The process of preparing the technical information – which will provide the foundation for detailed bids – has been extended to “take account of the level of interest received” and the range of technologies potentially involved.
But SHEPD said the work is now “well advanced” and on course to be completed by the end of April this year.
Last year the network company received more than 300 responses to its consultation with the public, stakeholders and the supply chain to find the most cost-effective solution for keeping the power on after the existing Lerwick Power Station comes to the end of its operational life.
The competitive tender allows interested parties to bid in with solutions, including new generation technologies, measures to manage or reduce demand, and other smart grid solutions.
A pre-qualification process was completed during the summer and autumn of 2015 through which potential suppliers were invited to come forward.
Newly appointed project manager at SHEPD, Dan Pearson, said: “The process is unavoidably complex in order to make it as open as possible to all technologies, so that the most economic overall solution can be identified.
“We are making good progress and will be working hard with Ofgem over the coming months to ensure that the tender documents establish a strong foundation for the future of Shetland’s electricity supply.
“We have been very pleased with the level of engagement we have had to date from the supply chain and from the community. I would like to thank all concerned for their interest and their patience while our team prepares the crucial next stage.”