The 2014 decision, which ended a major stoush with Uriarra residents over the site of the Elementus solar farm, appears to have been made with virtually no documentation, and just one 18-month-old valuation.

In response to a freedom of information request for documents relating to the decision to buy the block from Actew, the agency listed just five documents, none of which set out a detailed reason.

It said that because one of the board members had declared a conflict of interest some of the documents "that would normally be created ... do not exist in this instance".

The board member was Chris Purdon, and while the nature of her conflict is not disclosed, the company she owns with husband Rob Purdon was contracted by the solar farm during development.

The agency said Ms Purdon's conflict "necessitated in camera discussions and the recording of key decisions only".

It released handwritten notes of a board meeting of December 11, 2014. The scant notes only have the words "actions" and "pursue Williamsdale" - presumably recording a decision to go ahead. The final board minutes contain only a dot point saying "two confidential items were discussed in closed session and not recorded".

Whatever briefing the board received appears to have been verbal with no indication that papers were prepared outlining the detail of the block or the reasons for the purchase.

Asked why a board member's declared conflict would result in a decision to produce no documents, agency deputy chief executive Neil Bulless said the decision to omit the conflict and decision from board minutes had been wrong and practices had since been changed.

"This omission was considered at the time, as a way to present the minutes to board members in order to avoid sharing with Ms Purdon details of the discussion given her notified conflict declaration. In hindsight, this was an error and arrangements have since been put in place to avoid such omissions from minutes," he said.

His explanation doesn't explain the wider lack of documents. The five documents listed in response to this newspaper's freedom of information request were:

In that brief, Mr Dawes said he had completed the assessment and made an offer to Icon (previously Actew) for $3.1 million plus GST. He was satisfied the purchase met the criteria set out in policies covering land acquisition.

He told the board he would offer up to 50 hectares (of the 425 hectare site) to the solar farm, with the possibility of a Commonwealth agency buying up to 200 hectares, and consideration of the rest being used "as a rural residential estate".

It appears there was no business case. Government policy requires a business case if a commercial outcome is sought from land; if the outcome is not commercial the costs must be "reasonable and not onerous".

Asked about the lack of a business case, Mr Bulless said Mr Dawes had given "a verbal briefing to the board providing the rationale for the acquisition, being a transaction between government entities. Approval to pursue the acquisition was made on the basis of that advice."

Asked why there were no other documents setting out the rationale, including to government, Mr Bulless said, "The Minister for Economic Development [Andrew Barr] was briefed on the LDA Board-approved decision to purchase the land in March 2015."

The decision to buy the land came amid a stand-off with residents of Uriarra village. Looking for an alternative site, the government announced in March 2015 that the solar farm would move to Williamsdale.

At the time, Mr Dawes said, the board "saw it as an excellent strategic purchase".

The 2013 email identified as the first mention of the purchase is from Actew business development manager Duncan Edghill on August 23 2013, when he asked the agency for a meeting to discuss Actew's "parcels of land in Williamsdale". "We'd be interested in exploring development options for those lots," he wrote. The valuation pre-dates that email.

The email came four days after the government announced that Elementus had been successful in the solar auction for public funding. Actew also put in a bid in that auction to run a solar farm on the Williamsdale site but missed out.