The following guide is a condensed guide with all the information needed to install and commission the SH3.0-6.0RS v11/v13 hybrid inverters of Sungrow in the Self-Consumption (ongrid) energy management mode together with a generator.
All the settings needed for proper commissioning of such a system are provided with regards to the interface that is available after connecting to the inverter on-site through local access via the iSolarCloud app.
The designer is responsible for the generator selection and system design. There should be enough generator capacity to supply the loads at all times and charge the battery as well. It is recommended that the rated power of the generator should be greater than the sum of the inverter power and the total load power.
System scheme:
Generator paralleled to the grid port of the hybrid inverter. The generator is able to supply the end user loads and charge the battery. It shall have a DI (Digital Input) port for auto-start function. The use of an ATS (Automatic Transfer Switch) is also needed.
To ensure proper functioning of the system, please update the firmware of SH3.0-6.0RS hybrid inverter with the FW version which supports this function. Please contact Sungrow to receive the compatible FW version information.
Installation:
An ATS needs to be integrated in the system. The grid has to be connected at the primary input of the ATS and the generator at the secondary one. The ATS then switches based on the status of the “main power supply” (grid). Ensure that correct protective devices are used.
The grid port of the hybrid inverter will be connected at the output of the ATS.
A typical switching time of the ATS at around 100ms means that the seamless switching of below 10ms, that is generally possible with the SH3.0-6.0RS, is not guaranteed.
A single line diagram of the system can be seen below:
As shown above, the DTSU666-20 with 2 * 333mV CT is needed – one CT (CT1) installed at the grid connection point and the other (CT2)at the grid output of the hybrid inverter.
The system recognizes that the grid is available whenever there is a flow of power from CT1 to CT2.
A two-wire control cable has to be used to connect the ‘DO’ terminal of the inverter with the DI (autostart) terminal of the generator, as shown below:
A circular 2-core control cable is suggested for the DO of the hybrid inverter so that the IP rating of the gland will not be compromised.
Consult the generator manual for the connections on the generator’s side.
Commissioning:
Commission the system in the same way you would for a grid connected system (Ensure to register the plant on iSolarCloud as a Residential Storage plant and ensure to choose the Self-consumption grid connection type).
The grid code “EN50549-1”, selectable under “Country/Region” in the Device Initialization, can be set during commissioning. If any issues are encountered, where the inverter is disconnected when the generator is turned on, or disconnected as well if/when the generator decreases it’s voltage output due to overload, then the “Others (50hz)” grid code can be set. This specific grid code inside iSolarCloud is the one that has the widest ranges in the protection parameters, therefore it is ideal for the inverter to remain connected to the grid that is formed by a generator.
Reminder: The protection parameter values can also be manually changed to the values of preference.
In any case, Sungrow recommends doing so after having the permission from the grid company.
Once complete, using the local access feature (Account: admin, Password: pw8888), log in to the settings.
Go to Settings -> Energy Management Parameters -> General Parameters -> Grid/Microgrid Adaptation, and enable it. This will set up the DO port of the hybrid inverter for the connection to the generator. The MicroGrid System Mode will be then set in the “DO Configuration” parameter, that can be found under Settings -> Operation Parameters -> Regular Parameters.
Go to Settings -> Energy Management Parameters -> General Parameters -> Energy Management Mode, and ensure that the Self-Consumption mode is chosen.
Go to Settings -> Energy Management Parameters -> MicroGrid system parameters -> Nominal Power of Genset, and set the needed value for the nominal power of the generator.
Go to Settings -> Energy Management Parameters -> MicroGrid system parameters -> Genset Start/Stop Control, and choose “Controlled by SOC”. The generator will start/stop based on the SoC of the battery. You can also test the generator start/stop function from here by using the “Forced Start” and “Forced Stop” control.
Go to Settings -> Energy Management Parameters -> MicroGrid system parameters -> Lower Limit of SOC to Start Genset, and set to the value of preference. Whenever the SoC of the battery reaches this lower limit, the generator will start.
