An ESPHome component that allows an ESP device to emulate the Pylontech RS485 low-voltage battery protocol. This enables the use of DIY batteries or other battery management systems (like YAM-BMS) with inverters that expect to communicate with a Pylontech-compatible BMS.

• Dynamic Data: Takes live data from ESPHome sensors to report battery status.
• Highly Configurable: All parameters are configurable through your ESPHome YAML file.
• Protocol Emulation: Replicates specific protocol quirks for compatibility with certain inverter brands.

This component has been confirmed to work across a wide range of popular inverter brands, making it a reliable choice for emulating a Pylontech battery. Its design ensures it can handle both standard and non-standard variations of the RS485 protocol.

Confirmed Compatible Inverters:

• Growatt
• Deye / Sol-Ark
• SRNE / EcoWorthy (All-in-One models)

Given this broad compatibility, it is highly likely that this component will work with other inverters that support the Pylontech low-voltage RS485 protocol.

We need your help! If you have successfully used this component with an inverter not on this list, please open an issue or PR to let us know so we can add it to this list.

Robust by Design: The Origin Story

The Pylontech RS485 protocol is not a strict standard. This component was originally developed by reverse-engineering the protocol for a particularly demanding SRNE inverter, which required implementing specific non-standard quirks (like a fixed response address and a unique frame length calculation).

The happy result is an emulator robust enough to handle these difficult variations, which is why it also works seamlessly with more standard inverter implementations like those from Growatt and Deye. You can be confident that the emulation is accurate and resilient.

To use this component, you will need:

• An ESP32 or ESP8266 based development board.
• An RS485 to TTL converter module (e.g., MAX485 module) to interface with the inverter's RS485 port.

To include this component in your ESPHome project, add the following to your YAML configuration file:

external_components:
  - source: github://fahmula/esphome-pylontech-rs485@main
    refresh: 0s # Optional: Set to a duration (e.g., 1h) to periodically check for updates

The pylontech_rs485 component is configured under its own block in your ESPHome YAML file.

pylontech_rs485:
  uart_id: uart_bus # REQUIRED: Link to the UART bus defined elsewhere in your YAML
  
  # --- Core Data (Required for basic operation) ---
  state_of_charge: live_soc
  voltage: live_voltage
  current: live_current
  temperature: live_temperature

  # --- Dynamic Battery Limits (Required for basic operation) ---
  max_voltage: live_max_v
  min_voltage: live_min_v
  max_charge_current: live_max_charge_i
  max_discharge_current: live_max_discharge_i

  # --- Optional Health & Detail Sensors (for full protocol compliance) ---
  # state_of_health: live_soh
  # cycle_count: live_cycle_count
  # max_cell_voltage: live_max_cell_v
  # min_cell_voltage: live_min_cell_v
  # max_temperature: live_max_temp
  # min_temperature: live_min_temp
  # mosfet_temperature: live_mosfet_temp
  # max_mosfet_temperature: live_max_mosfet_temp
  # min_mosfet_temperature: live_min_mosfet_temp
  # bms_temperature: live_bms_temp
  # max_bms_temperature: live_max_bms_temp
  # min_bms_temperature: live_min_bms_temp

  # OPTIONAL: Configure the sensor update timeout
  # If no new data is received from the linked sensors for this duration,
  # the component will stop talking to the inverter.
  # Default: 60s
  update_timeout: 60s

  # --- Optional RS485 Link Monitoring ---
  # These sensors help monitor the health of the RS485 communication
  # link between the ESPHome device and the inverter.
  # rs485_status: link_status
  # inverter_heartbeat: link_heartbeat
  # heartbeat_switch: link_heartbeat_enable

  # --- Optional Alarm and Protection Binary Sensors ---
  # Uncomment and link to ESPHome binary_sensor entities to report alarm and protection statuses.
  # These are typically used for simulation/testing purposes with the pylontech-emulator-example.yaml.
  #
  # Alarm Status 1
  # total_voltage_high_alarm: alarm_total_voltage_high
  # total_voltage_low_alarm: alarm_total_voltage_low
  # cell_voltage_high_alarm: alarm_cell_voltage_high
  # cell_voltage_low_alarm: alarm_cell_voltage_low
  # cell_temp_high_alarm: alarm_cell_temp_high
  # cell_temp_low_alarm: alarm_cell_temp_low
  # mosfet_temp_high_alarm: alarm_mosfet_temp_high
  # cell_imbalance_alarm: alarm_cell_imbalance
  #
  # Alarm Status 2
  # cell_temp_imbalance_alarm: alarm_cell_temp_imbalance
  # charge_overcurrent_alarm: alarm_charge_over_current
  # discharge_overcurrent_alarm: alarm_discharge_over_current
  #
  # Protection Status 1
  # module_overvoltage_protection: protection_module_overvoltage
  # module_undervoltage_protection: protection_module_undervoltage
  # cell_overvoltage_protection: protection_cell_overvoltage
  # cell_undervoltage_protection: protection_cell_undervoltage
  # cell_overtemp_protection: protection_cell_over_temperature
  # cell_undertemp_protection: protection_cell_under_temperature
  # mosfet_overtemp_protection: protection_mosfet_over_temperature
  #
  # Protection Status 2
  # charge_overcurrent_protection: protection_charge_over_current
  # discharge_overcurrent_protection: protection_discharge_over_current
  # system_fault_protection: protection_system_fault

