The Assembly will today vote on a controversial proposal to end the Renewable Heat Incentive (RHI) scheme here.
In a shock announcement earlier this month, Enterprise Minister Jonathan Bell said the financial support programme for green energy was to be axed almost immediately because of budgetary pressures.
He then announced it would be extended until the end of February, after pressure from MLAs, companies and farmers.
Now, John Martin, chairman of suppliers group Biomass Energy NI (BENI), has said the cut-off "is like a guillotine to the renewable energy sector".
"We are extremely disappointed that DETI has not managed the policy and applications in such a way that would provide longer term certainty to investors and developers in the market," he said.
"Instead, we had positive changes to the RHI scheme announced in September 2015 which came into effect in November 2015. This resulted in a doubling of applications in a single month to November 18 compared to the previous three years."
He said the short extension was of "very little comfort to our members and other sector investors".
Patsy McGlone MLA, the SDLP chair of the enterprise committee, said the minister had created a crisis.
The scheme is now over budget by at least £30m after a surge of applications.
Ulster Unionist MLA Adrian Cochrane-Watson accused the minister and his officials of "incompetence on a huge scale".
Firms that manufacture and install the equipment claim they will lose millions of pounds, and that up to 2,000 jobs could go.