Octowait

A raspberryPi-powered eInk delay time indicator to minimise cost on Octopus Agile tariffs

This little RaspberryPi project that uses the Octopus Agile tariff API to determine when is the best time to run your high energy tasks. Use it to set the delay timer on your dishwasher, washing machine, tumble dryer, immersion heater etc.

This will save you £100 per year, assuming a daily 4kWh load (washer + dryer + dishwasher), and a reduction in average unit cost of 7p.

1. Assemble the parts

• Inky pHat £20
• Pi ZeroWH (with soldered headers) £30
• 16GB MicroSD £5

2. Install requirements

• Follow standard instructions to get Raspberry Pi OS installed.
• Follow standard instructions to enable wifi: Setting up a Raspberry Pi headless
• Follow standard instructions to enable ssh: SSH (Secure Shell)
• ssh in to your pi
• install the inky code (say no to the additional code): curl https://get.pimoroni.com/inky | bash
• clone this repo into your home folder: git clone https://github.com/simonhearne/octowait.git
• install pip: apt-get install python3-pip
• change dir to the project: cd octowait
• install python dependencies: pip install -r requirements.txt

3. Test run

For convenience, you can make the python file executable: chmod +x run.py. Run the script to see if there are any errors: ./run.py

You can edit the script to change variables such as how long the task is (e.g. a wash might be three hours), what tariff you are on and whether to flip the image. Feel free to play around with the script to change fonts, graph etc!

4. Schedule to run every 15 minutes

Open crontab (you may need to choose your preferred editor): crontab -e Add the following to the end of the file:

*/15 * * * * cd /home/pi/octowait && ./run.py >/dev/null 2>&1

5. Profit

Check the screen when you go to set your dishwasher, washing machine, tumble dryer, slow cooker etc. Set the delay that is recommended, see your energy bills plummet!

If you are not yet on Octopus Agile - use this link to get £50 credit when you switch (plus you get free smart meters & in-home display!) https://share.octopus.energy/jolly-louse-561

6. Save power

If you are running the Pi off a battery, or are just energy conscious, you can run the following commands:

• Disable HDMI output: sudo /opt/vc/bin/tvservice -o
• Disable Bluetooth: echo 'dtoverlay=pi3-disable-bt' >> /boot/config.txt
• Disable LED: echo 'dtparam=act_led_trigger=none' >> /boot/config.txt

You'll need to reboot your Pi for these to have an effect: sudo reboot now

7. Further improvements

• The code assumes that the data from the Agile rates API is in reverse-chronological order
• The graph and suggested delay time are roughly correct, within an hour anyway
• An rPi is over-specified for this simple task, but it is easy to work with. An ESP8266 based board (like the Adafruit Feather HUZZAH with Adafruit eInk Display) would be cheaper and lower power.