Overall, the average duration of power outages in Germany has been steadily decreasing. In 2020, the figure was 10.73 minutes—exactly 1.47 minutes lower than in 2019. The main causes of power outages are damage or faults in the grid, often caused by severe weather. The transition of the power supply toward an increasing share of renewable generation has so far not had—and, according to expert estimates, will not have in the future—a negative impact on security of supply.
Nevertheless, the desire for security of supply and independence among the population is high. The following section takes a closer look at the topic.
In principle, most photovoltaic systems—and in particular their battery inverter or hybrid inverter—require power from the public utility grid in order to operate. In the event of a power outage, an inverter will therefore usually no longer be in operation.
A suitable backup-power-capable inverter in combination with a battery storage system can supply selected loads during a power outage via a separate output of the inverter—this could, for example, be a standard emergency power socket. To do this, the devices that are to remain supplied during a blackout must be connected manually to this output. Automatic switching to backup power operation is not common. Thanks to the energy from the battery storage system, the inverter can continue to operate and discharge the battery. Some inverters can only make the stored energy available, while others can also recharge the battery—provided the PV system is currently generating electricity. Depending on the inverter, the backup power supply usually works on one phase, and sometimes also on three phases, at the separate output. No additional components are required here, which keeps costs low.
With a suitable full-backup-capable inverter and battery storage, the photovoltaic system can also continue operating. The prerequisite for this, however, is the automatic disconnection of your home from the public grid in the event of a power outage, usually with the help of a so-called grid changeover box, which is now already available for many of the common manufacturers on the market. This temporarily creates a separate internal power grid within your home, which—depending on the installed system—is maintained by the battery charge and newly generated electricity from the photovoltaic system. This “island solution” remains in place until grid power is available again or the energy in the battery storage is depleted—provided no new electricity from the photovoltaic system is used to recharge it.
Status: December 2021. All information provided without guarantee.