Storage Cascade MZ: Storage cascade system to establish urban PLUS energy systems on the example of the city of Mürzzuschlag

In the "Storage Cascade MZ" project, battery storage systems are implemented on different grid levels in the city of Mürzzuschlag, whose measurement data enable an integrated grid monitoring and create the basis for a future expansion of the nominal power of photovoltaic (pv) systems.

Short Description

Starting point / motivation

The integration of large-scale PV systems is currently a very relevant problem in the project area of the municipality of Mürzzuschlag, especially since the largest wind farms in Styria (currently approx. 110 MW) are in proximity of the city. This leads to the situation that at peak times the electricity from the planned large-scale PV plants cannot be transported via the 110 kV line located directly in Mürzzuschlag.

Flexibility solutions are therefore needed that allow feed-in at lower voltage levels in order not to inhibit the expansion of renewables. For historical reasons, it was not necessary or not economical to equip medium or low-voltage power grids with measuring devices for grid monitoring.

As a result, operators of medium-voltage and low-voltage grids in Austria are de facto "blind". Therefore, grid monitoring on a real-time basis is required to allow the use of flexibilities on a system level.

Contents and goals

In the "Storage Cascade MZ" project, battery storage systems are to be implemented on different grid levels in the city of Mürzzuschlag, the measurement data of which will enable integrated grid monitoring. This will create the basis for a future flexibility system that will allow for the expansion of the photovoltaic nominal capacity by an additional 60 MW - which equals four times the current grid peak load of 15 MW. The storage cascade will also provide an emergency power supply for at least three days and at least four economically viable energy services in case of a large-scale system failure. The storage-integrated grid monitoring should require 50 % less measurement infrastructure due to the dual use.


In the course of the "Storage Cascade MZ" project, the control systems of the BlueSky storage units as well as the system of the project partner Venios will be further developed to enable a coordinated control of the decentral battery storage units.

The geographical distribution of the battery storage units allows a targeted relief of the grid at the points where they are operated, and a dimensioning based on the local requirements. In addition, the connected system of battery storage units at different grid levels is used to provide emergency power supply to the areas where the storage units are located.

From a project perspective, these additional benefits are associated with only a little additional effort, but the added value for a city would be very high. Furthermore, services and business models will be developed which enable the battery storage system to be operated economically. Part of this development process is the (pro)active involvement of the future users of the system.

Expected results

  • Monitoring based on systems at end-customer level
  • Embedding the battery storage systems in an integrated operation
  • Increased knowledge in grid operation including monitoring of distribution and low-voltage grids
  • New services and business models
  • New control and optimization strategies
  • Application of new flexibilities
  • New application area for storage technologies
  • Emergency power supply via storage cascade more easily possible

Project Partners

Project management

4ward Energy Research GmbH

Project or cooperation partners

  • Stadtwerke Mürzzuschlag GmbH
  • BlueSky Energy GmbH
  • Wasserverband Mürzverband
  • Venios GmbH

Contact Address

DI(FH) DI Martin Schloffer
Reininghausstraße 13A
A-8020 Graz
Tel.: +43 (664) 885 003 38