1. Mounting
  2. Wiring
  3. CT Sensor Installation
  4. Advanced Installation Options
  5. Relay & Sensor Board
  6. Fitting the Cover
  7. Setup

1. Mounting

–   eddi is NOT suitable for installation outdoors.

–   Ensure the device always has adequate ventilation; do not block the vents or obstruct the airflow at the back of the unit.

–    eddi must be fixed to a vertical surface

The eddi needs to be securely mounted to a wall using the dedicated mounting bracket which comes attached to the unit.


1. With the unit on its back on a flat surface, remove the front cover by unscrewing the two screws  and lifting it off.
2. Loosen the two mounting bracket securing screwsand separate the bracketfrom the eddi.
3. Offer the bracket up to the wall and mark the holes for drilling. If fixing to a timber stud wall, you can use the two central vertically aligned fixing points to screw the bracket directly into the timber.


2. Wiring


WARNING! An electric shock can be fatal; electrical connection work may only be carried out by a competent person

The earth conductor must be correctly installed and reliably connected

This device must be equipped with an over-current protection device of maximum 16 Amps (B16)

Only purely resistive loads must be connected to the Heater output terminals


Strip Length


Overview Diagram

The diagram below gives an overview of the basic wiring with respect to the grid supply and the microgeneration system.

Also refer to the Application Examples for full wiring schematics.




The eddi device should be connected to a single-phase 230V or 240V nominal AC supply. The supply should be from a dedicated 16A circuit breaker, or it can be from a hard-wired 13A fused spur outlet if the heater load is less than 3kW.

Heater Loads

Most purely resistive heaters can be used with eddi, examples include immersion heaters, storage heaters, convection heaters and underfloor heating mats. Refer to the Application and Examples section for wiring diagrams using different heater types. Whichever heater type is used, the following criteria must always be observed:

–   One or two purely resistive loads may be connected (Note: only one is live at any one time)

–   Maximum rating of each load is 3.68kW

–   Minimum heater rating is 150W

–   Resistive loads only

–   Heater Neutral conductor must be connected to heater output N terminal

–   No electronic controls to be connected to Heater terminals; mechanical thermostats only

–   No timers to be connected to Heater terminals, including mechanical timers

Cable Clamps

If using flexible cables or cables not secured by other means, the cable clamps must be used to secure the supply and heater cables.

3. CT Sensor Installation

Current Transformers (CTs) are used to measure current at various places of the installation. For example, the Grid connection point, the solar/wind inverter or a static battery system.

Installation of a CT to monitor the Grid connection point is required. Other CTs are optional and can be purchased separately. The number and location of CTs used within an installation will vary according to devices installed and the user requirements.

CTs can be wired to any myenergi device with CT inputs (e.g. eddi, zappi or harvi). This enables very flexible installation as the CT can be wired to the nearest device.

Note: The harvi device can be used if it is not practical to connect any CT to the eddi or zappi.

Once installed the CTs need to be configured, see CT Config for details of how to configure the CTs.

Grid CT

The Grid CT sensor (supplied) needs to be clipped around either the Live or Neutral meter tail of the electricity supply meter. If using the Neutral conductor, reverse the direction of the sensor (so the arrow is reversed).

The positioning of the Grid CT sensor is crucial, take note of the following when deciding where best to install the sensor:


Can be connected to any myenergi device with a CT input e.g. the eddi or zappi (wired sensor) or harvi (wireless sensor).
ALL of the import and exported power must be ‘seen’ by the sensor – be sure to install it upstream of ANY junction box or ‘Henley Block’ (the CT can be fitted inside the consumer unit).
There must be only one Grid CT per-phase for the whole installation. (There can be other CTs but only one at the grid connection point, also note CTs for third-party devices do not matter).
The CT should be on the Live or Neutral cable.
The arrow on the bottom of the CT sensor must be pointing towards the consumer unit (in the direction of grid import) if on the Live cable, or reversed if on the Neutral cable.
Ensure the CT is fully closed and clicks shut.
Be sure to wire the CT the correct way round; black [–], red [+] otherwise import and export readings will be swapped.



Additional CTs

There is an option to add other CT sensors (available separately) for monitoring the generation or other appliances such as battery systems or general loads. Installing a CT for the generator (PV system) will allow the main screen to show the generated power and the total power consumption of the all the other appliances in the property.

CTs can also be used to limit the power drawn form the supply. See Load Balancing / Current Limiting.


Additional CTs Can be connected to any myenergi device with a CT input that is linked to the network see Linking Devices.
The arrow on the bottom of the sensor must be pointing in the direction of normal power flow (e.g. away from the PV inverter) if on the Live cable or reversed if on the Neutral cable.
Ensure the sensor is fully closed and clicks shut.
Be sure to wire the CT the correct way round; black [–], red [+].


