Microgrids can secure additional revenue by providing grid services
In the summer of 2020, Siemens, a German engineering conglomerate, installed a microgrid power system at its corporate headquarters campus in Vienna, Austria. It features solar generation, electric vehicle (EV) charging stations, battery storage and a smart microgrid controller that coordinates connected assets and optimises the power supply to account for peak loads and grid capacity utilisation.
The microgrid plan was conceived when, like many other corporations, Siemens began pushing the use of EVs by its employees and needed a vehicle charging infrastructure. “SRE (Siemens Real Estate), our internal real estate provider, came to us and asked if it was good enough to put some PV on rooftops,” says Robert Tesch, head of digital grid and distribution systems at Siemens Austria and Central and Eastern Europe. “But it wasn’t good enough.” The additional power needs from EV charging meant the company risked exceeding grid access limits exposing them to higher tariffs, he notes. “Every microgrid needs a business case and our business case was peak shaving.”
The microgrid consists of rooftop solar panels stretching over 1600 square meters and with a capacity of 320 kilowatts-peak (kWp), 500 kilowatt-hours (kWh) in battery storage and some 50 charging stations. The microgrid also incorporates a building management system, which provides another source of flexibility via the water boiler in the company’s kitchen. The boiler can be heated either through the district heating system or with electricity, depending on solar production, power consumption and storage needs.
Aside from saving Siemens money on its energy bills, the project illustrates how smart energy management systems can lower emissions by reducing energy waste and avoid the need for additional grid capacity for the uptake of more renewable energy generation. Siemens estimates power from the solar PV panels at the Vienna microgrid will avoid some 100 tonnes of CO2 emissions every year.
The centrepiece of this microgrid—and of all microgrid systems—is the controller. It collects a lengthy list of information from the microgrid ranging from power consumption to the temperature of the water boiler and the charging state of the stationary battery and EV batteries. It also has forecasting capabilities, both for expected solar production and for charging requirements, and puts all available information together to optimise electricity use. There are plans to integrate a Siemens Internet-of-Things (IoT) application into the microgrid, adding extra intelligence to microgrid applications, says Tesch.
Siemens also aims to provide flexibility services to the balancing market of Austria’s electricity transmission system operator via an aggregator, helping to provide stability to the grid and further strengthening the feasibility for the microgrid. While the business case for microgrids depends on many factors, among them grid tariffs and regulatory regimes, Tesch expects the technology used to optimise energy use at the Siemens Vienna headquarters to also have applications beyond the campus and company settings, including in some of the energy community projects that are developing in towns and cities in Austria and throughout Europe in the wake of the European Union’s December 2018 revised renewable energy directive. •
TEXT Heather O’Brian