zappi v1Installation

  1. Mounting
  2. Wiring
  3. Supply Connection
  4. CT Sensor Installation
  5. Advanced Installation Options
  6. eSense Input (economy tariff)
  7. Fitting the Cover
  8. Setup

1. Mounting

1. Remove the white front plate by unscrewing the M3 screw at the bottom and sliding it upwards before lifting it away.
2. Unscrew the 12 M4 screws now exposed and lift off the enclosure cover.
3. Offer the unit 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 enclosure directly into the timber. The two additional mounting points can be also be used if desired.

The supply cable entry can be via the rear grommet or by drilling the enclosure at the bottom right and using a suitable cable gland.


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 40 Amps (B40)

Strip Length

Overview Diagram

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


The zappi device should be connected to a single-phase 230V or 240V nominal AC supply. The supply should be from a dedicated 32A or 40A circuit breaker.


The unit must be earthed in accordance with local regulations, e.g. It may be a requirement to install an Earthing rod if the supply is PME.

Cable Entry

There is a grommet in the rear of the unit for through-wall cable installation. If however, the supply and/or sensors cables are surfaced mounted, there is space at the bottom right-side of the enclosure to drill holes for the cables. It is essential that correctly sized cable glands with a minimum IP65 rating are used.

3. Supply Connection

The zappi device should be connected to a single-phase 230V or 240V nominal AC supply. The supply should be from a dedicated 32A or 40A circuit breaker.

zappi features and integral 30mA Type-A RCD, therefore an RCD protected supply is not required unless local regulations state otherwise.


4. 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 sensor cable

If there is a need to extend the sensor cable, twisted-pair cable like CAT5 or telephone cable must be used. 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 zappi unit needs to

be connected to a sub-board, rather than main consumer unit and two consumer units are in different buildings.

The solution to 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.


5. 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. zappi). The current will not be exceeded even during Boost or Fast charge. Sets the combined current limit for several myenergi devices that are sharing a supply with another large appliance.
Grid Limit Sets the limit that can be drawn from the grid connection (i.e. the maximum import current). The zappi and any other linked myenergi device, will limit the current they draw if there is a danger of exceeding the set Grid Limit. A property may have a grid supply limit of only 65A, several appliances are on and the property is consuming 12kW (52A) by other appliances and the user wants to charge in FAST mode. With a Grid Limit setting of 60A, zappi would temporarily limit the charging current to 8A (about 1.8kW) and the maximum allowed import current would not be exceeded.
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 zappi 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 zappi to use surplus power from any phase and not just the phase which the zappi is installed on. However, you must be sure that the electricity is metered in such a way as to allow this.

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 zappi 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 zappi 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 zappi. 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 installed and you may want the zappi to take priority (when consuming surplus power) over the 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 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 zappi must both be on the same side of the VO; either the incoming grid supply or the optimised supply.

6. eSense Input (economy tariff)

zappi has an input which can be used to sense the availability of economy tariff electricity, this can be used to automatically boost the charge when in ECO or ECO+ charging modes.

The eSENSE input is electrically isolated and effectively draws no current so the cable size is not important. An AC voltage between 100V and 260V across the L and N terminals of the eSENSE input cause the economy tariff symbol to be shown on the main screen. The eSENSE Earth terminal is not required to be connected.

See eSense Input for details of how to configure the eSENSE input.


7. Fitting the Cover

1. Refit the cover and secure with ALL twelve of the M4 screws. It is best to screw these by going around in sequence shown without skipping any holes.
2. Slot the white cover down onto the unit and secure with the M3 screw at bottom.


8. Setup

Switching On

After completing and checking the wiring of the supply, the sensor(s), switch on the zappi via the circuit breaker.

zappi will start-up and the main screen will be presented after a few seconds.

If zappi has been installed alongside another zappi unit 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 have been correctly installed and are functional.

Check that the time and date are correct and displayed at the bottom left of the main screen. If they are not present or are incorrect, set the correct time and date in the Other Settings/Time & Date menu option.
Check that the EV will charge in FAST mode.
Check the Grid Power reading at the top right of the main screen is showing sensible readings and the direction of power flow is as expected.
With the EV plugged in, switch to ECO mode charging and check that the charge power is at minimum (about 1.4kW) OR that it is ‘tracking’ the surplus power (i.e. the Grid Power reading is 0.0kW)
If a Generation Sensor has been installed, check that the generated power is shown at the top left of the main screen.
If the generation reading is missing, the most likely cause is the CT2 input is not enabled – see CT Config. Or, if the Grid Sensor is instead wired to a harvi ensure the device settings are correct – see Device Settings.