The ombudsman criticised Jackgreen's "completely ill-considered and inappropriate" marketing which targeted the vulnerable, its error-prone billing system, and its handling of an increasing problem of bad debt.

Jackgreen was suspended from the energy market and went into liquidation in December 2009, with the ombudsman still working in recent months to clean up a "very long tail" of billing and credit problems.

Elementus managing director Ashleigh Antflick was general manager of strategic operations for Jackgreen.

Elementus chairman John A. Smith was Jackgreen's chairman.

The pair are upfront about their involvement with Jackgreen, including it in their career information on the Elementus website, although Mr Antflick told The Canberra Times he finished with Jackgreen in 2006.

Elementus won a bid to build a solar farm at Uriarra with a 20-year guaranteed feed-in payment from the ACT government and is now waiting for the planning department to decide on its development application, amid fierce opposition from the Uriarra residents.

NSW Energy and Water Ombudsman Clare Petre, who investigated Jackgreen's collapse in 2010 and wrote a follow-up report in 2013, – an early warning sign about the company's problems, her 2010 report said.

That year, the ombudsman received 800 complaints, with complaints in the hundreds each year. Even since the company folded, there had been close to 2200 complaints, many from people who couldn't get a loan or a mortgage because they had been credit default listed for a Jackgreen debt. But Ms Petre said Jackgreen's records had been so poor it was in many cases impossible to verify the amount owed. She pointed to problems with incorrect account numbers (digits missing or extra), and to billing confusion, including incidents of money deducted twice, payments not appearing on accounts, the original $50 sign-up credit not being applied to accounts, and pension rebates not being applied.

Jackgreen's "completely ill-considered" marketing targeted people of low socio-economic backgrounds, including public housing estates, Aboriginal communities and other disadvantaged customers in rural and regional areas, despite green energy being a premium product appealing to the better-off. When it collapsed at least 41 per cent of its customers were on a pension or benefit.

Jackgreen had sowed the seeds of its own demise from early on through significant errors of judgment and an approach that contributed to a high ratio of bad debt, Ms Petre's report found.

Its "smooth pay" system allowing customers to pay a fixed amount per month was a failure, with the amount very roughly calculated and wrong in many cases, leaving householders owing hundreds of dollars. In some cases, the reconciliation was delayed or inaccurate.

As debts grew, so did concerns about the high rates of disconnection of Jackgreen customers, and the company's refusal to reconnect customers unless they could make substantial payments of their debt. With people on Centrelink benefit typically owing $2500 to $3500, many couldn't pay and were left without power, one customer living without electricity for six months, the report said.

In 2006, the Independent Pricing and Regulatory Tribunal found Jackgreen had signed up customers without their consent and had not fully disclosed the terms of the contracts. Jackgreen responded by sacking its telemarketer, apologising to customers and changing procedures.

Mr Antflick declined to answer questions about the extent of his involvement with Jackgreen on Thursday, saying only, "If I understand the direction you are heading in, it's not something I want to provide much comment on." He requested questions in writing, which have so far gone unanswered. Mr Smith could not be reached.

Elementus's website says Mr Antflick was a founding executive of Jackgreen. "As the General Manager of Strategic Operations, Ashleigh was instrumental in creating Jackgreen's products, middle and back office, and the listing of the business on the Australian Stock Exchange," it says.

Jackgreen now trades as Go Energy, which said neither Mr Antflick nor Mr Smith were employees, but declined to elaborate when asked whether the pair had other links to the company.

When Go Energy applied for an electricity licence in 2012, Ms Petre wrote to the regulator drawing its attention to the history of the company as Jackgreen.

A spokesman for Environment Minister Simon Corbell said significant due diligence had been applied to the solar bids. The ACT government had become aware of the Jackgreen relationship during the solar auction and sought independent advice on the matter from a financial advisory company.

"The advice satisfied the minister that the proponent had engaged experienced and capable contractors and was well progressed with financing arrangements with proven financiers." he said. "It is important to note that financiers also conduct their own due diligence of proponents in their consideration of providing finance for projects."

Based on that advice, "the minister did not consider the past association of Messrs Antflick and Smith with Jackgreen Limited to be material in relation to the One Sun project", he said. "The One Sun Capital Solar Farm is an infrastructure project that will not service a body of clients, whereas Jackgreen Ltd was a retailer which serviced several thousand customers across eastern Australia."