The Elektrizitätswerk Zürich (EWZ) sees the construction of solar plants in the high alpine regions of Switzerland as a secure mainstay. The utility is planning another solar plant on the dam wall of a hydroelectric power plant high up in the mountains. The company plans to install more than 1,000 solar modules with an output of 350 kilowatts on the 690-metre-long dam wall of Lago di Lei in Graubünden. The system will cover the dam wall over a length of 550 metres and, once completed, will supply around 380 megawatt hours of electricity each year.
Making optimal use of existing infrastructure
This is already the second installation of this kind to be completed by the EWZ. The first is at the dam of Lake Albigna, also in the canton of Graubünden. This plant has been in operation for a year and has fully met the expectations of the EWZ, so that the forecasts for the new plant are also good. As there, the electricity at Lago di Lei, directly on the border with Italy, will also be fed in via the grid connection of the associated hydroelectric plant of the Hinterrhein power station (KHR). "This makes optimal use of the existing infrastructure to make a further contribution to electricity production from solar energy," emphasises Guido Conrad, director of the CHR.
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But the already existing grid connection is not the only advantage of the plants on dam walls high in the Alps. Because at about 1,900 metres above sea level, solar irradiation is 25 per cent higher than in the Swiss lowlands.
Plenty of solar power in winter
In addition, the modules are mounted vertically so that no snow remains on them in winter. This increases the yield, especially in the season when the most electricity is needed. This has already been shown in the operation of the system at the dam of Lake Albigna. There, about 50 per cent of the total electricity was generated in the winter half-year. The months of March and April in particular were very productive. In its first year of operation, the plant produced 527 megawatt hours of solar electricity. The forecast was 509 megawatt hours. "The measured values prove the efficiency of high-alpine plants and that they contribute positively to the security of supply in winter," explains Philippe Heinzer, Head of the Energy Division at EWZ.
Electricity for EWZ customers
The municipality of Ferrera, to which the dam belongs, has already granted the building permit for the plant on Lago di Lei. In the early summer of 2022, the installers from KHR will start attaching the modules to the dam wall. The planning and financing of the project has been taken over by EWZ, which is also the owner and operator of the solar plant. It will sell the electricity to its customers under the EWZ Pronatur and EWZ Natur tariffs. Moreover, it will not be the last project of this kind. "EWZ is keen to evaluate and develop further locations for such plants," says Philippe Heinzer. (su/mfo)
