Home Assistant: PV surplus, hot water: heating element

Besides the Control my heat pump I can alternatively heat the hot water via a switchable socket and a heating rod. Since my heat pump can only heat the water up to 50°C, the heating rod allows me to generate higher temperatures. If the hot water is heated by an additional 10°C on a day with sufficient sunshine, no hot water heating is required the following day. If the forecast for the expected PV harvest day for the following day falls below a certain value, I have put together an automation to heat the hot water more than usual with the PV electricity generated. Here is the automation in practice:

Legend: Green: PV power generation, Red: consumption; Yellow: heat pump; Dark red: heating rod

Automation in detail

Trigger	Description
When meter_power is below -3000 for 6:00	meter_power reflects the data of the smart meter: negative values (-) mean a power surplus ID: surplus
When heating.hot water is above 60	If the hot water is above 60°C, the corresponding action should turn off:
When meter_power is above 0	no more PV power surplus

Trigger

Description

When meter_power is below -3000 for 6:00

meter_power reflects the data of the smart meter: negative values (-) mean a power surplus

ID: surplus

When heating.hot water is above 60

If the hot water is above 60°C, the corresponding action should turn off:

When meter_power is above 0

no more PV power surplus

Actions

[+]

Actions:

'Turn on hot water switch' execute if 'Confirm meter_power is below -3000, Confirm heating.hot water is below 60, and Confirm Pv production tomorrow is below 20' otherwise 'Turn off hot water switch'.

If*:

When triggered by surplus.

Confirm heating.hot is above 48 and below 60

Confirm Pv production tomorrow is below 20

Then*:

Turn on hot water switch

Otherwise:

Switch off hot water switch

YAML-Datei

[+]

alias: "Surplus: hot water heater"
description: ""
trigger:
  - platform: numeric_state
    entity_id: sensor.meter_power
    for:
      hours: 0
      minutes: 6
      seconds: 0
    below: -3000
    id: Überschuss
  - platform: numeric_state
    entity_id: sensor.heating_warmwasser
    above: 60
  - platform: numeric_state
    entity_id: sensor.meter_power
    above: 0
condition: []
action:
  - if:
      - condition: trigger
        id:
          - Überschuss
      - condition: numeric_state
        entity_id: sensor.heating_warmwasser
        below: 60
        above: 48
      - condition: numeric_state
        entity_id: sensor.pv_production_tomorrow
        below: 20
    then:
      - type: turn_on
        device_id: ???
        entity_id: switch.warmwasser_switch
        domain: switch
    else:
      - type: turn_off
        device_id: ???
        entity_id: switch.warmwasser_switch
        domain: switch
mode: single

The following page can be used to calculate the amount of energy required for hot water preparation: Online energy calculator: electricity vs. heat pump

To be able to actively intervene in the control of my heating, I use an ESP32 and a 4-channel relay board, see: Control heating: PV surplus with ESP32 & Home Assistant