“Connections to the main grid are located in the most sensible place from the grid-technological viewpoint. Mainly, this means substations. The vicinity of a transmission line in itself doesn’t provide an advantage. Furthermore, a solar power plant is usually connected to a local network, not the main grid,” Fingrid’s Project Manager Mika Penttilä explains.

Larger-scale solar power plants are only just entering the Finnish energy system. Locating them in rights-of-way is not possible, for example due to main grid maintenance work.

“We must be able to reach the transmission lines unhindered with work machines, as well. Rights-of-way also contain the line’s earthing conductors, which must not be damaged. On the other hand, snow and ice falling from the line’s overhead ground wires may damage solar panels underneath. A transmission line is, of course, a conspicuous technical structure, and in some areas, locating solar panels near them could be sensible in terms of the landscape,” Penttilä says.

Locating a wind power plant close to the main grid presents another kind of risk to the grid.

“Whirling currents created by a wind power plant make the conductors swing, if the plant is too close to the transmission line. This can damage the transmission line’s structures. Ice may become detached from the plant’s blades and crash into the conductors. We must also be prepared for the wind power plant falling down. Furthermore, main grid maintenance work utilises a helicopter, which needs space. This is why we have defined the safety distance between the outer edge of the right-of-way and a wind power plant as at least 1.5 times the maximum height of the wind power plant. Wind power operators have taken our instructions into account, and cooperation has been conducted with mutual understanding,” praises Penttilä.

Read more: Pages 28-30 of the planning guidelines deal with wind and solar power (in Finnish)