straybiker / HA-load-balancer

EV load balancer for Home Assistant tailored to Belgium energy regulation

Home Assistant Car Charging Load Balancer Automation

A car charging load balancer for Home Assistant tailored to Belgian energy regulation (Capaciteitstarief).

Table of Contents

• Introduction
• Features
• Prerequisites
• Installation
• Details
• Configuration and Helpers
• Future Developments
• Disclaimer
• Troubleshooting
• Contributing
• License

Introduction

This Home Assistant automation provides intelligent load balancing for EV charging, designed to minimize energy costs and avoid exceeding your maximum power limit (capaciteitspiek) under Belgian energy regulations. By dynamically adjusting the charging phases and current based on your household's power consumption, this system helps you charge your EV efficiently without exceeding a set peak power (capaciteitstarief).

This project is ideal for users with an EV charger that can switch phases and adjust current, such as the Alfen Eve Pro wallbox. The load balancer can also be made car-aware, where the current SOC is taken into account to reach a minimum SOC at a set time.

This is not a fully-fledged Home Assistant integration (yet), but a package that can easily be integrated into your existing Home Assistant setup.

Important

The separate YAML files are deprecated and archived in the archive folder.

Features

• Dynamically adjusts EV charging based on household power consumption.
• Supports 3-phase electrical installations.
• Car-aware functionality to meet minimum SOC targets by a set time.
• Configurable modes: Off, Fixed (1.4kW or 4kW), Limited, Fast and Comfort.
• Handles charger efficiency and measurement noise with filtering.
• Phase switching protection to prevent frequent switching between 1 and 3 phases on days with alternating sun and clouds.

Prerequisites

• 3-phase electrical installation: 1-phase only is not yet supported.
• EV charger integration: Only 1 socket is currently supported.
  • For the Alfen Eve Pro, install the Home Assistant HACS Alfen Wallbox integration: Alfen Wallbox Integration. Ensure active load balancing is disabled on the Alfen charger to avoid conflicts. Minimum version: 2.9.4.
• Household power consumption sensor excluding charger power consumption.

Tip

If you can't measure the household power consumption seperately, create helpers to calculate the to subtract the charger power from the total power consumption

Installation

Step 1: Package Installation

Follow the Home Assistant package documentation for installation details. The package file is located in the package folder.

Step 2: Configuration

Update the configuration section to your specific setup and check the configuration from the developer YAML section. If you don't need Car Aware functionality, the settings in the car configuration can be emptied

Tip

Use a low-pass filter to smooth noisy household power consumption data. Example configuration:

platform: filter
name: "Netto verbruik huis LP"
unique_id: netto_verbruik_huis_lp
entity_id: sensor.netto_verbruik_huis
filters:
  - filter: outlier
    window_size: 4
    radius: 500.0
  - filter: lowpass
    time_constant: 12
    precision: 2

Here, sensor.netto_verbruik_huis is the raw household power consumption, and netto_verbruik_huis_lp is the filtered value used by the load balancer.

Tip

For PV-aware charging, use a low-pass filter to prevent excessive switching by cloud coverage. Example configuration:

platform: filter
name: "PV Power LP"
unique_id: pv_power_lp
entity_id: sensor.sma_power_w
filters:
  - filter: outlier
    window_size: 3
    radius: 1000.0
  - filter: lowpass
    time_constant: 5
    precision: 0

Step 3: Update script

The script to set the charger parameters currently supports the Alfen Eve Pro Single charger. Update the script to the outputs according to your charger.

Note

The charger connection states are based on the IEC-61851 standard. If your charger is not compliant to this standard, you need to update the state mapping.

Step 4: Reload

Restart Home Assistant

Step 5: Set parameters

Set the helpers that are now available in the UI to the desired values.

Details

This load balancer checks every 10 seconds the current household power consumption and sets the charger output parameters, phase and current, according to the remaining available power. The total allowed power to use (capaciteitspiek), household + EV charger, is defined in an input helper parameter. The load balancer also takes charger efficiency into account by comparing the calculated power output with the actual power output.

Note

The maximum current can still be limited by the settings of the car. This setting can be checked by the external socket max current sensor.

Important

This load balancer switches between 3 phases power and a max current of 16A. 1 phase only is not supported.

Here, during charging, the power is kept stable around 6000W, although major changes in the household power consumption. At 18h, the car was disconnected for a while. The spikes are measurement errors.

