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Reliable supplies through emergency current systems

Reliable supplies through emergency current systems

Lithium ion storage units in photovoltaic systems are currently used almost exclusively for the optimisation of self-consumption. Unlike older lead acid battery systems, using them to provide a reliable supply of electricity in the event of power failures is less common, however it can make perfect sense in individual cases nowadays. In line with the difference helpfully defined by SMA between emergency and backup power, we will be looking at the options available for backup power systems from various manufacturers.

Essentially, to set up backup power systems, switchover devices are needed which, in the event of a power failure, disconnect the public grid from the building connection. The background to this requirement is that, after the backup power network from the battery switchover device is established, no unwanted should be returned to the grid, thereby endangering engineers or grid maintenance, for example. This separation takes place fully automatically through a protection device, as does the re-connection once the grid is available again.

So compared with a storage system for self-consumption optimisation alone, only one additional component is required. The table below lists the possibilities.

It should be noted here that in the 3-phase system illustrated above, the supply is made up of alternating current only. Essentially, all of the switchover devices we offer come with phase couplings, allowing all 1-phase consumers to be supplied over the 3 phases.

These backup power systems are not uninterruptible power supplies (UPS), which means that computers and other electronic device may switch off for a short period. The switchover time for all systems is between 5 and 10 seconds.

With an average of around 12 minutes of supply interruption per year in Germany, procurement is not an economic, but rather an application-specific consideration. The fact remains, however, that synergy effects can be harnessed through the simultaneous use of batteries and PV, since the grid-neutral supply can be extended significantly through the direct use of the PV system.

29.08.2018 12:18
by Maik Wünsche

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