balancing vs. Load Management

The terms are sometimes used interchangeably, but they have distinct meanings:

A comprehensive charging management strategy may use all of these techniques together.

Dynamic Load Balancing in Practice

Consider a fleet depot with 400 kW of available grid capacity and four 150 kW DC fast chargers. The total nameplate rating is 600 kW, but the site is limited to 400 kW.

Scenario 1: One Vehicle Charging

A single electric truck plugs in with a low battery and requests 150 kW. The load management system allocates 150 kW. The remaining 250 kW of site capacity is available but unused.

Scenario 2: Two Vehicles Charging

A second truck plugs in and requests 150 kW. The system now has 300 kW of demand against 400 kW of capacity. Both vehicles receive 150 kW.

Scenario 3: Three Vehicles Charging

A third truck arrives. Total demand is 450 kW, but the site limit is 400 kW. The system reduces each vehicle to 133 kW. All three vehicles still charge, but more slowly than if they were alone.

Scenario 4: Tapering and Redistribution

As the first truck's battery fills, its demand drops to 80 kW. The system redistributes the freed 70 kW to the other two vehicles, which now receive more power. Total site demand stays near 400 kW, and throughput is maximized.

Scenario 5: Adding Energy Storage

If the same depot installs a 200 kW / 400 kWh battery energy storage system, the effective site capacity during a peak event rises to 600 kW. When three trucks demand 450 kW, the battery supplements the grid with 50 kW, allowing all three trucks to charge at 150 kW. The battery then recharges at night when grid demand and electricity prices are lower.

This scenario is where FBK POWER's All-in-One Battery System and Split-Type DC Charging Cabinet combine to create a high-throughput depot without a full utility upgrade.

Demand Charge Reduction

Utilities typically bill commercial customers based on both energy consumption (kWh) and peak power demand (kW). Demand charges are calculated from the highest 15-minute average power draw during the billing period. A single high-power charging event can set the demand charge for the entire month.

Load balancing helps reduce demand charges by:

• Preventing simultaneous peak draws from multiple chargers
• Smoothing power consumption over time
• Coordinating with energy storage to discharge during peak events
• Scheduling non-essential charging during off-peak hours

For a site with multiple 150 kW chargers, effective load management can reduce monthly demand charges by thousands of dollars.

A Real Demand Charge Example

Assume a commercial site has a demand charge of $25 per kW per month. Without load balancing, three chargers pulling 150 kW simultaneously create a 450 kW peak. The monthly demand charge is:

450 kW × $25/kW = $11,250

With dynamic load balancing, the same three chargers are capped at a combined 300 kW during the highest-demand interval. The monthly demand charge becomes:

300 kW × $25/kW = $7,500

That single control strategy saves $3,750 per month, or $45,000 per year. In regions with higher demand charges or ratchet clauses, the savings can be substantially larger.

Load Balancing for Different Site Types

Workplace Charging

Workplace chargers often operate for 6 to 10 hours per day. Vehicles arrive at different times and have varying battery levels. Dynamic load balancing allows a large number of Level 2 chargers to share limited panel capacity, maximizing the number of employees who can charge without a major electrical upgrade.

Fleet Depots

Fleet depots have predictable schedules but high power demand. Load balancing ensures that all vehicles receive enough charge overnight while keeping total demand within utility limits. Integration with fleet management software allows charging to align with route schedules and vehicle availability. For logistics and heavy-duty fleet deployments, see FBK POWER's logistics solutions.

Public Charging Hubs

Public hubs experience unpredictable arrival patterns. Dynamic load balancing maximizes revenue by serving as many vehicles as possible with the available infrastructure. It also prevents the site from tripping breakers during peak periods. Gas stations converting fuel pumps to charging bays are a prime example; FBK POWER's gas station solutions describe how modular cabinets and load management work together in this environment.

Multi-Unit Residential Buildings

Apartment and condo buildings often have limited electrical capacity. Load balancing allows shared charging stations to operate within the building's existing service, avoiding expensive transformer upgrades.

Public Transport Depots

Electric bus depots face unique load balancing requirements. Buses return to the depot at the end of service and must be fully charged before the morning route. A depot with 50 buses and 100 kW chargers per bus would require 5 MW if all buses charged simultaneously. In practice, staged charging windows and dynamic allocation allow the depot to operate with 2–3 MW of grid capacity. See FBK POWER's public transport solutions for heavy-duty depot designs.

