Wien Energie put Austria’s largest photovoltaic system into operation on Wednesday. It was built on the area of a former gravel dump in the Danube city on 12.5 hectares. From now on, the 11.45 megawatt system will produce over 12 gigawatt hours of electricity for 4,900 households in Vienna, explained City Councilor for Finance Peter Hanke, City Councilor for Climate Change Jürgen Czernohorszky and Neos Energy Spokesman Stefan Gara on Wednesday. At the same time, agricultural use is possible, as the operators announced. The giant solar power plant with its 25,626 modules saves 4,200 tons of CO every year2 and thus make a decisive contribution to more climate protection in the city, it said on Wednesday.
Roof systems are not enough
In Vienna, photovoltaics plays the greatest role in the energy transition: every roof, every unused area is needed to achieve the climate targets. The climate targets cannot be achieved with roof systems alone. This also requires nature-friendly open space systems such as those in Schafflerhofstrasse in the Danube city. Last year, Vienna’s largest solar power plant to date went into operation in Unterlaa. The new system is now six times as big, explained Michael Strebl, Managing Director of Wien Energie.
The area under the solar power plant serves as pasture for more than 150 Jura sheep from April to October. As natural lawnmowers, these animals ensure that the grass does not get too high – and thanks to the photovoltaic modules, they are also protected from the onset of the weather.
Part of the system is also implemented as a so-called agricultural photovoltaic system. The 400 or so modules are bifacial – that is, they produce electricity on both sides – and are vertical. A tractor can drive between the module rows without any problems and the area can be used for agriculture, for example for growing vegetables. The area between the agricultural photovoltaic modules is used up to 60 percent more efficiently. This innovative form of photovoltaics has already been successfully implemented by Wien Energie in test operation and is now being used on a larger scale in Schafflerhofstrasse. In order to analyze the effects of the double use, the company relies on accompanying research together with Boku, which will also cultivate the area.
Storage operation from summer
With systems of this size, the connection to the power grid is also a challenge, according to Strebl, as this could be overloaded during production peaks. Wien Energie has an innovative solution for the 11.45 megawatt system: the Schafflerhofstrasse photovoltaic system is part of a “hybrid power plant”. It hangs on the same power line as the Wien Energie wind farm Andlersdorf. This delivers up to 9 megawatts of power into the power grid. Wind and sun peaks are seldom at the same time, so both systems can run in full operation at the same time without overloading the power grid, as Strebl went on to explain.
However, if renewable electricity should be produced one more time, a buffer electricity storage system would be used. “It catches production peaks and only feeds the solar power produced into the power grid at a later point in time,” it said. The storage facility is scheduled to go into operation by the summer.