Using a battery with your myenergi system

A very common question is "how do I set up my myenergi devices so that they work with a battery?"

Although we can't control a third party battery directly, the myenergi devices have been designed so that they "play nicely" with a battery if one is fitted. As the battery and the myenergi devices are both trying to control the power flowing to / from the grid they can fight each other, leading to unexpected results.

The exact answer depends on what sort of battery has been fitted:

• a standalone battery that is completely separate from a PV panel or other renewable generation
• a "hybrid" battery where the battery and the PV panels both feed into a single "inverter"

In both cases, most customers want to avoid emptying their battery into their EV or hot water when the myenergi devices should be working from any spare PV (or other) generation that this available.

Please note - if zappi or eddi are "boosting", or zappi is FAST mode then power will always be taken from your battery, unless the battery is turned off.

The simplest setting

The simplest way to stop your eddi or zappi draining the battery is to set an "Export Margin".   

This means that the myenergi devices will not start to divert power until they measure power being exported that exceeds this level.  The battery then has a chance to control first, taking the surplus generation.

There is a small drawback in this approach as, once the battery is full, you will see a small amount of power being exported to the grid.

To set an export margin, the menu is

• Zappi: Settings - Advanced - Supply Grid - Network - Export Margin
• Eddi: Setting - Advanced - Supply Grid - Export Margin

A value of 50W or 100W should be suitable.

If you have more than one myenergi device this setting needs to be set on the "master" device
Note:  If you have the Export Margin set then, on zappi, the "Minimum Green Level" or "MGL" needs to be set at 100%.

Standalone Battery

With a standalone battery, you have the option to install an extra current transformer (CT) on the wire from the battery to your consumer unit.  With this CT, your myenergi devices can measure the power flowing to / from the battery and then ensure that the zappi / eddi does not take power from the battery when they should be using any surplus renewable generation.

The CT will normally need to be installed by an electrician and should be connected back to your zappi / eddi - either connected directly or via a harvi wireless transmitter.  If needed, extra CT's can be bought through the myenergi website at myenergi.com.

Once the battery CT has been connected, the following needs to be set in the zappi/eddi

• Set the CT type to "battery" 
• Tell the zappi / eddi to "avoid draining" the battery.  The menu is
  • Zappi: Settings - Advanced - Supply Grid - Network - Battery
  • Eddi:  Settings - Advanced - Supply Grid - Battery

If you have more than one myenergi device the battery setting needs to be set on the "master" device

When you have a battery CT fitted, you will also be able to see the live battery power flows in the myenergi app.

Hybrid Battery and PV Inverter

With a hybrid battery system it's not possible for your myenergi devices to work out whether the power is coming from the PV panels or the hybrid battery.  In this case the only option is to set the "Export Margin"  (see Hybrid PV and Battery - How to stop your myenergi devices draining the battery in ECO+)

If you decide to fit a CT on the output from the hybrid inverter then you can still monitor the live power flows from the inverter in the myenergi app.  The CT type should be set to "Generation + Battery"

Depending on where the battery and myenergi devices are connected in your electrical system it may be possible to wire them so that they work better together.  This article provides examples from two myenergi customers: Hybrid Battery Installation - Alternative Connection Arrangements