A Solar Panel battery charging monitor using a Raspberry Pi 2 connected to a Maximum Power Point Tracker (MPPT) and a Raspberry Pi 3 showing the output graphs and data.

I'm setting up an off-grid solar solution and the MPPT controller I purchased only supports modbus via serial. Had I spent an extra $200, I could have got the next model up to have a RJ-45 port, web interface and SNMP features but maybe down the road I will upgrade. It all started with a co-worker recommending Cacti and I have now decided to expand that to include a separate full display console as well and have everything run off solar power.



  • Raspberry Pi 2 Model B  - This is my Cacti Server connected to the MPPT controller
  • Raspberry Pi 3 Model B - This is my display board console for graph display mounted next to my Inverter Panel.
  • Element 14: 4DPi-24-HAT - Raspberry Pi 2.4in QVGA Touchscreen LCD Hat Module
  • DROK DC-DC Volt Buck Converter 8-50V 12V24V36V to 5V 3A (currently on order)
  • Serial to USB cable
  • TriStar MPPT TS-45 solar controller


  • Raspbian Jessie with PIXEL
  • Cacti 0.8.8b
  • Cacti Plug-in Cycle-v2.3-1
  • Libraries  & software for modbus


Additional Notes:

Cacti was chosen to allow long term solar & charging stats to be saved into a database and viewed by built in graphs available.

My Cacti Pi Server is setup on Pi 2 (for low power requirements) and currently graphing default stats (CPU, RAM, etc.) for now.

My "Pi Display console" will be a dedicated display to cycle through the graphs with data received from my MPPT controller

Edits to Cycle plug-in PHP files are required to fit the graph nicely on 2.4 inch LCD

I added entry into ~/.config/lxsession/LXDE-pi/autostart to have chromium load full screen in kiosk mode

I also picked up a 7800 mAh battery pack to allow my Pi 3 with 2.4 LCD touch screen to be fully mobile, leveraging the wireless functionality.

Next stage: Currently working on getting the MPPT controller setup. Then installation of Libmodbus on Raspberry pi

 Raspberry PI 3 running Cycle plugin for cacti - Ryan Wolfe

Project by: Ryan



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