More than 500 members of the Renewable Heat Association NI (RHANI) are seeking to have the Department of the Economy’s revised 2017 RHI regulations declared ultra vires, on the basis that tariff rates for those signed up to the original 2012 scheme could not be altered retrospectively.

Proceedings began last month and a hearing was expected next week.

However, lawyers for the Department said that an expert economic analysis submitted by RHANI had added “a new dimension” to the case.

The judge accepted that this was the case and agreed to re-list the case for a three-day hearing in October.