Operation manual
Page 20 of 37
sonnenBatterie Evo storage system automatically switches from grid to backup
operation and vice versa. In the event of a grid failure, the storage system automatically
detects the grid outage and will disconnect itself from the public electrical mains and will
create a micro-grid using the power from the batteries. Appliances connected to
essential loads circuit in the house will be supplied with electrical power. Appliances
connected to normal loads circuit in the house will not be supplied with electrical power.
During the backup operation, the micro-grid produces grid-quality voltage and
frequency so that any grid-connected PV inverter in the micro-grid will continue to
operate. Therefore, during backup operation, the essential loads circuit will be powered
by the energy stored in the battery modules and the PV energy generated from the PV
array. The generated PV power will also charge the battery modules, depending on
generation and consumption levels.
The PV array will first power the loads on the essential load circuit, with any excess
energy charging the batteries in the storage system. If there is insufficient PV to cover
the loads, the storage system will discharge its batteries to meet the demand. The
storage system can also turn the PV inverter off if the battery modules become fully
charged.
To prevent battery overcharging while in backup mode, the storage system will perform
a frequency shift by raising the frequency to a value outside the PV inverter’s operating
range. This shift in frequency will disconnect the PV inverter from the micro-grid while
the storage system will maintain the power supply to the loads. The storage system will
reduce the frequency to 50 Hz once the state of charge falls below a certain threshold
to allow for a charge event. The PV inverter will then automatically detect the frequency
adjustment and re-connect to the micro-grid.
Microgrid Re-Enabling
If the battery SOC drops to a minimum threshold during backup operation:
1.
The micro-grid will be deactivated, and the system will go to ‘standby mode’. The
essential loads and the external PV inverter on the micro-grid will disconnect
consequently.
2.
The system will remain in ‘standby mode’ until the system time reaches the
“Reenabling time one”, as previously set in the commissioning process. Then, it will