A legal challenge to the cutting of Renewable Heat Incentive payments is to be delayed until the autumn.
The High Court was told today that an economic analysis provided on behalf of a group of boiler owners has added "a new dimension" to proceedings.
Mr Justice Deeny agreed to re-list the case for a three-day hearing in October.
More than 500 members of the Renewable Heat Association NI Ltd are seeking to judicially review a decision to reduce payments guaranteed for up to 20 years.
They claim there was no legal power for the move, and that Stormont officials must have known tariff rates for those signed up to the original 2012 scheme could not be altered retrospectively.
The botched green energy initiative was set up to encourage businesses and other non-domestic users to move from using fossil fuels to renewable heating systems.
But with operators legitimately able to earn more cash the more fuel they burned, the cost to the public purse has been projected at £500m.
The scandal led to the collapse of Stormont's power-sharing administration and is now the subject of a public inquiry chaired by retired judge Sir Patrick Coghlin.
Earlier this year former economy minister Simon Hamilton set out revised 2017 RHI Regulations as part of cost-cutting proposals.
Lawyers for the association contend this was an illegal step against boiler owners with 20-year contracts.
As part of a wider challenge they are seeking to have the move declared ultra vires, or beyond the department's legal powers.
Proceedings began last month, only to be adjourned due to issues over parallels being drawn with case law.
With the hearing scheduled to resume next week, counsel today revealed a fresh development in the case being mounted by the applicants.
Tony McGleenan QC, for the department, told the court that an expert analysis of economic matters has been submitted.
"That's a new dimension in the case... it's our assessment that I will not be able to provide a response within the present timescale," he said.
Mr McGleenan raised the possibility of his client responding with its own economic appraisal.
Both Mr McGleenan and Gerald Simpson QC, for the association, agreed that proceedings should not be put back until after the public inquiry.
They stressed the need to deal with the challenge before the current regulations expire in 2018.
Mr Simpson pledged to "move heaven and earth" to have the case ready to resume in the autumn.
"If that becomes an issue which is insurmountable we would be in a position to inform the court," he added.
Agreeing to adjourn until October, Mr Justice Deeny said: "In the light of this evaluation matter I can't hear the case next week."
