System Overview


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The OpenEnergyMonitor system has the capability to monitor electrical energy use / generation, temperature and humidity.

The system is made up of five main units. These can be assembled and configured to work for a variety of applications. The system is fully open-source, both hardware and software. All hardware is based on the Arduino and Raspberry Pi platforms:

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Please select the type of system you are interested in:

  1. Home Energy Monitoring
  2. Solar PV Monitoring
  3. Temperature & Humidity
    Monitoring

The OpenEnergyMonitor system can be used as a simple home energy monitoring system for analyzing real-time power use and daily energy consumption.

The hardware options to set up a home energy monitor are as follows:


emonPi

The emonPi is an all-in-one Raspberry Pi based energy monitoring unit making for a simple installation where Ethernet or WiFi is available at the meter location.

The emonPi can monitor two single-phase AC circuits using clip-on CT sensors. The emonPi can also monitor temperature, and interface directly with utility meters via an optical pulse sensor.

emonPi

  • Raspberry Pi-based energy monitor
  • Local & remote data logging with Emoncms, our open-source web-app for processing, logging and visualising energy and other environmental data, such as humidity and temperature
  • Requires WiFi / Ethernet plus 2 x power outlets
  • Requires pre-built SD card image (included)

Sensors Required:

Power Adapters Required:

View in Shop →



emonTx (optional)

The emonTx is a remote sensor node. Data is transmitted to an emonPi or an emonBase via a low power 433MHz radio.

Note: as an alternative option, the emonTx can be used ‘standalone’ with an ESP8266 WiFi module running EmonESP to post directly to Emoncms without an emonPi / emonBase. See Using the EmonTx v3 with the ESP8266 Huzzah WIFI module

The emonTx can monitor up to four single-phase AC circuits using clip-on CT sensors. A plug-in AC-AC adapter can be used to power the unit and provide an AC voltage sample for real-power calculations. 4x AA batteries can be used to power the emonTx if AC power is not available.

emonTxV3

  • Energy monitoring add-on node
  • Optional add-on if more than two circuits need to be monitored or if WiFi / Ethernet connectivity is not available at the location of the utility meter
  • RF Range is approximately similar to home WiFi and can be affected by obstacles e.g. thick stone walls
  • Up to 2x emonTx can be connected to a single emonPi
  • To connect an emonTx see: Setup > Adding Energy Monitoring Node

An emonTx can be powered by 3 x AA batteries; however, if possible, it is recommended to power the unit with an AC-AC adapter to provide an AC voltage reference for more accurate Real Power and VRMS calculations.

View in Shop →



Optical Utility Meter LED Pulse Sensor (optional)

  • Optional add-on sensor for interfacing directly with utility meters
  • Compatible with all utility meters with LED pulse output
  • Compatible with emonPi & emonTx (one pulse sensor per unit)
  • Reports exact amount of energy (Wh) reported by utility meter
  • Cannot measure instantaneous power
  • Best used in conjunction with clip-on CT sensor(s)

View in Shop →



emonBase (alternative to emonPi)

  • Web connected gateway: Raspberry Pi + RFM69Pi RF receiver board
  • No on-board energy monitoring functions
  • Receive data via low power RF (433Mhz) from emonTx or emonTH
  • Local & Remote Emoncms data logging
  • Runs the same software stack as the emonPi
  • No LCD screen to display local IP address or shut-down button
  • Knowledge of SSH highly desirable
  • Requires pre-built SD card image (optional extra)

View in Shop →


The emonPi and emonTx are designed to monitor single phase AC up to 100A. The system can work for some set-ups in the USA with some changes to the configuration. See user guide section Use in North America.

The emonPi / emonTx have been designed for single-phase AC monitoring. The emonTx can monitor ‘approximate’ 3 phase (assuming balanced phases) using modified firmware and 3x CT sensors + 1 x AC-AC adapter. Further reading


View hardware comparison table


Providing real-time and historic information on your solar generation and demand matching, it will help you make better use of available solar power.

The hardware options to set up a solar PV monitor are as follows:


emonPi

The emonPi is an all-in-one Raspberry Pi based energy monitoring unit making for a simple installation where Ethernet or WiFi is available at the meter location.

The emonPi can monitor two single-phase AC circuits using clip-on CT sensors. The emonPi can also monitor temperature, and interface directly with utility meters via an optical pulse sensor.

emonPi

  • Raspberry Pi-based energy monitor
  • Local & Remote Emoncms data logging
  • Requires WiFi / Ethernet plus 2 x power outlets
  • Single unit required to monitor solar PV, provided the generation and site-consumption feeds are in the same physical location and WiFi/Ethernet connectivity is accessible at this location
  • Requires pre-built SD card image (included)

View in Shop →



emonTx (optional)

The emonTx is a remote sensor node. Data is transmitted to an emonPi or an emonBase via a low power 433MHz radio.

