MQTT based Solar Data Logger and Usage Automation

This is adopted from MQTT-C reconnect_subscriber example, using the MQTT-C library: https://github.com/LiamBindle/MQTT-C

The data source is emonCMS: https://github.com/emoncms/emoncms But could be any MQTT source.

This is what's contained in this repository:

• solar-mqtt.c : Data logging and electricity usage automation on Raspberry Pi
• www : Website files for viewing the data logs with graphical representation
• pc.c : Runs on PC to automatically control BOINC according to electricity usage

Requirements for solar-mqtt.c:

• MQTT source, publishing solar generation, export and usage
  • Broker needs to allow_anonymous, edit /etc/mosquitto/mosquitto.conf
• Raspberry Pi (I used on version 3B and 4B, should work with all)
• Setup a RAMdisk at /var/ramdisk (https://www.domoticz.com/wiki/Setting_up_a_RAM_drive_on_Raspberry_Pi)
• Pimote and plugs from Energenie (see pc.c on how to comment out this part if you only want data logging)
• wiringPi library for RaspberryPi GPIO interactions (not needed for data logging)

Requirements for Raspbian Linux distro:

• Install lighttpd and php-cgi (sudo apt install)
• Create symbolic links as detailed in LINKS.txt
• Install the systemd file to start the program and manage RAMdisk
• For Raspberry Pi 4, install latest wiringPi: sudo dpkg -i wiringpi-252.deb (at time of writing, apt repo version is 2.50... http://wiringpi.com/wiringpi-updated-to-2-52-for-the-raspberry-pi-4b/)

The dataflow for solar-mqtt.c and www parts on Raspberry Pi:

1. Raspberry Pi is connected to my home network and subscribe to broker.
2. MQTT message on the home network every 30 seconds it gets a new reading.
3. There is a listener program always running on RPi (the compiled solar-mqtt.c)
4. The subscriber program in RPi captures the broadcast and does 2 things:
   a. Decides whether there is any export and turns on Pimote sockets and send WakeOnLan PC
   b. Records its state and current usage/generation/export information into a file on RAMdisk (/var/ramdisk)
5. Use any web browser navigate to RaspberryPi and see a graph and log files (/var/www)
6. At night, a bash script is run to archive the log file and trim the live log file if it's too big (solarlog-save.sh) Log files are archived at /home/pi/solar/log

A few things to note:

• The current log file will disappear if RPi power is interrupted. Use "sudo halt" command to safely shutdown RPi
• On RPi, there should be the following:
  • 1 systemd using solarlog-persist.service, which ensures log is persistent when shutdown gracefully and launches the subscriber C program
  • 1 scheduled tasks: solarlog-save.sh at 23:59
• To build solar-mqtt.c, use comp.sh script
• To build pc.c, no special command is needed, Linux or Cygwin environment recommended.
• Inside LINKS.TXT details the links required for the graph webpage
• The definition for log file columns are found near the end of C files, see printf commands
• Attempt has been made to keep similarity between the C files so that the updates and bug fixes can be applied to both easily.