Switzerland's largest solar power plant is connected to the grid

The leading Swiss solar company TRITEC has realised the largest solar power plant in Switzerland for Migros with an output of 5.21 MWp. After a construction period of less than five months, it was put into operation in mid-August.

The solar module front rows on the roof edges are already visible from the A1 motorway. What you can't see: There are more than 20,000 additional solar modules on the huge roof surfaces of Migros-Verteilbetrieb Neuendorf AG, which were installed in stages by qualified solar installers from TRITEC . Over the next few decades, they will convert the sun's rays into sustainable energy at the southern foot of the Jura.

The solar power plant with a total output of 5.21 MWp (megawatt peak) consists of four photovoltaic systems distributed over six buildings. A total of nine flat roofs are covered with 20'039 monocrystalline 260 Watt solar modules. The total module area is over 32'000 m². Over 60 string inverters and 12 central inverters from SolarMax, the Swiss manufacturer Sputnik Engineering AG, are used as inverters.

Specially developed substructure

The choice of the substructure required special know-how and specific calculations to meet the static conditions of the flat roofs. For a weight-neutral roof load, the green roof (substrate) therefore had to be extracted and replaced by gravel. In addition, the newly developed, particularly low-ballast and aerodynamic TRI-FLAT mounting system was used for the elevation of the modules. The mounting system with an optimised inclination of 10 degrees is slightly oriented towards the southeast.

Transformer compact stations installed directly on roofs for the first time.

"With the two partial systems of 1.7 MWp and 2.0 MWp, we feed the solar power directly into the medium-voltage grid on the roof for the first time," says Roland Hofmann, Managing Director of TRITEC AG, Switzerland, "in this way we avoid possible losses and bring the electrical energy quickly and optimally from 320 volts low voltage to 16,000 volts medium voltage."

The compact stations, weighing several tonnes, were hoisted in two steps by a load crane onto the roofs of Migros-Verteilbetrieb Neuendorf AG, which are up to 20 metres high - first the housing and then the transformer. The transformer compact stations with a rated power of 1.6 MVA and 2.0 MVA come to rest on specially poured concrete foundations.

Energy for over 1,300 households

The energy generated will be fed into Elektra Neuendorf's electricity grid. The photovoltaic power plant will produce 4'836'000 kWh of clean solar energy annually. This corresponds to the average consumption of about 1,300 households. Thanks to the pollution-free energy production of this solar power plant, 2,853 tonnes of CO2 can be avoided annually.

For the turnkey project, TRITEC as general contractor took over the project engineering from the design calculation to the construction planning and commissioning.