Prometheus exposition

Prometheus is an event monitoring and alerting system, based on a time series database. It is commonly used to monitor IT-systems such as servers and the applications they run. If enabled through prometheus → enable in the configuration, RctMon exposes its internal state, ready to be scraped by one or more Prometheus servers. For a nice graphical representation of the collected data, Grafana is recommended.

Configuration

If enabled, the endpoint can be configured using prometheus → bind_address and prometheus → bind_port. For example, to make them accessible from the same machine only, specify 127.0.0.1 or localhost for bind_address. The port can also be changed from the default, by setting bind_port to (for example) 8080. The combination will make the metrics available at http://localhost:8080/metrics.

In addition to that, if both prometheus → enable and prometheus → exposition are enabled, the readings from the inverter will be available here, too. The values are cached internally, as the inverters responses are too slow for live readings. This in turn allows for redundant scraping from multiple Prometheus servers at high frequency without affecting the inverter in any way.

Prometheus configuration

In prometheus.yml (usually in /etc/prometheus/), add the endpoint to the scrape_config, for example like so:

scrape_configs:
  - job_name: rctmon
    static_configs:
      - targets:
          - localhost:8080

The default place for metrics is /metrics, thus specifying the host and port is enough. Note that the exposition does not support TLS encryption or any form of authentication and adding that is not planed. If required, configure a reverse proxy such as HAProxy, Nginx or Apache.

InfluxDB configuration

InfluxDB 2.x is able to scrape Prometheus endpoints. This may be useful for monitoring the application state with InfluxDB rather than Prometheus. It doesn't make sense to enable prometheus → exposition in this case as the application can push the inverter metrics to InfluxDB just fine.

Please refer to the Manage scrapers section in the InfluxDB manual.

Application metrics / monitoring

The metrics meant for monitoring the application are always present when the Prometheus endpoint is active. Some of them stem from the default python and process exporter built into the library that is used to create the endpoint. They start with python_ and process_ and are usually of low interest.

All metrics from RctMon start with the string rctmon_. Due to the design of the library, for each metric an additional metric is created, ending in _created. This is due to the OpenMetrics format supported by the library and can't be deactivated.

As of version 0.0.1, the following metrics are exposed:

Name	Type	Description
rctmon_bytes_received_total	Gauge	Amount of bytes received from the inverter since start of the program
rctmon_bytes_sent_total	Gauge	Amount of bytes sent to the inverter since the start of the program
rctmon_decode_error_total	Gauge	Amount of errors that occured during parsing and decoding responses from the inverter. The kind label can be crc for CRC checksum mismatches, command for when the command byte was invalid and the frame couldn't be parsed, payload when the frame was received correctly but the data it carried was invalid, and length indicating that the parser overshot the end of the frame and the frame was dropped.
rctmon_device_up	Gauge	Shows if the connection to the inverter is up (1) or not (0).
rctmon_frames_received_total	Gauge	Amount of frames received since the start of the program (not including decode errors)
rctmon_frames_sent_total	Gauge	Amount of frames sent since the start of the program.
rctmon_info	Info	Information about the program, such as its version.

Inverter metrics

These become available if prometheus → exposition is enabled. It may take a moment after program start for them to appear as the inventory of the inverter needs to be queried before the values can be requested from it.

They all have a label inverter which contains the name of the inverter. This is the same name as shown in the smartphone app made by RCT (internally called android_description).

Percentages are generally in the range 0.0 to 1.0.

Warning

RctMon is still in development, individual metrics may be added, removed or renamed without prior notice!

Name	Description
rctmon_inventory	A component label shows that a component was detected, such as generator_a and generator_b for the solar strings or power_switch for the Power Switch component.
rctmon_inverter_grid_separated	Shows info about island mode status. If value is 1 inverter is in island mode.
rctmon_inverter_info	Shows static info such as the control_software_version, the serial_number and parameter_file.
rctmon_generator_voltage_volt	Voltage, label generator is a or b.
rctmon_generator_power_watt	Watt, label generator (a, b).
rctmon_generator_mpp_target_voltage_volt	MPP target voltage, label generator (a, b).
rctmon_generator_mpp_search_step_volt	MPP search step, label generator (a, b).
rctmon_temperature	Component temperature for builtin components
rctmon_household_load	Household load over all phases
rctmon_household_load_phase	Single-phase load, label phase is l1 to l3.
rctmon_grid_power_watt	Grid power, label phase is l1 to l3.
rctmon_grid_voltage_volt	Grid voltage, label phase is l1 to l3.
rctmon_grid_voltage_phase_to_phase_volt	Phase-to-phase voltage
rctmon_powerswitch_info	Information about the Power Switch component if detected, such as the bootloader_version and software_version
rctmon_grid_voltage_volt	Grid voltage, phase is l1 to l3.
rctmon_grid_frequency_hertz	Grid frequency, phase is l1 to l3.
rctmon_powerstorage_frequency_hertz	Inverter frequency if active, phase is l1 to l3.
rctmon_bms_info	Information about the BMS if detected, serial_number
rctmon_battery_state_of_charge_min_percent	Battery, minimum soc
rctmon_battery_voltage	Battery voltage
rctmon_battery_power	Battery power
rctmon_battery_state	Battery state (state machine position)
rctmon_battery_state_of_charge_percent	Battery SOC
rctmon_battery_state_of_charge_target_percent	Battery target SOC
rctmon_battery_state_of_health_percent	Battery health
rctmon_battery_temperature	Battery temperature
rctmon_battery_bat_status	Battery status
rctmon_battery_impedance_fine	Battery impedance
rctmon_battery_discharge_amp_hours_total	Total amount of discharged energy
rctmon_battery_stored_energy_total	Total amount of charged energy
rctmon_battery_state_of_charge_min_percent