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.

Mk2PVRouter diverter.

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

Only one mk2pvrouter hub is supported per device.

• id (Optional, ID): Manually specify the ID used for code generation.
• 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
R	Mean power for relay diversion	W	Single- and three-phase systems
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, …	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 converts this to volts/°C before publishing the sensor state, so any filters: you add run on the already-converted value, just like on any other sensor.

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. Not normally needed, since there is only one hub.
• All other options from Sensor.

Sensor defaults (unit, device class, state class, accuracy) are automatically set based on the tag name. You can override any of them by specifying the corresponding option explicitly.

Common tags (same defaults regardless of single- or three-phase setup):

Tag	Unit	Device Class	State Class	Accuracy	Notes
P	W	power	measurement	0	Total power at grid (on three-phase, P = P1 + P2 + P3)
R	W	power	measurement	0	Mean power for relay diversion (single- and three-phase)
T1, T2, …	°C	temperature	measurement	2	Automatically converted from centi-degrees
R1, R2, …	—	—	none	0	Relay state, 0/1
Any other tag (e.g. N)	—	—	measurement	0	Fallback defaults

Single-phase tags (bare letter):

Tag	Unit	Device Class	State Class	Accuracy	Notes
V	V	voltage	measurement	2	Automatically converted from centivolts
D	W	power	measurement	0	Diverted power
E	Wh	energy	total_increasing	0	Diverted energy (daily reset counter)

Three-phase tags (letter + phase/load number):

Tag	Unit	Device Class	State Class	Accuracy	Notes
P1, P2, P3	W	power	measurement	0	Power per phase
V1, V2, V3	V	voltage	measurement	2	Automatically converted from centivolts
D1, D2, …	%	—	measurement	0	Diversion rate per load

NOTE

In the tables above, a — cell means the component sets no default for that option, so ESPHome’s normal sensor defaults apply instead; none means the component explicitly clears the state class for that tag (relay states), which is what "" does when set from YAML.

NOTE

A tag’s defaults depend on whether the letter is bare or followed by a number, so D and R do not share defaults with D1/D2/… and R1/R2/…: a bare D is diverted power in watts, while D1/D2/… are diversion rates in percent with no device class. A bare T or an indexed E (such as E1) is not a Mk2PVRouter output and only gets the fallback defaults.

Binary Sensors

Relay state tags (R1, R2, …) can also be exposed as binary sensors: a value of 0 is published as OFF, any other value as ON.

binary_sensor:
  - platform: mk2pvrouter
    tag: "R1"
    name: "Relay 1"

• tag (Required, string): The tag to retrieve from the Telemetry.
• mk2pvrouter_id (Optional, ID): The ID of the mk2pvrouter hub to use. Not normally needed, since there is only one hub.
• All other options from Binary Sensor.

Text Sensors

Any tag can also be exposed as a text sensor, which publishes the raw value exactly as received, without numeric parsing or scaling. Values are limited to 7 characters; longer values are dropped by the hub.

text_sensor:
  - platform: mk2pvrouter
    tag: "S_MC"
    name: "S_MC raw"

• tag (Required, string): The tag to retrieve from the Telemetry.
• mk2pvrouter_id (Optional, ID): The ID of the mk2pvrouter hub to use. Not normally needed, since there is only one hub.
• All other options from Text Sensor.

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

See Also

• Mk2PVRouter documentation
• mk2Wifi-C6 expansion module
• Mk2PVRouter FW single phase
• Mk2PVRouter FW three phase
• API Reference: mk2pvrouter.h