Tracer

Tracer is a small service written in Go that enables MQTT for the EPEVER Tracer MPPT Solar Charge Controller.

The goal of the project is to use minimal hardware and be extensible. The repository contains the following binaries, each decoupled using MQTT:

Binary	Description	Role
tracer-controller	Exposes Tracer functionality over MQTT	Required
tracer-api	Exposes Tracer functionality over HTTP	Optional
tracer-app	(To do) Web UI for the API	Optional
tracer-writer	PostgreSQL writer	Optional

Prerequisites

Hardware

RJ45	Top Down	Hat

I'm using the RS485 Serial HAT to communicate with the Tracer MPPT Controller. For instructions on configuring the HAT and setting up the Raspberry PI to use the it, including how to wire RS485 devices, click here.

MQTT

All services communicate using MQTT. At a minimum, this is required to run tracer-controller. Click here for instructions on installing an MQTT server.

PostgreSQL and Grafana

tracer-writer consumes the topic tracer/reading and writes to PostgreSQL when a message is received. The schema for the database is attached at the bottom of this readme. For instructions on installing PostresSQL on Raspberry Pi, click here.

The Grafana Dashboard pictured above is located in the root of the repo as dashboard.json. For instructions on installing Grafana on Raspberry Pi, click here.

Installing

This assumes you are running 64-bit Raspberry Pi OS. If you are using the 32-bit OS, change GOARCH from arm64 to arm in the Makefile. Make sure to also change the RPI_ADDR to the address of your Raspberry Pi on the network.

make # build binaries into ./build
make deploy # copy binaries to /home/pi/tracer/ on you Raspberry Pi

After the files have been copied, systemd unit files can be created:

Create /etc/systemd/system/tracer.api.service:

[Unit]
After=network.target
StartLimitIntervalSec=60
StartLimitBurst=5

[Service]
ExecStart=/home/pi/tracer/api
Restart=on-failure
RestartSec=10

[Install]
WantedBy=multi-user.target

Create /etc/systemd/system/tracer.controller.service:

[Unit]
After=network.target
StartLimitIntervalSec=60
StartLimitBurst=5

[Service]
ExecStart=/home/pi/tracer/controller
Restart=on-failure
RestartSec=10

[Install]
WantedBy=multi-user.target

Create /etc/systemd/system/tracer.writer.service, making sure to change the value to TRACER_DATABASE_DSN to your database DSN:

[Unit]
After=network.target postgresql.service
StartLimitIntervalSec=60
StartLimitBurst=5

[Service]
Environment=TRACER_DATABASE_DSN=postgres://username:password@host:5432/database
ExecStart=/home/pi/tracer/writer
Restart=on-failure
RestartSec=10

[Install]
WantedBy=multi-user.target

Then enable and start the services:

make enable # enable systemd services
make start # start systemd services

Schema

To use tracer-writer, the following table will need to be created:

CREATE TABLE readings(
  id uuid PRIMARY KEY DEFAULT uuid_generate_v4(),
  over_temperature bool NOT NULL,
  day bool NOT NULL,
  solar_voltage NUMERIC(5, 2) NOT NULL,
  solar_current NUMERIC(5, 2) NOT NULL,
  solar_power NUMERIC(8, 2) NOT NULL,
  load_voltage NUMERIC(5, 2) NOT NULL,
  load_current NUMERIC(5, 2) NOT NULL,
  load_power NUMERIC(8, 2) NOT NULL,
  battery_temperature NUMERIC(5, 2) NOT NULL,
  device_temperature NUMERIC(5, 2) NOT NULL,
  battery_soc INTEGER NOT NULL,
  battery_rated_voltage INTEGER NOT NULL,
  maximum_battery_voltage_today NUMERIC(5, 2) NOT NULL,
  minimum_battery_voltage_today NUMERIC(5, 2) NOT NULL,
  consumed_energy_today NUMERIC(8, 2) NOT NULL,
  consumed_energy_month NUMERIC(8, 2) NOT NULL,
  consumed_energy_year NUMERIC(8, 2) NOT NULL,
  consumed_energy_total NUMERIC(8, 2) NOT NULL,
  generated_energy_today NUMERIC(8, 2) NOT NULL,
  generated_energy_month NUMERIC(8, 2) NOT NULL,
  generated_energy_year NUMERIC(8, 2) NOT NULL,
  generated_energy_total NUMERIC(8, 2) NOT NULL,
  battery_voltage NUMERIC(5, 2) NOT NULL,
  battery_current NUMERIC(5, 2) NOT NULL,
  read_duration interval NOT NULL,
  time timestamp NOT NULL
);
CREATE INDEX readings_time_idx ON readings (time);

CREATE TABLE daily_energy(
  id uuid PRIMARY KEY DEFAULT uuid_generate_v4(),
  generated_energy NUMERIC(32, 16) NOT NULL,
  consumed_energy NUMERIC(32, 16) NOT NULL,
  time timestamp NOT NULL
);
CREATE UNIQUE INDEX daily_energy_time_idx ON daily_energy (time);