Note: as an alternative option, the emonTx can be used ‘standalone’ with an ESP8266 WiFi module running EmonESP to post directly to Emoncms without an emonPi / emonBase. See Using the EmonTx v3 with the ESP8266 Huzzah WIFI module

The emonTx can monitor up to four single-phase AC circuits using clip-on CT sensors. A plug-in AC-AC adapter can be used to power the unit and provide an AC voltage sample for real-power calculations.

emonTxV3

  • Energy monitoring add-on node
  • Required if solar PV generation and site-consumption feeds are located in separate locations or if WiFi / Ethernet connectivity is not available at utility meter
  • RF range is approximately similar to home WiFi and can be affected by obstacles e.g. thick stone walls
  • Up to 2x emonTx can be connected to a single emonPi
  • To connect an emonTx see: Setup > Adding Energy Monitoring Node

An emonTx can be powered by 3 x AA batteries, however this is not recommended for solar PV monitoring application since sensor adapter is require to determine direction of current flow and accurate VRMS & Real Power calculations.

Sensors Required:

Power Adapters Required:

View in Shop →



Optical Utility Meter LED Pulse Sensor (optional)

  • Optional add-on sensor for interfacing directly with utility meters
  • Compatible with all utility meters with LED pulse output
  • Compatible with emonPi & emonTx (one pulse sensor per unit)
  • Reports exact amount of energy (Wh) reported by utility meter
  • Cannot measure instantaneous power
  • Best used in conjunction with clip-on CT sensor(s)

View in Shop →



emonBase (alternative to emonPi)

  • Web connected gateway: Raspberry Pi + RFM69Pi RF receiver board
  • No on-board energy monitoring functions
  • Receive data via low power RF (433Mhz) from emonTx or emonTH
  • Local & Remote Emoncms data logging
  • Runs the same software stack as the emonPi
  • No LCD screen to display local IP address or shut-down button
  • Knowledge of SSH highly desirable
  • Requires pre-built SD card image (optional extra)

View in Shop →



The emonPi and emonTx are designed to monitor single phase AC up to 100A. The system can work for some set-ups in the USA with some changes to the configuration. See user guide section Use in North America.

The emonPi / emonTx have been designed for single-phase AC monitoring. The emonTx can monitor ‘approximate’ 3 phase (assuming balanced phases) using modified firmware and 3x CT sensors + 1 x AC-AC adapter. Further reading


View hardware comparison table

3. Temperature & Humidity Monitoring

Temperature monitoring example

The hardware options to monitor temperature and/or humidity are as follows:


a) Wireless Temperature Hardware

emonTH

The emonTH is a long battery-life, easy to deploy, wireless room temperature and humidity sensor node designed for monitoring a building’s thermal performance.

The emonTH is powered by two AA batteries and has an on-board Si7021 temperature and humidity sensor. An external DS18B20 temperature sensor can easily be connected to a screw terminal block to provide external temperature readings.

emonTH

  • Wireless temperature & humidity monitoring node
  • Compatible with emonPi & emonBase
  • 6 month battery life (2 x AA batteries not included)
  • Up to 4 emonTH nodes can communicate with a single emonPi
  • Internal temperature & humidity + optional external probe
  • Optional pulse sensor input

View in Store →



b) Wired Temperature Hardware

DS18B20 sensor on RJ45

  • Compatible with emonPi & emonTx
  • Up to 6 sensors can be connected to a single emonPi / emonTx using RJ45 Breakout
  • Sensor wire can be extended using RJ45 cable and RJ45 Extender

View in Shop →


DS18B20 sensor on wire

  • Compatible with emonTx terminal block
  • Compatible with emonPi using RJ45 Breakout
  • Up to 6 sensors can be connected to emonPi / emonTx using RJ45 Breakout

View in Shop →


View hardware comparison table


  emonPi emonBase emonTx emonTH
Main purpose All-in-one monitor & gateway Web-connected gateway Energy monitor add-on Sensor Node
No. CT sensor inputs 2 0 4 0
No. of voltage sensor inputs 1 0 1 0
No. of pulse counting inputs 1 - via RJ45 0 1 - via RJ45 1 - via terminal block*
No. of temperature sensor inputs 6 - via RJ45** 0 6 - via RJ45** 2 - internal + external
No. of humidity sensor inputs 0 0 0 1
Power supply 5V USB mini-B 5V mico USB 9V AC-AC / 3 x AAA 2 x AA
Local data storage (Emoncms) Yes Yes No No
Requires additional base-station No No Yes Yes
LCD Display Yes No No No

* Requires manual wiring into terminal block

* Requires RJ45 breakout board

Full Documentation on all hardware units in the Technical Resources section.


Video Guide


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