TÜV SÜD is accredited for testing services in accordance with the VDE 4105 standard. On the basis of this accreditation, the embedded systems experts can now test the standard conformity of photovoltaic systems, inverters and other distributed power production units.

TÜV SÜD is one of the first test organisations to become accredited by Deutsche Akkreditierungsstelle (DAkkS) for this scope in Germany. "Local power distribution networks are increasingly receiving electricity feed-in from photovoltaic systems via inverters", says Christian Dirmeier, Product Manager at the Embedded Systems unit at Munich-based TÜV SÜD AG. "Standard conformity of PV systems ensures that weather-dependent fluctuating feed-in of energy does not put network stability at risk." Problem-free grid integration is one of the areas on which efforts towards the further expansion of photovoltaics are centred.

In 2012, the VDE-AR-N 4105 standard introduced stricter requirements for power production units connected to the low-voltage network and established the basis for improved integration of these systems. The standard is not only relevant for PV systems but also applies to all types of distributed power generators, such as small CHP systems. "The new standard introduces some new requirements, for example regarding the grid and system protection function", explains Christian Dirmeier. This function reliably separates the power production unit from the grid to prevent any undesired or faulty feed-in of electricity. A new aspect according to the TÜV SÜD expert is that the power generation units may now not be separated from the grid before a network frequency of 51.5 Hz is reached; in the past they were separated at a network frequency of 50.2 Hz. This change is designed to improve network and system stability and supply quality.

As an accredited body, TÜV SÜD assists manufacturers and owners/operators with the testing and certification of power production units and their integration into the low-voltage network in accordance with VDE V 0124-100. While the VDE 4105 standard establishes the requirements for power production units connected to low-voltage networks, VDE 0124-100 describes how the devices must be tested. Testing is performed in TÜV SÜD's own accredited testing laboratory for smart energy technology.