Go to Settings -> Energy Management Parameters -> MicroGrid system parameters -> Upper Limit of SOC to Start Genset, and set to the value of preference. Whenever the SoC of the battery reaches this upper limit, the generator will stop.
Go to Settings -> Energy Management Parameters -> MicroGrid system parameters -> Forbid Genset Night-time Operation, and enable it or disable it based on preference. If the parameter is enabled, then please first set the “Operation Forbidden End Time: Hour” and “Operation Forbidden End Time: Minute” parameters, and then set the “Operation Forbidden Start Time: Hour” and “Operation Forbidden Start Time: Minute” parameters. The meaning of the “Forbid Genset Night-time Operation” parameter is that you can even set a time range when the generator will not be able to start!
Go to Settings -> Operation Parameters -> Off-grid Parameters -> Backup Mode, and ensure that the Backup Mode is enabled.
Go to Settings -> Operation Parameters -> Off-grid Parameters -> Reserved Battery SOC for Off-Grid, and set to the value of preference. This Reserved Battery SoC cannot be used in daily operation as it is reserved for a power outage.
Go to Settings -> Battery Parameters -> Automatic Recharge to Reserved Battery SOC for Off-grid, and enable it. Whenever this parameter is set to Enable, the grid will always also be able to charge the battery back to the Reserved Battery SOC for Off-Grid, whenever the SoC is less than this value.
Additional remarks:
Please note that you can always also set a percentage of the battery capacity that will never be discharged. This “SOC Lower Limit” parameter is accessible under: Settings -> Battery Parameters -> SOC Lower Limit.
By setting here e.g. 5%, the iSolarCloud interface will display 0% whenever the battery is at 5% SoC.
The recommended value is at 10% to avoid battery going undervoltage when there is low PV production and during night / winter.
The “SOC Upper Limit” parameter, accessible under: Settings -> Battery Parameters -> SOC Upper Limit, is recommended to be always set at 100% in order to ensure battery balancing.
The amount of battery charging power from the grid can be limited based on the limit (max. current) of the main house circuit breaker. This can be done by setting the “Max. Permitted Charging Power from AC” parameter, accessible under: Settings -> Energy Management Parameters -> MicroGrid system parameters -> Max. Permitted Charging Power from AC.
A second way to limit the battery charging power from the grid is to set the upper limit for energy purchasing power. This can be done by setting the “Import Power Limit” parameter, accessible under: Settings -> Operation Parameters -> Other Parameters -> Import Power Limit. When the energy meter detects a value close to the limit (the limit should be set a little lower than the main house circuit breaker limit) then the hybrid inverter will decrease the battery charging power.
There is no need to set anything in the “AC Source Type” parameter, which is accessible under: Settings -> Energy Management Parameters -> MicroGrid system parameters -> AC Source Type. There will be no influence at all, as this parameter is not related to the SH3.0-6.0RS.
Running logic:
The expected running logic is as below:
Grid is available: Hybrid inverter works as usually.
Power outage: Hybrid inverter switches to backup mode.
If / when the battery SoC reaches the “Lower Limit of SOC to Start Genset”, the DO port of the hybrid inverter sends instruction to start the generator, for the generator to charge the battery to the “Upper Limit of SOC to Start Genset” and then stop.
Since the generator is connected to the AC port of the hybrid through the ATS, when it starts up the hybrid inverter will again switch to on-grid operation (“Microgrid Operation” will be then displayed in the home page of the plant), and when it stops the hybrid inverter will again switch to backup mode. The inverter is designed to not feed power to the generator, while the generator is working.
Grid is back: The ATS switches to grid input, the hybrid inverter DO connection with the generator is quickly disconnected (the generator will shut down in case it was working at this moment) and the hybrid inverter finally switches back to on-grid mode. If set to do so, the grid will automatically charge the battery to the “Reserved Battery SOC for Off-grid”, in case the battery SoC is lower than this set value.