Load Balancing and Energy Storage

Battery energy storage systems (BESS) enhance load balancing by absorbing excess power during low-demand periods and discharging during high-demand periods. This combination enables:

• Peak shaving: Reduce maximum grid demand
• Demand response: Participate in utility programs that pay for load reduction
• Renewable integration: Store solar generation for use during charging peaks
• Backup power: Maintain limited charging during grid outages

FBK POWER's all-in-one battery systems can be integrated with charging sites to provide these capabilities. When paired with smart load management, the system optimizes both charging economics and grid impact.

Solar-Plus-Storage Load Balancing

When solar panels are added to a charging site, the available grid capacity effectively increases during sunny hours. A 200 kW solar array can offset 200 kW of charger load at midday. The load balancing controller must account for solar variability: if a cloud reduces solar output by 50 kW, the system must either reduce charger power or draw from the battery to maintain the site limit.

FBK POWER's 540W monocrystalline solar panels and All-in-One Battery System are designed to work as a unified energy ecosystem with the site's chargers and load manager.

Portable Power for Emergency Backup

For mobile or temporary load balancing needs, portable power stations provide a flexible source of AC or DC power. During a grid outage or maintenance event, a T30-3000W Portable Power Station can maintain critical chargers or keep site control systems online until grid service is restored.

How OCPP Enables Load Balancing

The Open Charge Point Protocol (OCPP) includes messages for smart charging and load management. A central system can send charging profiles to individual chargers, specifying maximum power limits based on real-time conditions. OCPP 1.6 supports basic smart charging, while OCPP 2.0.1 adds more advanced features for dynamic power distribution and security.

FBK POWER chargers support OCPP 1.6 and can receive smart charging profiles from central management systems. This allows integration with third-party energy management platforms or FBK POWER's own backend for sites that require a turnkey solution.

Charging Profiles Explained

OCPP smart charging uses three types of charging profiles:

By combining these profiles, a central system can enforce site-level limits while still giving individual vehicles the power they need. FBK POWER's chargers implement these profiles consistently, which simplifies integration with OCPP-compliant energy management systems.

Standards and Regulations Relevant to Load Balancing

Load balancing is not only a software feature; it must be implemented within electrical, safety, and communication standards. Key references include:

• IEC 61851-1: General requirements for EV conductive charging systems, including control pilot signaling that can limit AC charging current.
• ISO 15118: Defines vehicle-to-infrastructure communication, including high-level charging schedules that can support grid-friendly load management.
• OCPP 1.6 and 2.0.1: The dominant open protocols for charger-to-backend communication and smart charging profiles.
• UL 2594 and UL 2251: Safety standards for EV supply equipment and couplers used in North America.
• IEEE 1547: Interconnection standards for distributed energy resources, including solar and storage integrated with charging sites.

FBK POWER designs its products to comply with these standards. More details are available on the certifications and standards pages.

Matching Load Balancing to FBK POWER Products

Different site types benefit from different FBK POWER hardware combinations:

This mapping helps operators choose hardware that supports their load balancing strategy rather than treating chargers and power management as separate decisions.

Designing a Load-Balanced Charging Site

Effective load balancing starts during site design. Key steps include:

1. Estimate total demand: Calculate the likely simultaneous charging load based on vehicle types and dwell times
2. Define site limits: Determine the maximum power available from the grid or on-site generation
3. Select controllable chargers: Ensure chargers support load management commands via OCPP or proprietary protocols
4. Choose a load management platform: Use a central controller that can monitor site power and issue commands
5. Set rules and priorities: Define how power should be allocated during congestion
6. Monitor and optimize: Track actual usage and adjust settings over time

Pre-Deployment Checklist

Before commissioning a load-balanced site, verify the following:

• [ ] Site maximum demand limit is documented and programmed into the controller
• [ ] Each charger supports the required communication protocol and charging profile types
• [ ] Meters are installed at the utility service entrance and at major sub-panels
• [ ] Energy storage, if used, is integrated into the load management loop
• [ ] Solar forecasting or real-time solar production data is available to the controller
• [ ] Fail-safe behavior is defined for communication loss or meter failure
• [ ] Driver-facing displays or apps communicate expected charging power and duration
• [ ] Utility demand charge tariffs are modeled in the optimization objective
• [ ] Cybersecurity policies cover charger credentials, certificates, and backend access
• [ ] Maintenance staff are trained on alarm response and profile updates

A site that completes this checklist is far more likely to achieve both economic targets and reliable operation.

