emonPi2: 6-Channel Energy Monitor

£225.88 (Inc. VAT)
£188.23 (Ex. VAT)
170.00 Grams
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The emonPi2 is a 6 CT channel as standard (12 CT channel with expansion board) electricity monitor with an integrated Raspberry Pi, capable of single phase or 3-phase monitoring.

Supports wired temperature sensing & pulse counting. Can be used as a base-station for further sensor nodes such as the emonTx5 and emonTH2.

Supports full local or remote data logging and visualisation capability via Emoncms.

Perfect for monitoring home electricity, solar, storage, heat pumps and electric vehicle charging or any AC electricity circuit for that matter.

emonPi2 features:

Measurement board:

  • 6x clip-on CT current sensor inputs (suitable for a range of 333mV voltage output CT sensors)
  • Expandable to 12 CT channels with the expansion board (Pi Zero 2W option only)
  • Voltage input for use with emonVs precision voltage sensor (RJ45 connector)
  • Full Real/Active power measurement & continuous sampling
  • Cumulative energy persisted on reboot
  • Single phase, 3-phase (4-wire) and N.American split phase support.
  • Optional pulse counting and analogue voltage input
  • On-board USB-C to UART converter for easier programming and serial output
  • Handled by the Pi: DS18B20 temperature sensing (pluggable terminal blocks required)
  • Handled by the Pi: 433 MHz RFM69CW radio transceiver

Integrated base-station:

  • Raspberry Pi mini computer
  • Full local data logging and visualisation capability using emoncms.
  • Option to post data to a remote server such as emoncms.org
  • Data accessible via MQTT
  • Software support for reading from Modbus & M-BUS meters via USB
    (Please select RaspberryPi 4 for externally accessible USB ports)


  • Wall-mount aluminium enclosure
  • Made in UK
  • UKCA & CE approved

Sensor selection guide:

1. emonVs voltage sensor and power supply selection

The emonPi2 is designed for use with the emonVS precision voltage sensor and integrated power supply which provides higher accuracy voltage and active power measurement alongside a single socket or hardwired install.

A single phase emonVs with UK plug is selected by default above. Please change to suit your application.

  • The N.American split phase option uses the 3-phase emonVs with phase 1 & 2 used for the split phases.
  • Please enquire for 3-phase 3-wire systems.
  • Shared: If you already have an emonVs in the same location it is possible to share the emonVs between multiple units with an emonVs RJ45 Duplicator
  • Current only: The emonPi2 can be used without an emonVs in current only mode. This is only supported by the 6 channel firmware.

For separate product entries, please see: 1-phase emonVs (UK Plug, EU Plug, No Plug) and 3-phase/split phase emonVs.

2. Optional: 6 channel expansion board

Expand the number of CT current channels from 6 to 12 with an expansion board.
We will fit this expansion board for you if selected above.
Separate product entry: EmonPi2 6 CT Expansion board

3. CT current sensor selection

To obtain the highest accuracy we recommend choosing CT current sensors that match the current rating of the circuit being measured. 

E.g for 16A or 20A circuits choose the 20A CT sensor, for 32A or 40A circuits choose the 50A CT sensor and so on. No damage will be done if the current in the circuit exceeds the CT rating, the output will just be 'clipped' resulting in inaccuracy.

The physical size of the CT sensors is also proportional to the current rating which makes the smaller sensors very suitable for installation inside fuseboxes / consumer units.  See individual CT current sensor product pages for more information:

Note: The emonTx5 & emonPi2 both require voltage output CT sensors, the old current output YHDC (blue) 100 A CT sensor is NOT compatible.

4. Temperature sensing

The emonPi2 has full DS18B20 temperature sensing support. Temperature sensing is handled by the RaspberryPi directly.
Temperature sensors can be connected to 2x 3-pin pluggable terminal blocks, while there is not a specific limit on the number of sensors that can be connected we have tested up to 6 sensors at any one time.

5. Pulse counting.


There are a couple of things to consider when combining the emonPi2 with an existing system.

  • emonTx4 + RJ11 emonVs + emonBase: The emonPi2 can be used to replace an existing emonBase in this configuration. An adaptation is required to the original emonVs voltage sensor to provide the RJ45 voltage sensor output that the emonPi2 required. It's possible to either send the original emonVs back to us and we can make that modification for you in our office or we can send a pre-prepared cable if you are happy to make this modification yourself. See this forum post for more detail and let us know if you need the pre-prepared cable in the order comment form.
  • emonTx4 running compatibility firmware: The emonPi2 only supports the new LowPowerLabs encrypted radio format. Any existing radio nodes running JeeLib classic radio format will need updating to the LowPowerLabs format to be received by the emonPi2 integrated radio.
  • Replacing an emonPi v1: The emonPi2 can replace an emonPi v1, again any radio nodes running the JeeLib classic radio format will need updating to the LowPowerLabs format. The emonPi 1 AC-AC adapter voltage sensor and YHDC 100A CT sensors are not compatible as standard with the emonPi2. 


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