The current script also checks the battery state of a car. When forecasted battery percentage doesn't reach a minimum charge by a set time, the charger can override the maximum power to a second limit. If the threshold is reached, charging will just continue until the car stops the session. For example, I want my car to be 80% charged by 8:00 in the morning. If it cannot reach 80%, some additional power can be consumed. Set both power parameters equal to disable the extra power consumption.

If there is not enough power to charge at 3 phases, 6A, the charger is switched to 1 phase. When the remaining power is not enough to reach 1 phase, 6A, charging stops by setting the maximum socket current to 0A. There is a risk with this that the car is not charged for a prolonged period if household power consumption is high.

Note

There is a built in dynamic delay in the script when the charger parameters are changed. There will be no update sent to the charger until the setting is updated or a time-out in the script occurs.

When the charger is disconnected, the charger phases and current are set to a default value. This way you shouldn't end up with a charger that is set to 0A when Home Assistant is not available.

Warning

There is still a risk if Home Assistant becomes unavailable during charging with the charger set at 0A. Then you need to configure the charger directly on the charger such as Eve Connect app or ACE Service Installer for the Alfen Eve Pro. Check your charger's manufacturer manual.

Charge Modes

The available charge modes are:

• Off: Charging disabled
• Fixed 1.4kW: Single phase charging at 6A (1.4kW)
• Fixed 4kW: Three phase charging at 6A (4kW)
• Limited: Dynamic power limiting based on household consumption
• Fast: Full speed charging at maximum current
• Solar: Dynamic power based on solar production
• Comfort: Behave as Limited below a SOC setting and as Solar above to guarantee a minimal SOC.

Configuration and helpers

Update the following variables in the script with your own sensors and parameters. The parameters can be hard coded or set with a helper variable if you want to control it from the UI

Load balancer

Variable	Unit	Type	Description
state	string	Parameter.	Load balancer mode [Off, Fixed 1.4kW, Fixed 4kW, Fast, Limited, Solar, Comfort]
car_aware	bool	Parameter.	Enable car aware functionality [true, false] for Limied mode
power_limit	W	Parameter	Maximum power consumption limit including charging.
power_limit_extended	W	Parameter	[Optional] Maximum power allowed overcharge to reach SOC
pv_prioritized	bool	Parameter	Enable to make maximum use of solar power
single_phase_only	bool	Parameter	Limit to phase output to 1 phase only

Charger

Variable	Unit	Type	Description
active_power	W	Sensor	Current active power of the charger to calculate charger efficiency.
connection_state		Sensor	Connection state of the changer. [Disconnected, Connected]
current_input	A	Sensor	Active current of the charger.
current_output	A	Output entity	Current setting of the charger.
default_current	A	Parameter	Default current to reset the charger of diconnecting.
default_phases		Parameter	Default phase selection to reset the charger after disconnecting. Charger dependant
max_current	A	Parameter	Maximum supported current of the charger.
min_current	A	Parameter	Minimum supported current of the charger.
nominal_voltage	V	Parameter	Nominal operating voltage of the charger.
phases_input		Sensor	Active selected phases of the charger. Charger dependat
phases_output		Output entity	Phases setting of the charger. Charger dependant

Household

Variable	Unit	Type	Description
household_power	W	Sensor	Smoothed household power consumption excluding the charger.
pv_power	W	Sensor	[Optional] Smoothed PV generated power.

Car

Car configuration is optional and only needed when car_aware is enabled in the load balancer

Variable	Unit	Type	Description
min_current	A	Parameter	Minimum supported car current.
max_current	A	Parameter	Maximum supported car current.
battery_percentage	%	Sensor	Current battery percentage of the car. [0%-100%]
battery_capacity_wh	Wh	Parameter	Battery capacity of the car.
soc_threshold	%	Parameter	Required battery percentage to reach by a set time. [0%-100%]
target_time	Time [HH:SS]	Parameter	Time by which the SOC threshold should be reached.

Tip

Once the monthly peak consumption passes the set power limit of the loadbalancer, you can increase this limit to the new monthly peak via an automation. Do not forget to reset this at the beginning of the month.

