Mk2PVRouter Surplus Energy Diverter

The mk2pvrouter component allows you to retrieve telemetry data from a Mk2PVRouter diverter and to control it via GPIO switches. It works with any Mk2PVRouter diverter, as long as the telemetry feature has been activated on the router itself.

This component can also be used to send data to a non-Home Assistant system via MQTT.

Hardware

The recommended hardware is the mk2Wifi-C6 expansion module, based on an ESP32-C6-MINI-1. It plugs directly into the mainboard via the TRIG_EXT and UART_EXT pin headers.

The module also provides:

MISC header — 4 additional GPIOs (GPIO19—GPIO22) for extra sensors or interfaces (e.g. I2C, 1-Wire, digital I/O)
OLED connector — a Molex SL 4-pin I2C connector (GPIO6 SDA, GPIO7 SCL) for an optional display

NOTE

Any ESP32 board can be used instead of the mk2Wifi module. In that case, adapt the GPIO pin numbers in the examples below to match your wiring.

Wiring

With the mk2Wifi module, connections are handled automatically through the TRIG_EXT and UART_EXT pin sockets. No extra wiring is needed.

If using a standalone ESP32, connect the TX pin of the Mk2PVRouter mainboard to the RX pin of your ESP module. No TX connection from ESP to the mainboard is needed (communication is one-way).

UART Configuration

The communication uses UART with specific settings: 9600 baud, 7 data bits, even parity, 1 stop bit.

On the mk2Wifi module, the mainboard transmits on UART_TX which is connected to the ESP32-C6 GPIO17 (U0RXD), and GPIO16 (U0TXD) is connected to UART_RX.

NOTE

GPIO16 and GPIO17 are the default UART0 pins on the ESP32-C6, so this configuration uses the hardware UART without requiring any pin remapping.

# mk2Wifi-C6 configuration
uart:
  rx_pin: GPIO17
  baud_rate: 9600
  parity: EVEN
  data_bits: 7
  stop_bits: 1

mk2pvrouter:

Configuration Variables

id (Optional, ID): Manually specify the ID used for code generation or multiple hubs.
uart_id (Optional, ID): Manually specify the ID of the UART Component if you want to use multiple UART buses.

Available Tags

The tags available depend on your Mk2PVRouter configuration. Common tags include:

Tag	Description	Unit	Notes
`P`	Total power at grid	W	Positive = importing, Negative = exporting
`P1`, `P2`, `P3`	Power per phase	W	Three-phase systems only
`V`	Voltage (single-phase)	V	Sent in centivolts; converted automatically
`V1`, `V2`, `V3`	Voltage per phase	V	Three-phase systems only; converted automatically
`D`	Diverted power	W	Single-phase systems
`D1`, `D2`, `D3`	Diversion rate per load	%	Three-phase systems
`E`	Diverted energy	Wh	Single-phase systems
`T1`, `T2`, …	Temperature sensors	°C	Sent in centi-degrees; converted automatically
`R1`, `R2`, …	Relay states	0/1	0 = OFF, 1 = ON
`N`	No-diversion counter	-	Count of cycles without diversion

NOTE

Voltage and temperature values are sent multiplied by 100 (centivolts/centi-degrees). For V/V1/V2/V3 and T1, T2, … tags, the component automatically applies a built-in multiply: 0.01 filter so the published value is already in volts or °C.

This built-in filter stacks on top of any filters: you add to the sensor — it does not replace them. If you add your own filters to one of these tags, they run after the built-in multiply: 0.01 conversion. For example, adding multiply: 0.001 on a V tag results in an effective conversion of 0.01 * 0.001, i.e. the value ends up in kilovolts, not volts. Take this into account when writing filters for these tags — do not add your own multiply: 0.01 expecting to perform the base conversion, or the value will be scaled twice.

Sensors

sensor:
  - platform: mk2pvrouter
    tag: "P"
    name: "Power at grid"
  - platform: mk2pvrouter
    tag: "V1"
    name: "Voltage Phase 1"
  - platform: mk2pvrouter
    tag: "D1"
    name: "Diversion rate Load 1"

tag (Required, string): The tag to retrieve from the Telemetry.
mk2pvrouter_id (Optional, ID): The ID of the mk2pvrouter hub to use, if you have multiple.
All other options from Sensor.

NOTE

Sensor defaults (unit, device class, accuracy) are automatically set based on the tag name. You can override them if needed.

Complete Example

Here’s a complete configuration for a three-phase system using the mk2Wifi-C6 module:

esphome:
  name: pvrouter-monitor

esp32:
  board: esp32-c6-devkitm-1

logger:
  level: DEBUG

wifi:
  ssid: !secret wifi_ssid
  password: !secret wifi_password

api:
  encryption:
    key: !secret api_key

ota:
  - platform: esphome

uart:
  rx_pin: GPIO17
  baud_rate: 9600
  parity: EVEN
  data_bits: 7
  stop_bits: 1

mk2pvrouter:

sensor:
  - platform: mk2pvrouter
    tag: "P"
    name: "Total Power"
    id: total_power
  - platform: mk2pvrouter
    tag: "P1"
    name: "Power Phase 1"
  - platform: mk2pvrouter
    tag: "P2"
    name: "Power Phase 2"
  - platform: mk2pvrouter
    tag: "P3"
    name: "Power Phase 3"
  - platform: mk2pvrouter
    tag: "V1"
    name: "Voltage Phase 1"
    id: voltage_phase1
  - platform: mk2pvrouter
    tag: "V2"
    name: "Voltage Phase 2"
  - platform: mk2pvrouter
    tag: "V3"
    name: "Voltage Phase 3"

Controlling the Mk2PVRouter

The mk2Wifi module provides up to 5 trigger/control outputs (D5—D9) connected to the mainboard via the TRIG_EXT header. These GPIOs can control functionalities on the Mk2PVRouter.

