M5StackSolar2MQTT

measure solar panel voltage and current on M5Stack, transmit via MQTT to Node Red

Hardware / BOM

Solar Panel with Controller (and USB output) - output current must not exceed 4A
M5Stack
Voltmeter Unit (ADS1115)
Ammeter Unit (ADS1115)
Grove-T Connector
Grove Cable

High-Level flow

Solar panel
- Ammeter wired in line between solar panel and controller
- Voltmeter wired in parallel to the solar panel
Solar Controller
- M5Stack plugged into USB output of solar controller
M5Stack
- connect to Wifi & MQTT
- measure voltage and current every couple of seconds and display on screen
- transmit via MQTT every 20 seconds as a JSON object on topic "SolarPanel"
Node-Red
- receive and parse the JSON object on topic "SolarPanel"
- calculate power and convert units
- upload resulting data to InfluxDB
Grafana
- load data from InfluxDB and display it

Installation

Install and configure
- Node-Red plus this node:
  - node-red-contrib-influxdb
- InfluxDB
- Grafana
- I used DietPi to conveniently install all on a Raspberry Pi
Create a database in InfluxDB
Import M5Stack project to UIFlow, adjust your MQTT details and upload to M5Stack
Import Flow to Node-Red, configure MQTT and InfluxDB details and deploy
Import Panel to Grafana and configure InfluxDB details

Images