Elecricity spot price display using NodeMCU and e-paper

Or an “is this a good time to do laundry at 90°C” machine.

Displays current hourly electricity price as text and hourly prices for up to 48h as graph. Higher prices are shown with configurable gradient from black to red.

Ingredients

• NodeMCU module
  • pretty much any ESP8266 module with 4MB flash or more should also work
• WeAct 2.9″ red-black-white e-paper display module
• Home Assistant and Nord Pool integration

Preparation

1. connect e-paper module to ESP8266 module
   • pin assignments are in epaper-electricity-price.yaml under spi and display
   • connect power pins to NodeMCU's 3V and G pins
2. install ESPHome
3. create secrets.yaml and add values for all !secret references in the main yaml file
4. download the font Arial from wherever (it's copyrighted), and put arial.ttf, arialn.ttf, and arialnb.ttf in this directory
5. build and flash: esphome run epaper-electricity-price.yaml
6. add the Home Assistant automation in homeassistant-automation.yaml
   • it can be copy-pasted to Home Assistant's web interface
7. adjust settings in Home Assistant device configuration screen

If the display is sometimes garbled, install a 0.1 µF decoupling capacitor between VCC and GND on the e-paper module.