Farmers who took part in the RHI scheme are "on their knees" due to subsidy cuts, one participant said.
Ronnie Wells (60) breeds poultry and wants a public inquiry to restore payments he believes he is owed.
Ahead of Friday's report, Mr Wells said: "People are on their knees. They can go no further."
He is angry at the decision to cut tariffs from the government payable in exchange for energy produced, adding: "A lot have turned back to fossil fuel."
Mr Wells said he discussed the subsidy with his bank and was told it was a good deal.
He said he borrowed on the basis of the government's word and that had been reversed with the cut in tariff rates.
He added that competitor poultry farmers in England earned £18-19,000 in subsidies compared to his £1,850.
The Northern Ireland Affairs Committee of MPs has previously said some participants stood to lose hundreds of thousands of pounds in subsidies that will be paid to those using a similar green energy scheme in Great Britain.
Department for the Economy officials have said they were bound by EU state aid rules and a maximum 12% rate of return for participants.
Mr Wells added: "We were gutted when they decided to cut the tariffs. We signed up for a 20-year contract and took the figures to the bank and I was borrowing £200,000 to put in the four boilers. They looked at it and said this is the way to go.
"We got a couple of years of running at what we were promised then they just pulled the rug from under our feet.
"We are gutted - this has us struggling big time."