Up to 10,000 jobs could go in Northern Ireland as a result of the decision to end subsidies for renewable energy.
Action Renewables Director Michael Doran told the BBC’s Inside Business programme that some people who had invested in wind turbines faced massive losses.
Government-backed incentives for wind power and other energy sources are due to end within 18 months.
Mr Doran said jobs would be lost unless a replacement incentive was introduced: “My guess is, if there is nothing to replace the Renewables Obligation whatsoever, it would lead to between 5,000 and 10,000 job losses within Northern Ireland - it’s significant.”
Last week, it was announced that the current subsidy system for on-shore wind energy is set to end next April, a year earlier than planned.
Stormont’s enterprise minister Jonathan Bell started a two-week consultation on the proposal.
Herald Express recently reported that thousands of solar jobs in the South West could be lost because of the proposed 87% cut to the Feed-in Tariff, according to Solar Trade Association (STA) analysis.
The Department of Energy & Climate Change proposed at the end of August to cut the tariff paid for electricity generated by rooftop panels from 12.4p to 1.6p.
The move will put under threat most of the jobs that are related to solar energy, the STA warned.
The association said that the number at risk in Devon is 264 and in Cornwall is 304.
The losses relate to those who work directly in the industry or in the supply chain.
One company boss said that small and medium-sized firms would be hit at the expense of state-owned foreign utilities.
Across the South West there are currently 90,832 solar homes and 3,168 big solar rooftops on schools, warehouses and other commercial buildings.