By Nicholas Earl SSE has sold a 25 per cent stake in its electricity transmission network in Scotland to the Ontario Teachers’ Pension Plan Board for £1.5bn. The network helps transport renewable resources in the north of Scotland to where demand is highest. It is expected to go through in early 2023, the London-listed firm revealed in a statement to investors. The announcement concludes a year-long search to find a buyer for a stake, with the energy firm is eager to raise funds for its investments in wind farms. The sale is part of a strategic plan unveiled by SSE in response to activist pres…