We didn't quite reach the third witness we'd been promised so Invest NI boss Alastair Hamilton will have to wait until tomorrow for his place in the spotlight.

And there's a return to the hotseat for Moy Park's Janet McCollum, who was last before the inquiry at the end-of-term session in June.

And, as Sir Patrick is always keen to point out, it'll be Friday so everyone will get to go home early.

We'll be here as usual at 09:45 so do join us then.

BBC News NI

An energy expert working for Northern Ireland's economic development agency identified flaws in the RHI scheme long before the problems were discovered by civil servants at the Stormont department running it.

Alastair Nicol said he consistently flagged up concerns about the initiative with Invest NI.

Image source, Pacemaker

He told the inquiry that the scheme had completely skewed the biomass boiler market.

And he said it was "not rocket science" that the lucrative subsidies on offer effectively encouraged claimants to install inefficient heating systems using multiple boilers in order to "grab the RHI money".

Sir Patrick Coghlin tells Mr Clarke that the inquiry has to ask "the most difficult and the most rearching questions" because it has "an obligation to the public".

Image source, RHI Inquiry

It's "very important to try to understand the relationship" between DETI and Invest NI about what is "potentially an enormous waste of public money", adds the inquiry chair.

He thanks Mr Clarke for his "impressive degree of honesty" in his answers to "difficult" questions.

In October 2015, just as the subsidies on offer from the RHI scheme were about to be cut, John Batch, an adviser at Invest NI, contacted DETI to say that the paybacks it would soon be offering were "not viable".

Mr Lunny questions why Invest NI was so quick to point out that the financial returns were "poor" at that point, while it hadn't made any attempt to flag up the scheme's high rewards or how it could be abused in the two years before that.

"You see that stark contrast - is there a good explanation for that difference?" he asks.

Mr Clarke wasn't involved but he says the "only explanation" is that his colleague was "looking out for his clients".

Sir Patrick says Invest NI "may have an interest" in not telling DETI about the weaknesses of the scheme and adds: "That surely cannot be right.

"Or do they simply want to say to the client: 'We're Invest NI - we will not stand in the way of getting a lot of public money'?"

At the end of July 2015, Mr Clarke drew DETI's attention to the "rush" that was on to get biomass boilers installed in businesses "just to maximise" the amount of money that could be claimed through the RHI scheme.

He says his faith in the policy behind the RHI scheme was shaken when he read an article that detailed how similar schemes in Great Britain, Austria and Germany were operating.

Image source, RHI Inquiry

They all had measures that prevented the wasteful use of heat for financial gain - the Northern Ireland scheme didn't.

But he didn't mention that factor to DETI and he accepts that he should've give more detail about what he'd heard about the high rates of return that some NI claimants were receiving.

Dame Una (below) asks Mr Clarke if he saw the RHI scheme as limiting energy efficiency.

"You read through all the reports and you take everything in the round - that's the only conclusion you can make," he says.

Image source, RHI Inquiry

When Dame Una puts it to him that Invest NI was part of the government and could see what was going on, he replies: "But we weren't delivering the scheme."

Sir Patrick suggests that it was up to Invest NI "to warn, or advise or guide a department that didn't have your expertise".

One of energy consultant Alastair Nicol's reports from 2014 concerned a commercial wood-drying operation under the RHI scheme.

He reported that the proposed system would give "absolutely no incentive to dry the wood efficiently".

Image source, RHI Inquiry

Mr Clarke says his understanding was that was acceptable under the rules and spirit of the scheme.

But in retrospect he "should have reported that to DETI".

Mr Clarke says he raised the concerns about the RHI scheme with Peter Larmour, his line manager at Invest NI.

But Mr Larmour says in his witness statement to the inquiry that "at no stage was I aware of any issues relating to the RHI scheme that were flagged in technical reports".

Image source, Getty Images

When it's put to Mr Clarke that their accounts differ, he says: "To be fair, he was aware."

Dame Una O'Brien on the inquiry panel notes that the witness sounds "very confident" that he'd told Mr Larmour about the problems and asks how often he raised them.

Mr Clarke says he can't remember but it "would've came up in general conversation".

Mr Lunny says that as an "intelligent, well educated person with some significant experience", Mr Clarke should've known that "nobody designs their scheme with loopholes in it".

"That's common sense," he adds.

Image source, Getty Images

Mr Clarke says that the view at Invest NI was that the initiative was "government policy", adding: "Therefore, why question government policy?"

But Sir Patrick points out that it "could not have been DETI's policy to have loopholes" that would lead to the "wastage of public money".

Mr Clarke accepts that he was aware in October 2014 of a "loophole" in the RHI scheme that allowed claimants to install multiple smaller boilers instead of a single larger unit and therefore benefit from much more lucrative subsidy that was on offer.

Sir Patrick says that a loophole is "something that is contrary to the intention of the scheme" and presses Mr Clarke on whether he thought DETI intended there to be loopholes in the RHI.

