Just 13 years ago, engineer and serial entrepreneur John Quinn was broke and €700,000 in debt, without a job or a car, after the failure of Xonen Technologies, his hi-tech optical disc business based outside Knock.
Today, the game-changing renewable energy technology he's invented is likely to make him a billionaire in the near future and is a multi-million euro business opportunity for his company, Photonomi Energy, and one that could change the world dramatically in the years to come.
It promises - and is currently providing, through 6,000 systems installed around the world - free or nearly free heating or cooling, hot water and electricity, powered by daylight alone, for households and industrial customers. As the electric car market grows, this also means very cheap fuel for them.
Though the precise workings of the technology are protected by trade secrets, like the famous Coca-Cola formula, the business has a monopoly on an opportunity that big - perhaps only "for seven to 12 years," Quinn says, depending on whether a rival can catch up.
"I have it on good authority that some other companies have spent €250m trying to get to where we are, but they're nowhere near," says the understated first-generation Irishman, 47, born in England to parents from Co Mayo, where he grew up in Castlebar.
Business and inventiveness are in his genes. His father worked for several multinationals as a finance director and had a number of his own businesses, while in the mid-2000s an uncle in Boston invented a blood test that gives very fast results.
I asked fellow Photonomi shareholder Padraig McManus, the former ESB chief, if my understanding - though clouded by journalistic scepticism - was correct and that Quinn's invention, especially if the large scale off-grid power ambitions are realised, is as significant as it first appeared.
Has he changed the game of renewable energy, making him more of a genius than all the modern day tech geniuses we laud so much?
"If Bill Gates had told people he was going to invent what John has, people might've said he was mad," he laughed. The unspoken answer seemed to be an understandably cautious yes.
McManus continued: "Because nanotechnology - science and engineering at the atomic and molecular scale - is difficult to explain, we have to show people the savings it can make and how it works better than any other technology. It's the first one that provides such a step-change in its performance, at a level that is way above existing solar power, which has been around a long time.
"Photonomi Energy needs only daylight, and provides heating or cooling and hot water and electricity. With traditional solar you could only have heating and cooling and hot water or electricity - and the technology is over four times more efficient than some traditional solar power.
"This doesn't need a heat pump either, for cooling or heating a building, which uses electricity, so it's better than any other product. Anyone who has installed it is amazed by it. It's such a game-changer because it makes such a serious impact, on carbon emissions, on electricity and fuel bills, and in the way it operates."
Some customers to date have been early technology adopters. Photonomi's system includes an internet-connected dashboard that lets them monitor its performance, while the company can do this for them as well if they opt in, and it can alert them to any problems. After a plumber had upset the system of a customer in New Zealand, Quinn called him to inquire if everything was working okay and he fixed the problem remotely from Mayo.
Quinn's breakthrough means a €50 a year heating and electricity bill in newly built German green social housing, or perhaps €400 a year - once you've paid for the equipment - against the average €2,000 for the same bills for a three-bed semi in Ireland.
Britain's NHS - the Belfast division of which have been a customer for the past two years - had a €770m energy bill last year, and the money they could save is in the hundreds of millions, which they are in dire need of at the moment. A deal with an electricity supplier here will be announced next month and another has signed up in the UK.
Is Photonomi Energy not devouring traditional electricity suppliers' lunches?
"We enable them, by giving them new ways to sell energy. Everyone knows that selling fossil fuels is a bad business to be in. We're not their enemies; it's the exact opposite. They want as much power as they can get using our systems because we're so much cheaper."
Big users can save at least 50pc on their existing energy bills. Photonomi's technology is also not impeded by regulatory or planning obstacles that exist for solar and wind farms or installations.
Nevertheless, a paper Quinn wrote in 2014, mentioning daylight-fuelled power and the need for a "radical game-changing technology" to reduce carbon emissions from heating and electricity is striking.
He calculated that if Photonomi systems were installed in 47m UK homes, all their heating and hot water could be supplied with just one 400MW power station. The carbon emissions would be cut by 99pc and their bills would be reduced by a total of £38bn a year.
If R&D into a Photonomi large scale power plant requiring no battery storage or grid connection that is due to begin in the coming months proves successful,' that will be an even bigger game-changer.
