Removing Barriers for Participation of Small PV Systems in Balancing Energy Markets by Utilizing the Established Smart Meter Eco-System

With the number of PV systems installed in Germany rising again since 2018, the provision of system services is increasingly coming into focus. On sunny off-peak days, the use of PV systems to provide balancing power will be indispensable in the future power grid [1]. This paper is based on a joint project, which is funded by the Ministry of Science, Research and the Arts of Baden- Wiirttemberg, with the goal to develop a solution that will enable a large proportion of all photovoltaic (PV) systems to participate in the balancing power market [2]. In the context of the European harmonization of energy markets, the balancing energy market is therefore also undergoing change. In principle, PV plants have a very high potential for providing negative balancing power. Small PV systems with an active power limitation (peak power capping) of 70% can additionally provide considerable amounts of positive control power. Technically, cost-effective control of small-scale PV systems via the German smart meter infrastructure is a very attractive option based on the findings presented in this paper. Regulatory hurdles, such as prequalification or market conditions in the balancing energy market can also be overcome in the foreseeable future, in the view of the proj ect partners. However, stronger support at the political level is necessary for their timely elimination. An important step for a cost-efficient technical solution for the control of small PV plants results from the implementation obligation from the German federal law for the digitalization of the energy transition [3]. This conversion to smart metering represents an essential metrological basis for participation in the balancing energy market.As an additional benefit, the introduced intelligent metering system (iMSys) can also be used to control PV systems. The communication channel available for iMSys can essentially be shared here for controlling local plants without much additional effort. This paper proposes a concept that connects all systems involved to realize such an optimised plant controllability. For this purpose, a local control device (so-called CLS-gateway) connects the PV inverter with the remote control system of the balancing service provider (BSP). For communication, the secured channel provided by the iMSys is used, which is encrypted by the highly secured Smart Meter PKI. For the communication between the field device and the BSP control system, the MQTT protocol based on the publish-subscribe scheme is used [4]. The data models used are based on IEC 61850-7-4/420, but in contrast to the standard, they are mapped in JSON and not with MMS.