The inquiry chair suggests that the word "loophole" in one of the technical reports Mr Clarke received should've twigged with him that there was "something wrong", especially given that public money was at risk.

"Do you not think it might have been helpful or useful or part of your duty... to ensure that was reported back to those who had set the scheme up?" asks Sir Patrick.

Mr Clarke admits he didn't see the need to do that at the time and reflects that should've done.

The independent energy consultant Alastair Nicol told the inquiry this morning that he received no feedback from Invest NI when he submitted his reports about RHI scheme projects.

He said that all he was questioned about was his grammatical errors, not any of the issues he raised about the scheme.

Image source, RHI Inquiry

Asked by Sir Patrick if Mr Nicol is wrong in his recollection, Mr Clarke replies: "I wouldn't say he was wrong."

He says he called Mr Nicol "on a couple of occasions" to clear up technical points and spoke to the consultant in connection with about half of his reports.

There was "misunderstanding" of the RHI scheme among some of the Invest NI technical officers whose work related to the energy initiative, explains Mr Clarke.

Inquiry chair Sir Patrick Coghlin (below) is surprised to learn there was no consistent approach by the technical officers.

Image source, RHI Inquiry

The witness replies: "We didn't question each other's reports - we had our own way of doing things."

He says that while he read energy consultants' reports related to the scheme from cover to cover, two of the six officials didn't go into the same detail when considering the papers.

Businesses that approached Invest NI about the RHI scheme were "very well informed" about the energy initiative, says Mr Clarke, and he didn't need to promote it.

The firms would typically have found out about it from biomass boiler installers, other businesses or other sources, he says.

Image source, RHI Inquiry

He remembers hearing businesses telling him that they'd heard the benefits of the scheme were, as he puts it, "good in certain circumstances".

But he says it was always raised by clients and he didn't have to promote it.

As was clear in Mr Nicol's evidence today, Invest NI was told time and time again about the flaws in the RHI scheme and how it was incentivising the waste of heat.

Image source, RHI Inquiry

Donal Lunny (above), the inquiry barrister, says a key question for the inquiry will be why Invest NI - a business development agency funded by public money - did not pass those concerns on to Stormont's enterprise department.

The question is all the more important given that Invest NI is a non-departmental public body connected to the DETI.

Previous witnesses at the inquiry have said that Invest NI might have been a more suitable organisation than Stormont's department of Enterprise, Trade and Investment (DETI) to run grants initiatives like the RHI scheme.

The suggestion has been made by a number of DETI officials and Mr Clarke ventures that they are probably right that the Invest NI would've been a more natural home for the incentives-based scheme.

he says that give many staff at Invest NI have significant experience in the commercial sector they are more aware of the day to day issues facing businesses.

"To be honest about it, you're more aware of the profit motive about it," he adds.

After taking the oath, Jim Clarke, a technical adviser at Invest NI, takes his seat.

He's provided a written statement to the inquiry - you can read it here, external.

Image source, RHI Inquiry

He's been working for Invest NI for 10 years, having spent his career before that in the commercial sector.

Mr Clarke's work for Invest NI involves helping businesses to resolve energy efficiency problems and looking for ways to save them money on energy costs.

He would draw up a technical specification for the client and put that to external energy consultants, such as Alastair Nicol who gave evidence in today's opening session, who would review it, advise on it and pass it on to the client.

Image source, RHI Inquiry

The inquiry is back for the afternoon session and it's hearing from a new witness - Jim Clarke from Invest NI.

Want to watch the proceedings? Click the play button on the video at the top of this page.

Sir Patrick thanks Mr Nicol for his evidence, saying that it's "refreshing" to hear his expert view given that the work he did more or less spanned the lifetime of the RHI scheme.

The inquiry ran over a little bit there in order to get Mr Nicol's evidence wrapped up so there'll be a truncated lunch break.

It all kicks off again at 14:10 when the inquiry will be hearing from Invest NI.

Mr Nicol says he raised his concerns about the RHI scheme with DETI, the Stormont department that had set it up.

Image source, RHI Inquiry

As the inquiry heard this morning, he also told Ofgem, the scheme's administrator about how it was "skewing" the market.

He also gave lectures about biomass in which he discussed the impact the initiative was having on the market - as Mr Lunny puts it, he "made no secret" about his concerns about the RHI's flaws.

Mr Nicol emailed Invest NI's John Batch in January 2015 to accompany a report he'd written about a proposed heating system for the hotel.

He wrote that he expected his report to get "real stick" from the biomass boiler installer as he'd said the proposal was "really impractical".

Image source, PA

Mr Batch replied: "As you know sometimes the hotels just see the cash cow called pellets!!"

Mr Nicol says he discussed the proposal with hotel owner, who was "absolutely adamant they wanted to go after this RHI money" even though it meant that a large part of the car park would have to be sacrificed to accommodate the boilers.