  # --- Other Optional Sensors ---
  # requested_force_charge: my_force_charge_sensor

• uart_id (Required): The ID of the uart bus component used for RS485 communication with the inverter.

• Core Data Sensors (Required for basic operation):

  • state_of_charge (Required): The ID of an ESPHome sensor entity that provides the current State of Charge (SoC) as a percentage (0-100).
  • voltage (Required): The ID of an ESPHome sensor entity that provides the current battery voltage in Volts.
  • current (Required): The ID of an ESPHome sensor entity that provides the current battery current in Amperes. Positive for charging, negative for discharging.
  • temperature (Required): The ID of an ESPHome sensor entity that provides the current battery temperature in Celsius.

• Dynamic Battery Limits Sensors (Required for basic operation):

  • max_voltage (Required): The ID of an ESPHome sensor entity that provides the maximum allowed battery charge voltage in Volts.
  • min_voltage (Required): The ID of an ESPHome sensor entity that provides the minimum allowed battery discharge voltage in Volts.
  • max_charge_current (Required): The ID of an ESPHome sensor entity that provides the maximum allowed charging current in Amperes.
  • max_discharge_current (Required): The ID of an ESPHome sensor entity that provides the maximum allowed discharging current in Amperes.

• Optional Health & Detail Sensors (for full protocol compliance):

  • state_of_health (Optional): The ID of an ESPHome sensor entity that provides the State of Health (SoH) as a percentage (0-100).
  • cycle_count (Optional): The ID of an ESPHome sensor entity that provides the total battery cycle count.
  • max_cell_voltage (Optional): The ID of an ESPHome sensor entity that provides the maximum cell voltage in Volts.
  • min_cell_voltage (Optional): The ID of an ESPHome sensor entity that provides the minimum cell voltage in Volts.
  • max_temperature (Optional): The ID of an ESPHome sensor entity that provides the maximum cell temperature in Celsius.
  • min_temperature (Optional): The ID of an ESPHome sensor entity that provides the minimum cell temperature in Celsius.
  • mosfet_temperature (Optional): The ID of an ESPHome sensor entity that provides the average MOSFET temperature in Celsius.
  • max_mosfet_temperature (Optional): The ID of an ESPHome sensor entity that provides the maximum MOSFET temperature in Celsius.
  • min_mosfet_temperature (Optional): The ID of an ESPHome sensor entity that provides the minimum MOSFET temperature in Celsius.
  • bms_temperature (Optional): The ID of an ESPHome sensor entity that provides the average BMS temperature in Celsius.
  • max_bms_temperature (Optional): The ID of an ESPHome sensor entity that provides the maximum BMS temperature in Celsius.
  • min_bms_temperature (Optional): The ID of an ESPHome sensor entity that provides the minimum BMS temperature in Celsius.

• update_timeout (Optional, default: 60s): The duration after which, if no new data is received from the linked sensors, the component will stop sending data to the inverter.

• RS485 Link Monitoring (Optional):

  • rs485_status (Optional): The ID of an ESPHome binary_sensor that reflects the communication status with the inverter. It turns ON when communication is active and OFF on timeout.
  • inverter_heartbeat (Optional): The ID of an ESPHome sensor that measures the interval (in milliseconds) between heartbeat messages from the inverter. Can be used to detect a frozen or slow communication link.
  • heartbeat_switch (Optional): The ID of an ESPHome switch to enable or disable the inverter_heartbeat sensor.

