dreadpi

Demand Response Enabling Device (DRED) for Raspberry Pi.

Dreadpi enables automatic control of air conditioning DRM modes based on your current renewable power generation. It achieves this by controlling a relay board connected to the RasPi GPIO pins. This can reduce your grid energy consumption by better aligning your peak load with your peak generation.

DRED is an AU/NZ standard (AS/NZS 4755).

Supported collectors:

• api.enphaseenergy.com (enlighten)
• pvoutput.org
• standalone script

Requirements

• RasPi hardware (you'll be error-bombed if dreadpi can't access the broadcom chip).
• Dual Double Throw Relay module ($3 online) and leads ($1 online).
• Root access (for controlling the broadcom chip).
• Python 3.x.
• RPi.GPIO Python 3 module (raspbian package "python3-rpi.gpio").

Install

Install to ./dreadpi/:

git clone https://github.com/robdevops/dreadpi.git

Test

sudo ./dreadpi/dreadpi.py

Config

At minimum, a data source must be confgured. You'll need to obtain API keys and replace XXX values for the API collectors to work, but you can test with the default 'external_script' setting.

dreadpi.cfg

Schedule

Creating an example cron which captures the last output to a file:

# Note: Running this too often will shorten the relay life
echo "*/15 5-21 * * *     root    /root/dreadpi/dreadpi.py > /var/log/dreadpi.cron.lastrun 2>&1" > /etc/cron.d/dreadpi

Logging

Critical errors:

/var/log/dreadpi.errorlog.txt

DRM states (for graphing purposes, states are expressed as a % of max energy use):

/var/log/dreadpi.plotlog.txt

Security

Because controlling the RasPi GPIO pins requires root access, the following restrictions have been implemented:

• Dreadpi runs all its collectors as the 'nobody' user.
• The external_script filename can not contain most special shell characters.
• Online APIs use hard coded URL prefixes.

Because API keys are read/write, and the API data itself is a potential privacy concern, your config should not be world readable (and obviously not world writeable):

sudo chmod 600 dreadpi/dreadpi.cfg

Wiring

Disclaimer: This info is provided for educational purposes. Don't mess around with mains voltage appliances; they're dangerous. Your safety is your own responsibility. Take proper precautions.

Jumper:

• Remove the relay module jumper closing JD-VCC and VCC.

RasPi to relay (control pins):

• PIN1 (3V3) -> VCC
• PIN2 (5V) -> JD-VCC
• PIN6 (GND) -> GND
• PIN11 (GPIO17) -> IN1
• PIN13 (GPIO27) -> IN2
• PIN9 (GND) -> GND (redundant)

Relay to DRM (switch pins):

• RLA1-COM -> DRM-COM
• RLA2-COM -> RLA1-NC
• RLA1-NO -> DRM2
• RLA2-NO -> DRM3
• RLA2-NC -> (none) rest position, informally "drm0".

Contribute

You can easily add new collectors. Incidentally, the PVOutput documentation provides many third party code examples for accessing various smart invertors: http://pvoutput.org/help.html#integration-contributed-software

To integrate with dredPi, just drop a .py in the lib directory and have it return a value in watts. Load it from energy.py like this:

from lib import <your collector>

And call it like this:

elif DATA_SOURCE == "<your collector>":
    watts = <your collector>.<your function>()

To be accepted upstream, also:

• Pass your user configuration from dreadpi.cfg:

elif DATA_SOURCE == "<your collector>":
    watts = <your collector>.<your function>(USER, KEY, SYSID)

• Copy/Paste the logging block from another collector (requires import logging and import os).

Ideally your collector would also:

• Return a POSIX content timestamp:

elif DATA_SOURCE == "<your collector>":
    watts, content_timestamp = <your collector>.<your function>(USER, KEY, SYSID)

• Perform exception handling and health warnings as per existing examples.
• Have well commented code.

Note: collectors must be able to run as 'nobody'.

This was my first ever attempt at Python. I welcome suggestions on how to do anything more elegantly, no matter how trivial. Just log an issue or DM me. Thanks and happy hacking!