Decision Framework: Static or Dynamic?

Choosing between static and dynamic load balancing depends on site characteristics and business goals. Use the following framework:

If more than four factors point to dynamic load balancing, the additional investment in controls will usually pay back within the first year through demand charge savings and higher charger utilization.

Common Load Balancing Mistakes

Undersizing Electrical Service

Load balancing can stretch capacity, but it cannot create power that does not exist. If the site limit is too low, vehicles will charge slowly and customer satisfaction will suffer.

Ignoring Demand Charges

Focusing only on energy costs while ignoring demand charges can lead to unexpectedly high electricity bills. Load balancing should be designed to manage both.

Poor Communication Between Chargers

Load balancing only works if chargers can receive and respond to commands in real time. Using non-networked or proprietary chargers without load management support limits flexibility.

Static Allocation for Dynamic Sites

Applying static limits to sites with variable usage wastes capacity and reduces revenue. Dynamic load balancing is usually worth the additional investment for commercial sites.

Setting and Forgetting

Even a well-tuned load management system needs periodic review. Vehicle mix changes, electricity rates evolve, and new chargers are added. Quarterly reviews of power profiles and demand charge bills help capture ongoing savings.

Load Balancing and the User Experience

While load balancing is primarily an operational technology, it also affects drivers. Clear communication about expected charging power and time helps set expectations. Mobile apps and station displays can show drivers how power is being shared and when their session will complete.

Well-designed load balancing should be invisible to most users. Vehicles charge as fast as possible given site conditions, and drivers see consistent, reliable service.

What to Show Drivers

Transparency improves satisfaction. Consider displaying:

• Current charging power
• Estimated time to target state of charge
• Explanation if power is reduced due to high site demand
• Pricing that reflects time-of-use or demand-based rates

When drivers understand why charging speeds vary, they are less likely to blame the charger or the operator for conditions outside anyone's control.

Future Trends in Load Balancing

Artificial Intelligence and Predictive Control

Machine learning models can predict arrival times, battery states, and dwell durations based on historical patterns. Predictive load balancing pre-positions power before a vehicle plugs in, reducing the response lag that occurs with purely reactive systems.

Vehicle-to-Grid and Bidirectional Load Management

As V2G-capable vehicles become common, load balancing will expand to include bidirectional power flows. Vehicles will not only receive power when the grid has capacity but may also discharge to support the site during peak events, creating a new layer of flexibility.

Megawatt Charging for Heavy Duty

The Megawatt Charging System (MCS) under development for electric trucks will push single-vehicle demand above 1 MW. Load balancing at MCS depots will require sub-second coordination across multiple megawatt-class chargers, energy storage, and on-site generation.

Key Takeaways for Site Operators

• Load balancing turns charger nameplate ratings into a probabilistic site design, allowing more chargers on a smaller grid connection.
• Dynamic allocation almost always outperforms static allocation for commercial sites with variable traffic.
• Demand charges can equal or exceed energy costs; load balancing is the primary tool for controlling them.
• Energy storage and solar generation multiply the value of load balancing by raising effective site capacity during peaks.
• Open protocols such as OCPP 1.6 and standards such as ISO 15118 prevent vendor lock-in and simplify integration.
• User communication and periodic tuning are essential for long-term success.

Conclusion

Load balancing is one of the most important technologies for making commercial EV charging economically viable. By distributing available power intelligently across multiple chargers, operators can serve more vehicles, reduce utility costs, avoid expensive upgrades, and improve customer satisfaction. Dynamic load balancing, supported by OCPP and integrated with energy storage, offers the best results for most commercial sites.

Whether you are planning a workplace charging installation, a fleet depot, or a public charging hub, load balancing should be part of your design from the beginning.

Ready to design a load-balanced charging site? Request a custom quote for your project, explore FBK POWER's Split-Type DC Charging Cabinet for high-throughput applications, or contact our engineering team to review your site constraints and vehicle mix.

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This article was researched using [OCPP 1.6 Load Management Specification](https://www.openchargealliance.org), [IEC 61851-1 Electric Vehicle Conductive Charging System](https://webstore.iec.ch/publication/66912), and [U.S. Department of Energy Demand Charge Analysis](https://afdc.energy.gov). Load management data references [NREL Fleet Charging Analysis](https://www.nrel.gov/fleet-charging) and [IEEE 2030.1.1 Smart Energy Profile](https://standards.ieee.org/standard/2030.1.1-2021.html).