• Optional Alarm and Protection Binary Sensors:

  • total_voltage_high_alarm (Optional): The ID of an ESPHome binary_sensor entity that indicates if the total battery voltage is too high.
  • total_voltage_low_alarm (Optional): The ID of an ESPHome binary_sensor entity that indicates if the total battery voltage is too low.
  • cell_voltage_high_alarm (Optional): The ID of an ESPHome binary_sensor entity that indicates if any cell voltage is too high.
  • cell_voltage_low_alarm (Optional): The ID of an ESPHome binary_sensor entity that indicates if any cell voltage is too low.
  • cell_temp_high_alarm (Optional): The ID of an ESPHome binary_sensor entity that indicates if any cell temperature is too high.
  • cell_temp_low_alarm (Optional): The ID of an ESPHome binary_sensor entity that indicates if any cell temperature is too low.
  • mosfet_temp_high_alarm (Optional): The ID of an ESPHome binary_sensor entity that indicates if the MOSFET temperature is too high.
  • cell_temp_imbalance_alarm (Optional): The ID of an ESPHome binary_sensor entity that indicates if there is a cell temperature imbalance.
  • cell_imbalance_alarm (Optional): The ID of an ESPHome binary_sensor entity that indicates if there is a cell voltage imbalance.
  • charge_overcurrent_alarm (Optional): The ID of an ESPHome binary_sensor entity that indicates if there is a charge overcurrent alarm.
  • discharge_overcurrent_alarm (Optional): The ID of an ESPHome binary_sensor entity that indicates if there is a discharge overcurrent alarm.
  • module_overvoltage_protection (Optional): The ID of an ESPHome binary_sensor entity that indicates if module overvoltage protection is active.
  • module_undervoltage_protection (Optional): The ID of an ESPHome binary_sensor entity that indicates if module undervoltage protection is active.
  • cell_overvoltage_protection (Optional): The ID of an ESPHome binary_sensor entity that indicates if cell overvoltage protection is active.
  • cell_undervoltage_protection (Optional): The ID of an ESPHome binary_sensor entity that indicates if cell undervoltage protection is active.
  • cell_overtemp_protection (Optional): The ID of an ESPHome binary_sensor entity that indicates if cell overtemperature protection is active.
  • cell_undertemp_protection (Optional): The ID of an ESPHome binary_sensor entity that indicates if cell undertemperature protection is active.
  • mosfet_overtemp_protection (Optional): The ID of an ESPHome binary_sensor entity that indicates if MOSFET overtemperature protection is active.
  • charge_overcurrent_protection (Optional): The ID of an ESPHome binary_sensor entity that indicates if charge overcurrent protection is active.
  • discharge_overcurrent_protection (Optional): The ID of an ESPHome binary_sensor entity that indicates if discharge overcurrent protection is active.
  • system_fault_protection (Optional): The ID of an ESPHome binary_sensor entity that indicates if system fault protection is active.

• Other Optional Sensors:

  • requested_force_charge (Optional): The ID of an ESPHome binary_sensor. When this sensor is ON, the component will signal to the inverter to request an immediate charge.

This component is designed to be controlled by standard ESPHome sensor entities. This allows you to feed it live battery data from any source, such as:

• A dedicated BMS (Battery Management System) connected to your ESP device.
• Template sensors that calculate values based on other inputs.
• Input helpers (e.g., number entities in Home Assistant) for manual testing and simulation.

The pylontech_rs485 component simply reads the state of the sensor entities you link to its configuration parameters.

The pylontech-emulator-example.yaml file in this repository provides a complete configuration for manual testing. This example sets up number entities (sliders) in Home Assistant, allowing you to simulate various battery parameters and observe the inverter's response.

1. Global Variables: globals are defined to store the current values of the simulated battery parameters (e.g., g_soc, g_voltage). These values are restored on reboot.
2. Home Assistant Sliders (number entities): number entities are created, linked to the global variables. These appear as sliders in Home Assistant, allowing you to manually adjust the simulated SoC, voltage, current, etc. When you move a slider, its set_action updates the corresponding global variable.
3. Live Data Sensors (template sensor entities): template sensor entities are defined. These sensors simply read the current state of the Home Assistant sliders (which in turn reflect the global variables).
4. Pylontech Component Linkage: The pylontech_rs485 component is configured to read its required data (SoC, voltage, current, etc.) directly from these template sensor entities.

This setup creates a clear data flow, allowing you to easily test the component's behavior with your inverter.

graph TD
    subgraph Home Assistant UI
        A[Sliders for Voltage, SoC, etc.]
    end

    subgraph ESPHome Device
        B(Globals e.g., g_voltage)
        C(Template Sensors e.g., live_voltage)
        D[pylontech_rs485 Component]
    end

    subgraph Inverter
        E[Inverter]
    end

    A -- "set_action" --> B
    B -- "lambda" --> C
    C -- "feeds data to" --> D
    D -- "RS485" --> E

• Add support for other inverters if needed.

Contributions are welcome! If you get this working with a different inverter brand, please open an issue or pull request to share your findings.