Service Tip: Setting up Sunny Boy Storage to control export of SMA PV inverters

AC-coupled battery storage allows any new or existing PV system to flexibly add battery storage. The new Sunny Boy Storage is the simplest solution for adding battery storage to PV systems using new high voltage batteries such as the LG Chem RESU10U. However when adding battery storage to a PV system, grid operators may place additional requirements on the system such as limiting the export of energy from both the battery and PV inverters to the grid. With its smart capabilities, the Sunny Boy Storage is able to limit export of energy to the grid not only for itself, but also for up to three SMA PV inverters.

Configuration of the Sunny Boy Storage

One advantage of the Sunny Boy Storage and its AC-coupling is it provides flexibility for deciding where to install the battery and inverter. The diagram below shows the configuration which will allow the Sunny Boy Storage to control the export of either a Sunny Boy or Sunny Tripower. The Sunny Boy Storage is able to control the output for a maximum of 3 additional SMA inverters. For systems which do not use a Sunny Home Manager, it is recommended to connect the SMA Energy Meter directly to the Sunny Boy Storage.

Connection of a Sunny Boy Storage with either a Sunny Boy or Sunny Tripower

At the moment, only one Sunny Boy Storage can be installed per solar system. In a three phase system, the Sunny Boy Storage is connected to one of the phases. It should be remembered that there is no financial benefit for residential energy consumers for using three phase compared to single phase storage. This is because residential systems are both billed and controlled according to their net consumption or generation. By installing single phase storage with three phase generation, the customer is able to get the maximum benefit from their storage but with lower capital costs since single phase inverters are cheaper than three phase inverters.

Setting up Zero Export with the Sunny Boy Storage

Export limitation for a PV system can be achieved with the Sunny Boy Storage and SMA inverters with Webconnect functionality.

For an export limitation solution you will need:

• Sunny Boy Storage
• SMA Energy Meter
• Sunny Boy or Sunny Tripower with Webconnect (maximum of 3 PV inverters)
• Grid Guard Code

The inverters must be installed with their latest respective firmware.

Export limitation for the system using the Sunny Boy Storage can be setup during the initial configuration of this inverter. Follow the normal setup procedure via the web user interface. In step 4 of the inverter configuration, the energy meter will show up connected to the network. You will need to select the SMA Energy Meter from which the generation & consumption data will be obtained.

In step 5 set “Feed-in management at the grid-connection point” to “ON”.

Nominal PV system power needs to be set to the value of the PV system size, tasking into account all the capacity of all PV inverters being controlled.Under “Operating mode of act. power limit  at grid connection point” you can set the parameters to be displayed in terms of percentage or in watts. After this, change “Set active power limit at grid connection point” to value “0”.

The solar inverters need to be set s it receives the ouput values from the Sunny Boy Storage to control their active power. Inverters may already be configured to accept control of active power via PV system control. In this case there would be no additional steps. However if this is not set for the inverters the following steps will need to be undertaken.

Configuring Solar Inverters for Active Power Limitation from Sunny Boy Storage

To configure the inverter you will need to first connect to it. For inverters with built in Wifi connect to the respective inverter’s Web User Interface (WebUI, see here for instruction how to do this if necessary). For SMA inverters with only Webconnect functionality, connect using Sunny Explorer (see here for instruction how to do this if necessary). Once connected to the inverter log on as an Installer, input your Grid Guard Code. For the WebUI enabled inverters navigate to Device parameters, while in Sunny Explorer navigate to Settings.

For the WebUI navigate to System and device control > Inverter > Configuration of feed-in management. For Sunny Explorer navigate to Equipment & device control system (solar inverters) > Configuration of active power P limitation > Configuration of feed-in management.

Make the following changes:

• Grid disconnection of 0% feeding = No
• Operating mode Active power = Act.power lim. Via PV system.

After completing the commissioning of the Sunny Boy Storage, the source of measurement for export control will need to be set so the Sunny Boy Storage will accurately control its own and other inverter’s output power.  To do this navigate to Device Parameters > System and Device Control > Inverter > Configuration of system control via communication and set Source of ref. meas. for reactive/active power reduction to SMA Energy Meter.

It may also be necessary  to configure fallback settings on the solar inverters, depending on the requirements of the system. These will control the output of the system in the event communications between the PV inverter and Sunny Boy Storage is lost. To configure fallback settings on the solar inverter, via the WebUI navigate to System and device control > Configuration of system control via communication > Act. Power lim. Via PV system ctrl. Via Sunny Explorer navigate to Equipment & device control system (solar inverters) > Act. Power lim. Via PV system ctrl.

Make the following changes:

• Operating mode for absent system control = Use fallback settings or Values maintained
• Timeout = time in seconds a loss of communication is permitted before the inverter should respond
• Fallback active power P = Active power the inverter should default to in the absence of control from the Sunny Boy Storage

It may also be necessary to change the speed with which the solar inverter responds when modifying its Active power upon receipt of a command from the Sunny Boy Storage. To modify the speed of response, via the WebUI navigate to System and device control > Inverter. For Sunny Explorer navigate to Equipment & device control system (solar inverters) > Inverters.

Make the following changes:

• Active power gradient = a value of 200% should ensure the inverter will respond within 3 to 10 seconds

Conclusion

The Sunny Boy Storage can be used to achieve export limitation when used with SMA Sunny Boy or Sunny Tripower inverters. The PV system can be visualized through the web user interface of the Sunny Boy Storage. The system can also be visualized through SMA’s online monitoring platform Sunny Portal. And thanks to the Sunny Boy Storage’s AC-coupled philosophy, it can be added to any new or existing single or three-phase PV system at any time.

Author: Sujan Shrestha, Co-Author: Scott Partlin