It will have a window of however many years before a technology rival catches up to become the cheapest provider of clean electricity in the world. Could it yet become a utility giant in its own right?
In the Middle East and other drought-hit regions, new desalination plants powered by it could deliver water more cheaply than it currently costs being powered by oil or gas, or shipped in vast water tankers from nearby Turkey; and cleaner than it currently is, because of the polluted waters from where it's drawn.
Its off-grid power could boost development in Africa and the rest of the developing world too. Clean water produced easily in coastal areas, and piped to inland regions - and clean power that will not need huge batteries or pylons or underground cables to be laid.
In our many calls, texts, emails and a couple of meetings in recent weeks, the Mayo man touched on the big societal benefits of what Photonomi is doing. He emphasises plans to set up factories wherever its technology is rolled out, each employing about 700 people, with a manufacturing process intentionally designed not to rely on robots or automation, in order to create the maximum number of jobs. The location of one of these in the EU has already been decided, but not announced. The second EU one may be located here, and the company is in talks with the IDA.
The headquarters of the Jersey-registered company will be here in Ireland. Initially 120 people will be employed there, with another 1,500 installers required. But given the scale of the company's ambitions, that number could grow.
R&D is taking place here too, and a 2MW off-grid power project is planned for a university campus in the near future. The new lower tax rate on IP of 6.25pc under the 'patent box' scheme should safeguard that.
"Ireland gets the lowest levels of daylight in the world, so we test it here. Our technology works at about 80pc efficiency here, but up to 100pc efficiency in sunnier climes," says Quinn.
Speaking of which, I was particularly struck by a video clip he emailed me while he was visiting the Dominican Republic - during his frequent travels in recent weeks - where, like many island nations around the world, electricity is currently generated expensively by highly polluting diesel.
It was of a sunrise at a typical Caribbean beach that we've all seen on TV and in holiday brochures. "At two degrees global warming, this beach will be underwater, creating four million climate refugees on one Caribbean island alone. Climate change is the world's biggest man-made disaster, but also presents the biggest man-made opportunity in history," he wrote.
"Decarbonisation has been called the next industrial revolution. Trillions and trillions will be spent decarbonising the world," he added on a later call.
Earlier this week, we were warned again about the threat of rising sea levels, while an Oxford University study pointed out that energy companies can keep building new coal and gas power stations for only one more year if the world is to avoid dangerous levels of global warming. No pressure on Quinn then.
His background in electronics and finance involved 26 years in the world of semiconductors and nanotechnology, working around the world, during which he's personally invested in science and research in the structuring of molecular nano- (smaller than atom) materials for use in different technologies. "Nanotechnology has the benefit of changing all the rules of existing technologies," he says.
It's a role that also saw him set up a consultancy, Wiltshire Cayman, to which technology and IT giants turned, when the wanted huge problems quietly solved. One of these was a project in which he was a part of the team that invented a solution to enable the client, Microsoft, to put Windows 95 onto CD-Rom after Windows had previously been on floppy disks. Not quite as big as solving the world's energy and carbon emissions crisis, then.
Has he ever hit a wall - inventor's' block, perhaps - or thought of giving up the challenge during the 13 years' work that has gone into Photonomi?
"Giving up was never in my blood. I've been in innovation my whole life. You look at heat pumps, wind turbines and solar panels, which haven't advanced that much in 150 years. Compare that to car technology. That suggested I'd be able to do something. There was enough opportunity to justify the time involved. It was trial and error but science is unlocked in stages.
"Every stage highlighted there was more scope. Then I got to 83pc efficiency with Photonomi's technology and I can't see it progressing much more than that.
Is he worried about the technology being overtaken by a rival or copied by one?
"Nanotechnology is only evolving as a science. It's not taught in universities. You can't reverse engineer it. It's difficult to measure it as well. I could put our system in the hands of an expert, but it would take a very long time to figure it out. The technology is at a molecular level. We've had it globally tested in laboratories, all the certificates. It's a fully regulated market and you need government accreditation, audits of your manufacturing and there are strict standards involved. You're not allowed onto the market without lifespan testing and validation."
As a comeback from a failure in business, it may just be the most exciting Irish one yet, and perhaps Photonomi's story is only beginning.