Features

PV optimalization for modes Limited, Solar and Comfort

• pv_prioritized is only applicable to Limited mode and when enabled, the car will charge purely on solar power if the remaining solar power, not consumed by household consumption, is enough to charge the car. If there is not enough solar power, power from the grid will be used to charge up to power_limit. This combination is usefull to use as much solar power as possible but make sure the car is charged in the end.
• With Solar charging, only remaining solar power is used. If this is not enough to charge the car, loading stops. This is useful if only need to be charged a little or the charger can be connected for 2 days or longer, such as in the weekend. -In Comfort mode, the system behaves as Limited when the current SOC is below the minimum set and as Solar above. This is not the same as Limited with pv_prioritized enabled. In Comfort, charging stops when the minimum required SOC is reached, while in Limited it continues till the car is fully charged, using either solar or grid power. During the Limited cycle, car_aware and pv_prioritized are taken into account.

Efficiency Handling

The system accounts for charger efficiency in all power calculations, by comparing the theoretical output with the real output:

• Available power is adjusted using measured charger efficiency
• Phase selection considers efficiency losses
• Current calculations include efficiency compensation
• Efficiency is calculated dynamically based on actual power measurements
• Fallback to 100% efficiency when no valid measurements available

Car-aware Mode Behavior

When car-aware mode is enabled (car_aware: true), the system checks for required car sensors:

• battery_percentage
• battery_capacity_wh
• soc_time
• soc_threshold

If any of these sensors are unavailable the system continues operating as were car_aware=false

The current and phase limits are determined as follows:

• With car_aware=true: Uses minimum of car and charger max current
• With car_aware=false: Uses charger defaults
• With unavailable car sensors: Falls back to charger defaults

Single Phase Operation

The load balancer can be configured to operate in single phase mode only:

• Toggle Single Phase Only in the configuration to force single phase operation
• When enabled:
  • All modes will operate in single phase regardless of power availability
  • Fast mode will still use maximum current but only on single phase. This is the same as Fixed 4kW mode.
  • Fixed 4kW mode will be limited to single phase operation. This is the same as Fast mode.
  • Limited and Solar modes will calculate optimal current for single phase
• Use this option if:
  • Your installation only supports single phase charging
  • You want to minimize the impact on phase balancing
  • You prefer consistent single phase operation

Frequent Phase Switching Protection

The load balancer includes a phase switching protection mechanism to prevent frequent switches between 1 and 3 phases:

• When switching from 3 phases to 1 phase in Limied or Solar mode, a timer is started. Default 5 minutes.
• During this period, the charger will not switch back to 3 phases even if more power becomes available. However, the utilization of the current is maximized on 1 phase.
• This protection does not apply to manual mode changes (e.g., switching to "Fixed 1.4kW" or "Fixed 4kW")
• The timer duration can be adjusted in the timer.ev_load_balancer_phase_switching_timer configuration

Robust Sensor Validity Check and Fallback

If any required sensor or attribute for the selected charge mode is unavailable, unknown, none, or non-numeric, the automation will:

• Log an error to Home Assistant's system log: [EV Load Balancer] Fallback to default charger values due to missing or invalid sensor data.
• Set the charger to its default current and phase, skipping all further logic.

Future Developments

• Autocalculate charger efficiency.
• Make car awareness optional.
• Option to prioritize PV consumption.
• Phase switching protection
• Optimize for dynamic energy contracts.
• Provide as generic a Home Assistant package.
• Option to limit to 1 phase only.
• Implement a minimum charge power instead of switching off the charger.
• Convert to a full Home Assistant integration.

Disclaimer

The use of this automation is at your own risk. The author assumes no responsibility for any consequences arising from its use, including power consumption, vehicle SOC, or damages. Test thoroughly in your environment before relying on it for critical operations.

Troubleshooting

Common Issues

1. Missing or Invalid Sensor Data

   • If any required sensor becomes unavailable, the charger falls back to default values
   • Check Home Assistant logs for "[EV Load Balancer] Fallback" messages
   • Verify all required sensors are properly configured and responding

2. Phase Switching Issues

   • The timer prevents rapid phase switching
   • Check if the phase switching timer is working correctly
   • Verify charger's phase switching capability

3. Car Awareness Not Working

   • Ensure car_aware is enabled
   • Verify all car-related sensors are available and providing valid data
   • Check if target time and SOC threshold are properly set

Debug Logging

To enable debug logging, add the following to your configuration.yaml:

logger:
  default: info
  logs:
    custom_components.ev_load_balancer: debug

Contributing

Contributions are welcome! Please feel free to submit a Pull Request. For major changes:

1. Fork the repository
2. Create your feature branch (git checkout -b feature/AmazingFeature)
3. Commit your changes (git commit -m 'Add some AmazingFeature')
4. Push to the branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

License

This project is licensed under the MIT License - see the LICENSE file for details.