NOTE

The solder jumpers for D5—D9 on the mk2Wifi board are open by default. You must close the corresponding jumper for each control output you want to use.

The GPIO mapping on the mk2Wifi-C6 module is:

Signal	GPIO
D5	GPIO0
D6	GPIO5
D7	GPIO4
D8	GPIO3
D9	GPIO1

NOTE

GPIO4 and GPIO5 are strapping pins on the ESP32-C6. ESPHome logs a strapping-pin warning at compile time when they are used as outputs, which is expected here since the module’s PCB dictates this pin assignment. Add ignore_strapping_warning: true to the pin config to silence it.

Common control functions include:

Diversion ON/OFF - Enable or disable energy diversion
Forced mode - Force the heater ON regardless of surplus energy
Priority selection - Switch between load priorities
Temperature override - Override temperature-based controls

switch:
  - platform: gpio
    pin: GPIO0
    name: "Diversion ON/OFF"
    inverted: true
    restore_mode: RESTORE_DEFAULT_ON

  - platform: gpio
    pin: GPIO5
    name: "Forced Mode"
    inverted: true
    restore_mode: RESTORE_DEFAULT_OFF

  # Additional controls (optional)
  # - platform: gpio
  #   pin: GPIO4
  #   name: "Priority Select"
  #   inverted: true
  #   restore_mode: RESTORE_DEFAULT_OFF
  #
  # - platform: gpio
  #   pin: GPIO3
  #   name: "Temperature Override"
  #   inverted: true
  #   restore_mode: RESTORE_DEFAULT_OFF

NOTE

The Mk2PVRouter digital inputs are active-low by default, so inverted: true is required for correct operation (ON in Home Assistant = LOW on the GPIO = active on the router).

TIP

Use restore_mode to define the switch state after reboot:

RESTORE_DEFAULT_ON - Restore previous state, default to ON
RESTORE_DEFAULT_OFF - Restore previous state, default to OFF
ALWAYS_ON / ALWAYS_OFF - Always start in a specific state

Optional Peripherals

The mk2Wifi-C6 module supports additional peripherals through its connectors.

OLED Display

An I2C OLED display (e.g. SSD1306 128x64) can be connected to the OLED Molex SL connector (GPIO6 SDA, GPIO7 SCL). See SSD1306 for full configuration options.

i2c:
  sda: GPIO6
  scl: GPIO7

font:
  - file: "gfonts://Roboto"
    id: roboto
    size: 14

display:
  - platform: ssd1306_i2c
    model: "SSD1306 128x64"
    lambda: |-
      it.printf(0, 0, id(roboto), "P: %.0f W",
                id(total_power).state);
      it.printf(0, 20, id(roboto), "V: %.1f V",
                id(voltage_phase1).state);

DS18B20 Temperature Sensor

The mainboard’s DS18B20 1-Wire signal is passed through the UART_EXT connector to GPIO23. See Dallas Temperature for details.

one_wire:
  - platform: gpio
    pin: GPIO23

sensor:
  - platform: dallas_temp
    name: "Water Temperature"

MISC Header

The 4 GPIOs on the MISC header (GPIO19—GPIO22) can be used as digital inputs, outputs, or for additional buses.

For example, you can connect the S0 pulse output of an energy meter on the diverted load to track actual diverted energy. See Pulse Counter and Total Daily Energy for full configuration options.

sensor:
  - platform: pulse_counter
    pin:
      number: GPIO19
      mode: INPUT_PULLUP
    id: diverted_power_meter
    name: "Diverted Power (meter)"
    unit_of_measurement: "W"
    internal_filter: 50ms
    filters:
      - multiply: 60  # 1000 pulses/kWh -> W conversion
  - platform: total_daily_energy
    name: "Diverted Energy Today"
    power_id: diverted_power_meter

MQTT Integration

WARNING

If you enable MQTT forwarding and do not use the Native API (i.e., the module is exclusively used for forwarding data via MQTT and is not connected to any Home Assistant instance), you must remove the api: configuration or set reboot_timeout: 0s, otherwise the ESP will reboot every 15 minutes.

If you configure MQTT, you need to define the MQTT component. Like any other ESPHome entity, each sensor is published to a topic following this structure: <topic_prefix>/<component_type>/<object_id>/state, where <object_id> is the sanitized (lowercase, underscored) version of the entity’s name. Use state_topic on the entity if you need a different topic.

mqtt:
  broker: 192.168.1.10
  port: 1883
  username: !secret mqtt_username
  password: !secret mqtt_password
  topic_prefix: "mk2pvrouter"

mk2pvrouter:

With this configuration, using the sensors named “Voltage Phase 1” and “Total Power” from the Complete Example above, data will be published to topics such as:

mk2pvrouter/sensor/voltage_phase_1/state
mk2pvrouter/sensor/total_power/state

Mk2PVRouter Surplus Energy Diverter

Hardware

Wiring

UART Configuration

Configuration Variables

Available Tags

Sensors

Complete Example

Controlling the Mk2PVRouter

Optional Peripherals

OLED Display

DS18B20 Temperature Sensor

MISC Header

MQTT Integration

See Also