THE start of an inquiry into an ill-fated green energy scheme that triggered the collapse of powersharing in Northern Ireland has been delayed.

The Renewable Heat Incentive (RHI) probe being chaired by retired judge Sir Patrick Coghlin, which had been due to open next month, will now commence hearings on November 7.

Democratic Unionist leader and former first minister Arlene Foster, whose role in the scheme was at the heart of the political row that triggered the collapse of powersharing at Stormont, is not expected to give evidence until the new year.

Sinn Fein has repeatedly indicated its unwillingness to return to any coalition government with Foster as first minister until her actions related to the RHI are examined by the inquiry.

Sir Patrick outlined the revised timetable at the latest preliminary hearing of the inquiry at Stormont.

The volume of evidence being examined – now standing at 880,000 pages – was one of the reasons he cited for the delay in commencing formal hearings.

“Clearly it is a mammoth task to review and assimilate this documentation,” he said.

The state-funded RHI was established to incentivise businesses to shift to renewable energy sources by offering a proportion of the costs to run eco-friendly boilers.

But in Northern Ireland the subsidy tariffs were set too high and without a cap, so it ended up paying out significantly more than the price of fuel.

This effectively enabled some applicants to “burn to earn” – getting free heat and making a profit as they did so.

Foster had a central role in establishing the scheme during her time as Stormont economy minister. She has insisted she acted correctly throughout.

Her refusal to accede to Sinn Fein’s demand that she step aside as first minister pending the outcome of an inquiry prompted the late Martin McGuinness to resign as Sinn Fein deputy first minister in January, precipitating the collapse of powersharing.