Extending the CT sensor cable

If there is a need to extend the CT sensor cable, twisted-pair cable like CAT5 or telephone cable must be used (only use one pair). DO NOT use mains cable, bell wire or speaker cable. It is important to use only twisted-pair cable to maintain signal integrity. The cable can be extended up to 100m.

Wireless CT Sensor (optional accessory)

In some cases it can be difficult or impractical to install a wired sensor. For example it may be the case that the eddi unit needs to be connected to a sub-board, rather than main consumer unit and two consumer units are in different buildings.

The solution

is to install harvi – a clever little device that enables the zappi and eddi products to be installed without using wired CT sensors for measuring the grid and/or generation power; instead the CT sensor is connected to harvi.

The harvi does not need batteries or a power supply – the energy from the sensor is harvested and used to transmit the measurement signal to the zappi or eddi. This means batteries or electrical wiring are eliminated!

Up to 3 CT sensors may be used with harvi and it also supports 3-phase systems if three sensors are connected.

Refer to the harvi installation guide for details on installing and configuring harvi for your system.

CT Golden Rules

Grid CT

–    Only ONE Grid CT per phase (check for only one ~ symbol in Linked Devices Info).

–   Located to ‘see’ ALL import and ALL export current (i.e. always upstream of any junction box).

–   Arrow pointing in direction of import (e.g. towards consumer unit if on Live cable).

–    Must be on the same phase as the Master myenergi device.


All other CTs

–    Arrow should point towards the consumer unit.


3 Phase harvi CTs

–   When using harvi in 3-phase mode, the CT inputs correspond to the phase number (e.g. CT1 = Phase 1).


CT can dos


Can be wired to ANY myenergi device in the network.
harvi can be used to make ANY CT wireless.
Cable can be extended up to 100m (must use twisted-pair cable e.g. one pair of CAT5).
Cable can be shortened.
Can be clipped around two or more conductors feeding appliances of the same type (e.g. two Live cables from two inverters that are on the same phase).
Can be in close proximity to other CTs.
Wires can be swapped around in device to reverse the direction of the readings (e.g. change import to export).
Can be grouped with other CTs of the same type so that the power reading is summed (e.g. east and west solar Generation).
Can be used on the Neutral conductor (direction of arrow or wires must be reversed).
Can be set to None if you want to exclude the reading.

4. Advanced Installation Options

Load Balancing / Current Limiting

CTs can be also used to the limit current drawn by myenergi devices to avoid overloading circuits. this is sometimes referred to as load balancing. There are four different ways to limit current and they can be used alone or combined for more complex situations. See the table below:


Function Operation Example
Device Limit Sets a maximum current that can be drawn by the device (e.g. eddi). The current will not be exceeded even during boost. An eddi is wired to a 3.4kW heater, but the supply to the eddi is only a 13A fused spur.
Grid Limit Sets the limit that can be drawn from the grid connection (i.e. the maximum import current). The eddi and any other linked myenergi device, will limit the current they draw if there is a danger of exceeding the set Grid Limit. An eddi is installed in a property with a 65A main fuse. The property has a 10kW electric shower and a washing machine (2.5kW).
With the Grid Limit set to say 55A, the eddi would reduce its load if the shower and washing machine were on at the same time.
Group Limit

(internal CT)

Sets the combined current limit for several myenergi devices. A property has a large PV array and a swimming pool, three eddi units are installed to heat the pool with surplus solar power using 3kW heaters. The supply for the eddi units is only 40A, to be safe a Group Limit of 35A is set.
Group Limit

(with external CT)

Sets the combined current limit for several myenergi devices that are sharing a supply with another large appliance. An eddi is installed to heat the hot water cylinder in a garage which also has a washer and a dryer (2.5kW each), the garage has a supply of only 32A coming from the main consumer unit in the house. If all appliances were on and there was no limiting set, the total current would exceed the maximum supply current.

Three-Phase Systems

If the installation supply is three-phase, it is recommend to install a harvi device and use three Grid CTs (one for each phase). This will allow the eddi to show the total grid import and export figures rather than just one of the phases.

If all three phases are monitored and the generation is 3-phase, it is also possible to net the export power across phases, to do this, enable Net Phases in the Supply Grid menu – see Supply Grid – Net Phases. This allows the eddi to use surplus power from any phase and not just the phase which the eddi is installed on. However, you must be sure that the electricity is metered in such a way as to allow this.

