House Brain

Manages hot water heating, solar PV generation, and battery management via a Sofar ME3000 inverter.

Hardware

• epaper display https://www.waveshare.com/wiki/E-Paper_Driver_HAT
• 5 tank temp sensors (from top to bottom)
• gas heating inlet and outlet sensor
• cold water tank temp sensor
• relay to switch between upper and lower immersion element
• relay to call for boiler heat

Interface

• Button to call or cancel gas heat
• Another button - perhaps to display more details on the display

Display

Display lists the following information

• Number of liters of hot water

This will be calculated using the tank sensors, and incoming water temperature

• Status of electric heating
• • Number of watts going into the tank
• • Indicate which element is active
• • Number of kWh so far today
• Status of gas heating
• • Minutes of heating
• • Inlet outlet temps

System events

• Incoming sofar MQTT reading
• Periodic display refresh
• Heat button press
• Other button press

System routines

Gas heating

Closes relay to call for boiler heat. Stops call for heat on any of the following conditions.

• Heating inlet and outlet temps are similar and hot - this means the water is no longer being heated
• The tank is at the desired temp (60c?)
• A fixed duration of time passes
• The call button was pressed again

Immersion management

• Records when current is flowing to the elements. We need this to calculate the total number of kWh sent to the tank.
• Manages the switch between the top element to the bottom element once current is no longer detected to be flowing to the top element.
• • If current does not flow to the bottom element we will switch back to the top element because we may be in either of the following conditions
• • 1. The whole tank is 70c or above
• • 2. There is no excess power available to power either immersion
• • If power is flowing to the bottom element, periodically test if current will flow to the top element again, as it may have cooled.

Architecture

Each component of the solution will run inside a docker container

e-paper display docker image

A python web service, that uses pillow to render images to the e-paper display. The web service will accept images.

postgress db

The database that records the following information

1. Sofar inverter readings (MQTT)
2. Temp sensor readings
3. Immersion current readings
4. Logs

The service

• Receives MQTT messages from the ESP32 on the sofar inverter.
• Renders the e-paper display image
• Manages periodic and event based tasks.
• Probably serves the same information via a react app