Inquiry counsel Donal Lunny is keen to launch into another document from his vast collection, but chair Sir Patrick Coghlin intervenes to point out that it's 17:30 and time to wrap it up for the day.

Join us again tomorrow for day seven of the RHI Inquiry live from the Senate chamber at Stormont.

The fun starts at 09:45 GMT - see you then.

BBC News Northern Ireland

Only one-and-a-half staff were working on the RHI scheme for much of the first year of its planning by DETI, the inquiry heard.

Image source, Press Eye

Inquiry chair Sir Patrick Coghlin said it was "hard to swallow" the contention that that number was adequate to run what was a highly complex and ultimately flawed project.

The inquiry also heard that Northern Ireland did not participate in the Great Britain version of the initiative because of worries of "over-incentivisation".

A "final draft report" between CEPA and DETI on 31 May 2011 revealed that none of the renewable heat initiatives that were being considered for Northern Ireland would not have delivered the 10% target for green heat production by 2020.

Image source, Getty Images

It also determined that an up-front grant scheme - which was not adopted - would deliver the best results in terms of cost benefit.

The eventual RHI scheme was, of course, an ongoing subsidy scheme, but the "final draft report" did not conclude that it was a better option than a grant fund, Mr Lunny observes.

CEPA provided a first draft report on 31 March 2011, and Mr Lunny refers to a follow-up email from DETI's Peter Hutchison to Ian Morrow of CEPA on 6 April that year.

Image source, RHI Inquiry

In this document under the heading of "Risk", Mr Hutchinson states: "Need a more detailed section on risks as per stage six of appraisal guidelines.

"Risks to be considered would be low uptake, rising renewable prices, low resource, low gas or oil prices, damage to other sectors, risk of perverse incentives, inadequate or overly generous support levels, etc."

CEPA spent much more time on its work for the department than it charged for, it claims.

In its evidence to the inquiry, it says its staff spent 131 days working on it and puts that time at a cost of more than £148,000, which is said is "much more than that £50,100" it received from DETI.

Image source, Getty Images

CEPA said that was in no small part due to having to address "the many questions and comments raised by DETI".

"This demonstrates the significant level of committment to support DETI," adds CEPA.

Mr Lunny says CEPA has provided the inquiry with "tens of thousands of pages" relating to its work on the 2011 report.

Mr Lunny turns to the subject of Cambridge Economic Policy Associates (CEPA) and AEA Technologies, two companies that worked together on an economic appraisal of the proposed RHI scheme in spring 2011.

CEPA's remit was to make recommendations based on evidence and economic analysis about the "most cost-effective structure" for a scheme to increase renewable heat production in Northern Ireland.

AEA was essentially a sub-contractor to CEPA with a defined technical role.

In her submission to the inquiry, DETI's former energy division director Fiona Hepper says "resources were limited" and her staff were "working extremely hard to deliver across both domestic and non-domestic heat matters".

She says she was successful in obtaining extra staff to work on renewable heat but adds: "I appreciate that given the nature of the work in energy at that time was such that it would have continued to expand to soak up any amount of resource."

Image source, RHI Inquiry

Mr Lunny compares this with the staff resource available at DECC, where the Great Britain RHI scheme was included in the government's "major projects portfolio".

He says the inquiry will have to consider DETI's "rationale for the stark difference" in its staffing on the RHI scheme with that of DECC.

It is "difficult to swallow" that only one-and-a-half staff at DETI "who don't have any particular expertise" were involved in the set-up of the RHI scheme, according to inquiry chair Sir Patrick Coghlin.

He points out that the project initially had £25m of funding and may have "given rise to all sorts of uncertainties".

Image source, RHI Inquiry

"Resources seem to be terribly important here," he adds.

Mr Lunny informs the inquiry that that DECC - the government department that ran the Great Britain scheme - had 77 staff working on it at one point.

A bespoke branch set up within DETI in May 2011 to deal with the RHI scheme initially consisted of only two people.

Mr Lunny explains that it was made up of Joanne McCutcheon, who worked part-time and headed the branch, and Peter Hutchinson, before - a small number of others staff were added in 2012.

Image source, Getty Images

The inquiry will have to consider how adequate those resources were for the running of the RHI project, says Mr Lunny, and that is an issue that crops up throughout the documentary evidence and witness statements.

He quotes a statement from civil servant Shane Murphy, who says DETI's policy work was done "on a shoestring" compared with UK government departments.

And David Sterling, the then DETI permanent secretary, stated in 2011 that the department "faced a stiff task keeping pace with the energy agenda in Whitehall".

Farmers were demanding for an renewable energy initiative for some time, the Ulster Farmers' Union told DETI in 2011 as part of the public consultation on the RHI scheme.

DETI officials were in "reasonably regular contact" with their colleagues in Stormont's agriculture department long before the scheme opened, says Mr Lunny.

Image source, Reuters

And they were "educating" the agricultural sector about the likely details of how it would run as far back as a year before it finally launched, holding presentations on the subsidies on offer.

Mr Lunny asks whether DETI considered the likely impact of its promotion on the eventual uptake of the scheme, and in particular whether there was a disproportionate uptake among agri-businesses that had a high requirement for heat, such as poultry or mushroom farmers.

The Department of Agriculture and Rural Development (DARD) was also involved in renewables initiatives, as evidenced by the submission to the inquiry by Noel Lavery, its permanent secretary.

Mr Lunny gives the example of a DARD scheme for the growing of biomass fuel crops, starting in 2007.

Image source, CAFRE

He goes on to observe that CAFRE, a training and research branch of DARD, had included information promoting RHI at 58 events from November 2011 to October 2015.