Three eddi units can be installed (one per phase) provided there are suitable loads.


Tip: It is usually possible to split a 3-phase heating element into 3 individual elements by removing the links.

Battery Storage Systems

AC Coupled

Where there is an AC coupled battery storage system, there can be a conflict as both the storage system and the eddi are effectively competing to consume the surplus energy. Whilst this is not necessarily an issue, the results can be somewhat unpredictable.

There is the option to add an additional CT sensor to monitor the battery storage; this will give control as to which device has priority. This additional CT sensor should be wired to one of the CT terminals of the eddi or a harvi device if wireless measurement is required. This CT should be clipped around the live or neutral cable of battery inverter.

During the setup process it will be necessary to change the setting for the appropriate CT to AC Battery; refer to CT Config. Also refer to Supply Grid – Battery. for information on setting ‘priority’ of battery systems.


DC Coupled

Battery systems that charge directly from the solar array and cannot change from AC are usually referred to as being DC coupled. This type of battery system uses the solar PV inverter to provide power from the batteries, thus it is not possible to differentiate between solar and battery power when using a CT to measure the AC current from the inverter.

Because of this limitation, there are less options for managing the surplus power with this type of battery system. However it is usually possible to effectively give priority to battery by setting an Export Margin in the eddi. A setting of 50W or 100W is recommend. The Export Margin setting is found in the Advanced Settings/Supply Grid menu.

Third-Party Diverters

Some properties may have a third-party energy diverter already installed and you may want the eddi to take priority (when consuming surplus power) over the other diverter. This is possible by installing an extra CT to monitor the diverter.

The CT should be clipped around the Live cable of the supply feeding the diverter. The arrow on the CT should be pointing away from the diverter. Wire the CT to the nearest myenergi device or use a harvi unit if wireless connection is needed.

Configure the CT Type as Storage Only. See CT Config for details of how to configure CTs.

Voltage Optimisers

If there is a voltage optimiser (VO) installed in the property, the CT sensor and the eddi must both be on the same side of the VO; either the incoming grid supply or the optimised supply.

5. Relay & Sensor Board

eddi has the option to install a Relay & Sensor Board (available separately), this allows for many different wiring configurations and includes the following features:

–   Two independent multifunction relays (16 Amp)

–   eSense input (isolated 230V detection for economy tariff etc.)

–   Two temperature sensor inputs (PT1000)

The two relays can be independently set for several different functions, or they can be set to operate as a pair. The relay functions include:

–   Export Threshold

–   Import Threshold

–   Operate when heating

–   De-stratification pump control

–   Timed operation

–   Fault signal for BMS systems

Refer to Application Examples in this guide and Relay & Sensor Menu for practical examples.


The Relay & Sensor Board is installed by plugging it into the eddi main circuit board using the three plastic spacers included with the Relay & Sensor Board.

The flexible ribbon cable is then pushed into the black connector to the right-side of the display on the top eddi circuit board.


6. Fitting the Cover

Refit the cover and secure with the two M3x12 screws.
Ensure the locating tabs are correctly positioned inside the slots on the chassis before the cover is screwed on.


7. Setup

Switching On

After completing and checking the wiring of the supply, the heater(s) and the sensor(s), switch on the eddi via the circuit breaker or fused spur.

If it’s not already on – switch the Bypass Switch (underneath the eddi) to the ON position.

After the eddi starts-up for the first time, the time and date will need to be set. Refer to the Configuration section on page 19 for further guidance.

By default, the eddi is set to operate as in Application Examples 1: Single Element Water Heater. If the application differs, refer to the specific application example for details of settings that may need to be changed.

If eddi has been installed alongside other eddi units or another myenergi device, refer to Linking Devices for guidance on pairing devices. Also refer to the instruction documentation for the other devices.


Before leaving site, it is wise to perform a few checks to ensure that the sensors and heaters have been correctly installed and are functional.


1. Test the heaters by trying a Manual Boost, and check the power reading on the screen for the heater corresponds to the heater rating.
2. Cancel the boost by pressing the button twice during the boost.
3. When eddi is diverting surplus power to the heater, the grid power figure (above the pylon symbol) should be 0.0kW).

Note: If the surplus power exceeds the rating of the heater then this cannot be achieved and some export power will be observed.

If power is being imported from the grid when the eddi is in Heating mode, it is likely that the Grid CT is incorrectly installed – see Grid CT.

4. If a Generation CT has been installed, the generated power will show at the top left of the main screen.

If the generation reading is missing, the most likely cause is the Generation CT has not been configured – see CT Config. Or, if the Grid CT is instead wired to a harvi ensure the device settings are correct – see Device Settings.