How are multiple ESS batteries connected in parallel?

*NOTE: The information below is directed towards installers. Only trained electricians are allowed to install Ferroamp’s products.  

Answer:

Expand the system by paralleling more ESS batteries

The Ferroamp system can also be expanded by paralleling multiple ESS batteries. It is possible to parallel up to a maximum of six batteries, with the requirement that they have the same number of modules in each battery being connected. Note that this applies only to ESS batteries with main controller V2. To check which version your main controller is, verify the "article number" on the Pylontech label.

Article number 11FC0500MZA-00013 indicates V2 and is compatible with parallel connection.

Article number C0500MA01V00102 and 11FC0500MZA-00005 are V1 which are not compatible with parallel connection.

By doing this, the system's storage capacity can be increased from 14.2 kWh (one stack with four modules) to 85.2 kWh (six batteries with four modules each). The image below illustrates an example of this. However, the power output will not be affected by the number of batteries. Instead, the power output is still governed by the number of modules in the batteries and the number of ESOs. The maximum possible power output remains at 8 kW.

How do I parallel connect mulitple ESS batteries?

To parallel connect multiple ESS batteries, the DC cable from each stack needs to be connected to a DC distribution, as shown in the image below. This can be achieved using our Power Distribution Box, but you can also explore other options. Our recommendation is to isolate each battery separately, which is achieved when they are connected to one of our Power Distribution Box 5/8 SSO. The cable coming out from the DC distribution should then be connected to the Bat + Bat - positions on the ESS Power Case, where the battery is connected in the Power Case.

Between each main controller, communication cables, specifically CAN cables, need to be connected, as illustrated in the image below.

Startup of paralleled ESS batteries

When starting up the batteries, the same principle applies here as when starting up a single stack. First, the EnergyHub should be started, and the DC grid should be charged. Then, the batteries should be started. When starting up paralleled ESS batteries, there is a specific sequence in which the batteries should be started. The image below is taken from the comprehensive Pylontech manual and it shows the order in which the batteries should be started.

If we consider the image above where six batteries are connected together, the batteries should be started from right to left, starting from the slave furthest away to the master at the end. To start the battery, switch on the breakers and then hold down the red button until it beeps.

1. Start the EnergyHub by turning on the AC breaker

2. Turn on the breakers in the DC grid

3. Start the batteries (Slave 5 -> Slave 4 -> Slave 3 -> Slave 2 -> Slave 1 -> Master)

Turn off batteries:

1. Turn off the EnergyHub by turning off the AC breaker

2. Turn off the breakers in the Power Distribution Box to ESS

3. Turn off the braker on the main controller

How do I proceed if I already have an ESS battery with the older version of the main controller and want to parallel connect multiple batteries?

In order to parallel connect multiple ESS batteries together, they must all have the V2 version of the main controller. If you have an existing battery with the older model of the main controller, it needs to be replaced with the new version; however, the modules remain the same. Once the main controller is replaced, it is installed in the same manner as described in the information above.

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