A raspberry-pi based webserver to display live updating power usage graphs.
Incoming data is read through the P1 port over a RJ12 cable, following the P1 companion standard of the Dutch Smart Meter Requirements, also used in Belgium.
A bit of breadboard circuitry is used to match the 5V levels of the P1 port to the 3.3V levels of the Raspberry Pi:
- a simple resistive voltage divider to lower the data signals
- two sequential inverters built from transistor to raise the control signal
Data is stored long-term in a SQLite database, and displayed in a web interface using Plotly.js.
The main page shows graphs of for different time ranges (last minute, hour, day, week), and a dedicated custom page allows the user to select a custom time period and resolution to display. Data from this custom time range can be downloaded as a csv file.
Main page with default plots:
Custom time range and download page:
Meter connection:
Raspberry pi and breadboard setup:
Breadboard closeup, with status leds for power (red), enable (green) and data (blue):