Inquiry chair Sir Patrick Coghlin intervenes to point out that CAFRE was "carrying out promotional training events where the Department of Energy (sic) were trying their best to reduce the attraction of the scheme".

"So it seems," says Mr Lunny.

Witnesses to the inquiry have raised concerns over whether Stormont officials understood the budgetary responsibility and cost implications when they decided to go ahead with an RHI scheme specific to Northern Ireland, says Mr Lunny.

He points to a statement from Mark Coburn of the consultants Cambridge Economic Policy Associates (CEPA), who said that managing a smaller budget subject to potential large changes in accreditation levels was "always going to be more challenging than a larger one".

Regardless of the problems that arose with its own RHI scheme, Northern Ireland would have been better off in the Great Britain initiative, Mr Coburn argues.

Mr Lunny then takes the panel to a judgement from the Court of Appeal of England and Wales from 25 January 2012, saying that DETI may have been able to assess it "to learn about what went wrong" with the Feed-In Tariff (FIT) scheme, which was referenced before lunch.

He quotes from a summary regarding the FIT scheme: "The adoption of solar PV by communities and the public has been unexpectedly successful."

Image source, RHI Inquiry

"The cost of installing solar PV systems had fallen substantially from about £13,000 to £9,000 for four kW".

The document continues: "The secretary of state was concerned that solar PV generators would be overcompensated", and that would limit the funds available for other technologies.

"Familiar issues, you might think," comments Mr Lunny.

There were a number of energy initiatives run by DETI in Northern Ireland before the RHI scheme, and Mr Lunny runs through some them.

One of those was the Northern Ireland Renewables Obligation (NIRO), which imposed on all suppliers to source a specified share of the electricity supplied to consumers from renewable sources.

That could be achieved by submitting renewables obligation certificates to the Gas and Electricity Markets Authority (GEMA) obtained by self-generation of renewable electricity, through purchasing it from other renewable energy producers, or by making a buy-out payment to the authority.

These certificates are known as NIROCs and when the scheme was introduced each unit of electricity received one NIROC, no matter what technology was used to produce it.

However, in 2009, banding of technologies was introduced to reflect the different costs of the various technologies that were at different stages of development and that meant that different technologies received different levels of NIROCs depending on their place in the banding.

Another scheme - Reconnect, which ran between 2006 and 2009 - was expecting 375 applications, but instead there was a total of 1,240 biomass boilers installed on the scheme.

Mr Lunny asks whether DETI learned from its experience in running previous schemes.

There is a "thicket of complexity" to the RHI scandal, says Mr Lunny, as he lays out when he's about tell start telling the inquiry.

He says there will be a need to go into considerable detail in his presentation in order to "expose some sometimes simple truths behind the issues" that led to the scheme turning into the disaster that it became.

Image source, RHI Inquiry

"Some points are so important that they bear repeating," he adds.

"Certain truths and certain knowledge gaps will only be plugged during the oral evidence that we hear."

After more than a week's worth of background and overviews about the RHI scheme, we move to the first of four phases of this inquiry.

This part concerns the original design and implementation of the RHI scheme in Northern Ireland, and inquiry counsel Donal Lunny (below) steps up to the platform.

Image source, RHI Inquiry

His presentation was due to have started this morning but the inquiry's business is already falling behind schedule - and this is only the sixth day of hearings that are expected to run well into the spring of 2018.

Sitting times were extended yesterday and today, and inquiry chair Sir Patrick Coghlin says there'll be an earlier-than-scheduled start tomorrow, too.

Mr Aiken wraps up - for now - his summary through the early stages of both the Great Britain and the Northern Ireland RHI schemes.

After lunchtime, we'll hear from inquiry counsel on the specific origins of the Northern Ireland - proceedings resume at 14:05.

DECC was anticipating that would significantly underspend on its budget for the RHI scheme until the 2014-15 financial year, and its proposed cost control measure was therefore highly unlikely to be implemented.

But Mr Aiken explains that DECC was looking to put it in place because, as it said in its consultation document, it had learnt lessons about "rapid upsurges in uptake" from a previous subsidy scheme.

Image source, Getty Images

That scheme was the Feed-In Tariff scheme, which encouraged the use of small renewable electricity generation systems, such as solar panels and wind turbines.

Mr Barker, the then energy minister, said that scheme had failed to anticipate the development of industrial-scale installations, and DECC concluded that it was "crucial that we take a more responsible and efficient approach to public subsidy".

Mr Aiken asks: "Did any of this learning make its way to DETI?"

In March 2012, a consultation by DECC on the addition of cost controls in the Great Britain RHI scheme was opened, proposing a temporary suspension of the initiative if estimated spending reached a level where it could go beyond the allocated budget.

That would be done to allow time to introduce digression into the scheme, gradually lowering the subsidies on offer as the scheme grows.

In a foreword in the consultation, the then energy minister Greg Barker (above) said the cost control was needed to ensure the "long-term future of the RHI" and keep its spending within its limits.

Uptake was low at the stage, he acknowledged, but consideration had to be given to cost controls early in the lifetime of the scheme as a fallback should it later take off.

Mr Aiken says DECC was getting prepared for a potential increase in demand, and the inquiry will need to consider whether the then DETI minister was informed that DECC was considering cost controls measures at that point.

Mr Aiken now refers to a submission from Ms Hepper to Mrs Foster, the then DETI minister, on 16 March 2012 seeking approval to proceed with the Northern Ireland RHI scheme.

He says it should be noted that "the submission would not be signed off by the minister until 11 April 2012".

The word "content" can be seen on the document in handwriting.