Battery Backup Function: Solar Power – Even in the Event of Grid Failure.

Power outage? In South Africa? It hardly ever occurs anymore, if the statistics can be trusted. The national power grid has been lacking the necessary maintenance. This is now causing outages at an ever-accelerating rate. Public attention is shifting back to the significance of emergency power supply. Battery backup systems fulfill this function. Anyone who has dealt with long periods of outages can tell you that it is a major hassle.

You lose power to your pumps, refrigerator, telephone, lights and so on. A PV system on its own disconnects from the utility grid immediately in the event of a power outage. This by design and law. A PV system or a Smart Home system should be able to continue using your solar power, even during a power outage.

A battery backup supplies selected loads with electricity during power outages. A PV system with a storage system continues supplying electricity. Many PV system operators have already started implementing intermediate storage systems for their power to increase their self-consumption. For this reason, it makes sense to add a battery backup function.

The Sunny Island makes it convenient to retrofit the SMA Flexible Storage System with a battery backup function. Designed to increase self-consumption, the battery can now also continue to supply power to loads in the event of a grid failure.

Why do I need a battery backup function in the first place?

PV systems disconnect from the utility grid during a power outage to protect the people working on the utility grid. An extra operation mode with expanded control is required for the PV inverter, battery storage system and the rest of the system to continue to operate without the grid in stand-alone mode. This is what the battery backup function provides.

How does the SMA battery backup function work?

Battery backup systems consist of the Sunny Island battery inverter and an automatic transfer switch. Used in new or even existing systems. Certified by the professional trade association, the concept consists of three functional units:

Grid disconnection:

If the Sunny Island detects a grid failure, the system opens two redundant tie switches. The system is then disconnected from the utility grid.

Grounding unit:

This system provides reliable grounding of the neutral conductor during grid failure. The grounding unit features two contactors.

Phase coupling (optional):

It enables combined switching of the line conductors. As a result, the other two line conductors are also supplied with voltage. In the event of grid failure, a three-phase battery backup grid becomes a single-phase distribution grid.

Once the household and PV system are cut off from the utility grid during a power outage, the Sunny Island battery inverter creates a grid using the power from the batteries. The switching time between grid failure and continuation of power supply to the loads takes only five seconds. A small battery-powered UPS can power sensitive loads (e.g., desktop computers). Once the switch-on delay time for the PV inverters has elapsed, they synchronize themselves with the battery inverter grid. The PV inverters can supply power to loads or to the batteries (in case of excess solar power).