Officials showed a 'startling lack of awareness of problem'
Former Economy Minister Simon Hamilton says officials from his department "seemed almost shellshocked by the whole RHI experience" and advised him the scheme was "very successful" on his first day in the job.
Mr Hamilton described the comment as showing a "startling lack of awareness of the problem that still remained to be solved".
He also said that, when he became Economy Minister in late May 2016, his department "was not in the best frame of mind or best equipped to deal with a problem of the magnitude of RHI" and there was a "problem with capacity".
In his witness statement to the RHI Inquiry, Mr Hamilton added: "I believe that measures to limit the cost of the RHI scheme to the Executive's budget could and should have been brought forward by the department quicker than they were.
"The failure of officials in the department to propose a robust and realistic solution much earlier in 2016 was a source of frustration for me."
Describing officials as "still grappling with firming up the quantum of the RHI cost overrun", he added: "I do recall becoming increasingly frustrated that I wasn't seeing any product of this work."
Mr Hamilton admitted that he was "frustrated at the time taken to bring forward potential solutions", but added that he "wasn't alarmed as I knew work was occurring, that it was complex, and that I had set a high standard for it".
He said he was "startled" by a proposal that departmental officials should engage in meetings with "key stakeholders" including the Ulster Farmers' Union and Moy Park prior to a consultation on introducing cost controls.
"My initial reaction was that this could be dangerous and might impede our ability to secure successful passage of any regulations through the Assembly as this would give significant forewarning to people who would, in all likelihood, oppose any changes," he said.
Mr Hamilton also revealed that he was not made aware of the date of publication of the Audit Office report until five days before its release on July 1, 2016.
And he disclosed concerns over the qualifications of the staff in his department, claiming that few officials in fields such as energy had technical expertise or qualifications.
He also said that an internal review initiated by the department, "coupled with a general sense of an impending 'blame game', had distracted officials from the job of finding a solution".
He continued: "From top to bottom, it was evident that the problems with the RHI scheme had deeply affected the department. Officials seemed almost shellshocked by the whole RHI experience in the summer and autumn of 2015 and January/February of 2016.
"They were distracted and even preoccupied with other RHI-related issues which diluted their concentration on finding a solution to the cost overrun.
"In some instances, there was a delusion that the scheme could somehow still be considered successful. Officials still had no clear understanding of key aspects of what went wrong with the scheme and there was no evidence that serious work had started in scoping out a solution."
Mr Hamilton revealed that he "took a view that there was no conflict of interest" for his former Spad John Robinson after he told him that his father-in-law was an RHI beneficiary.
He said that "at no time during my tenure as minister did Mr Robinson do anything or act in any way regarding the RHI scheme that caused me any concern or lead me to believe that he was acting in anything other than a wholly professional way in his advice to me".
But he admitted that he regretted not insisting that Mr Robinson bring the matter immediately to the attention of Dr Andrew McCormick.