SMA Solar Technology AG is the first solar inverter manufacturer whose equipment has been certified according to the technical directive for “Power Generation Equipment Connected to the Medium-Voltage Power Grid” issued by the German Federal Association for Energy and Water (Bundesverband der Energie- und Wasserwirtschaft in German, BDEW). Germanischer Lloyd carried out the certification process for SMA’s central inverters Sunny Central 400HE-11, Sunny Central 500HE-11, and Sunny Central 630HE-11. Among other things, the directive requires for the first time ever equipment to have the ability to feed reactive power to the grid. SMA is currently the only inverter manufacturer to receive certification pursuant to the BDEW’s Medium Voltage Directive. As the leading inverter manufacturer, SMA was faster than its competitors in offering certified equipment that meets the requirements of the Medium Voltage Directive. With the certified inverters, PV systems can now contribute to voltage stability and ride-through capability. As a result, the conditions have been created to allow more photovoltaic systems to be integrated into the distribution network. As established in the BDEW’s directive, the unit certification is, in turn, the prerequisite for receiving system certification for PV systems with an output of 1 MWac or more.
After incorporating the first wind energy plants into the grid control system long ago, corresponding regulations and guidelines have now also been in place for larger PV systems since the beginning of 2009. The amended German Renewable Energy Act sets forth that in general, systems with an output which exceed 100 kW must participate in the feed-in management system: they must be able to restrict real power fed into the grid by a defined percentage of their nominal power at the network operator’s request. The BDEW’s Medium Voltage Directive applies to all energy generation systems which feed power into the medium-voltage grid. It was updated during the summer of 2008, and, in addition to the "grid stability management", it also creates far-reaching requirements for the plants. For example, similar to high-voltage and ultra-high-voltage grids, generation systems which feed power into the medium-voltage grid must also participate in grid controls. During normal operation, they must contribute to voltage stability in the medium-voltage grid by feeding in a desired amount of reactive power, and they are no longer allowed to immediately disconnect from the grid in case of failure. The purpose of these extremely complex technical requirements is to maintain the stability of the grids even in case of failures. Similarly strict regulations are increasingly applied in other countries as well. “Companies like SMA, which are globally active and have already received certification, offer their customers a high level of security in knowing that their products are future-proof,” says Roland Grebe, SMA’s Chief Technology Officer.
Grebe views the directive as an important prerequisite for expanding the use of photovoltaic technology: “To achieve the goal established by the European Photovoltaic Industry Association (EPIA) of generating twelve percent of Europe’s electricity from solar sources by 2020, a comprehensive grid management system is an absolute requirement. That’s why SMA has been active in this area from an early stage.” Photovoltaic technology offers the best conditions for extensive grid integration because PV electricity is primarily generated during peak load periods and generally fed into the grid in a decentralized way. According to Grebe, appropriate directives must be created together with the electric companies in order to achieve the PV output in Germany set forth in the EPIA’s objective. “Increasingly incorporating photovoltaics into grid management is only logical. On the one hand, inverters are best for these tasks. On the other, participation is a prerequisite for expanding the use of photovoltaics.” Uniform requirements on equipment and interfaces are crucial in this regard. Moreover, they make it possible to offer operators, particularly those running larger PV plants, an affordable network connection point. This results in reduced connection costs as well as planning security for investments.
SMA Solar Technology AG
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