How to get to 50% solar panel conversion efficiency? Sunovate celebrates its first demo project

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Serial renewable-energy entrepreneur Glen Ryan’s new company, Sunovate, listed in this year’s World Energy Congress SET#100, has switched on its first photovoltaic thermal (PVT) array on a house in Perth — “Early indications are that we’re getting well over 50% conversion efficiency, so that’s really exciting for us,” says Ryan.

The patented system uses air to evenly cool the panels to a level consistent with the Standard Temperature Conditions — 25 degrees Celsius — at which solar panels are tested, allowing them to constantly perform at their best. 

Sunovate’s  ‘Air-O-Voltaic’ set up also captures the heat generated by rooftop solar systems, to efficiently heat space (homes, offices) and water (hot water tanks, pools), or to integrate with heat pumps for industrial and commercial applications. 

The system is solar-panel agnostic using any standard panels fixed to a heat-exchanger layer; which rests on a cassette that incorporates the ducting to circulate air for cooling the panels, and channels collected hot air back to a centralised fan and distribution system.

“We call it value stacking,” says Ryan.

Cooling air in, hot air out

“The beauty of using air,” he told pv magazine, is that it allows Sunovate to service multiple “customers” from the one system: “We can service directly into a house with ducted warm air; we can peel a little bit of that heat off into a heat exchanger to heat a pool or a thermal storage tank or into a heat pump. And we can cascade those customers, servicing a number of them at the same time.” 

An optimisation algorithm will control distribution and storage of heat and energy depending on home user needs and commercial processes and usage patterns.

Although the initial demonstration system is a residential installation, Ryan and his co-founder Cesira Leigh have produced a small run of 50 Air-O-Voltaic units with investor funding and are in discussions with universities, a brewery, a multi-facility Australian company and mining companies, to roll out to different sites and further validate system performance.

The partners see potential in manufacturers such as dairies and breweries which use heat sterilisation processes; fodder companies that use heat to sterilise pellets; agricultural enterprises that need to dry their produce, and other heat-utilising enterprises.

Sunovate cofounders Glen Ryan, the company’s Technical Director, and Cesira Leigh, Managing Director.

Image: Sunovate

Scaling up to reduce costs

“Initially we’ll target commercial clients,” says Ryan, “to get some results at scale. 

“We’ll also be doing some more domestic demonstrators to explore various, simple ducting configurations,” to suit different roof architectures.

Sunovate Air-O-Voltaic can be retrofitted to existing residential arrays, but Ryan and Leigh are hoping to achieve scale with commercial clients in the first instance, which will bring down unit costs and payback periods.

Ryan maintains, “Unless we can deliver a return on investment of three to five years payback, it’s pointless continuing the discussion,” although he says early adopters such as councils and universities may be prepared to work on up to 10 years’ payback.

Glen and his brother Shawn were the dynamic and determined duo behind the Bombora Wave Energy Converter, which they conceived of in 2007, and which recently established European operations in Wales, in the UK, with a European Regional Development Fund grant of £10.3 million. 

The brothers are no longer involved with Bombora and Glen, a mechanical engineer who has worked in underground mining construction and wind prospecting, says his move into solar energy came about when he installed a 3 kW PV system on his domestic roof and found it never delivered 3kW, especially on searingly hot Western Australian summer days — “In the middle of summer, it was struggling to make 2kW,” he says.

“Then I started to learn a little bit more about thermal de-rating.”

Although solar efficiency at Standard Temperature Conditions is pushing through the 21% barrier at the high end of the solar-panel market, most panels are rated around 17% efficient, and in hot, sunny conditions their performance can drop back to 13-14%.

“Panels heat up 20-30 degrees in sunlight, which isn’t good for cell performance,” Martin Green, Scientia Professor at the University of New South Wales, and Director of the Australian Centre for Advanced Photovoltaics, told pv magazine earlier this year. 

Why give solar panels the chill treament?

“They prefer to operate in a refrigerator — the cooler the better,” said Green, “because the parasitic effects of the chemical reactions increase with higher temperatures, so the cooler you operate them the better.”

Green is working on methods to cool solar cells that can be incorporated in solar module design and manufacturing. Ryan and Leigh, on the other hand, want to steal the heat.

The ever decreasing cost of solar panels might lead homeowners and commercial customers to simply add panels to compensate for underperformance, a strategy that can work if you have endless roof or ground-mount space. 

However, says Ryan, if your rooftop is more space constrained, or as we want to use electricity to power electric vehicles, and generate heat for multiple purposes; and as battery-storage prices reduce and families and organisations want to solar-power their day-time operation as well as charge batteries for night-time electricity use, consumers will demand greater efficiency from rooftop solar.

Sunovate claims that its Air-O-Voltaic system improves solar panel performance by 300%. 

“At the moment,” says Ryan, “you get 100% solar energy coming into the cell which will notionally produce 15% electricity. We boost the electrical performance by cooling the panel, getting at least another 30% — that’s 45% efficiency in total as a minimum, and we expect well over 50% when we combine the electrical and thermal conversion.”

Keeping solar panels cool during operation is also expected to extend their high-performing lifespan. 

Green calculates that reducing the operating temperature of solar cells by five degrees will increase the timeframe for solar panels to reach 20% degradation by 40%.

Whether the Sunovate cooling effect will also deliver such a bonus in relation to reduced degradation is yet to be proven. “We believe it will be the case,” says Ryan.

Sunovate is capitalising on its inclusion in the WEC SET#100, by engaging in European markets where the demand for decarbonised heat is on the rise. Many would-be solutions are converging on the opportunity for producing green heat, but Sunovate’s offering is unique among them, says Ryan, who adds, “The sector is only just starting to transition, but it accounts for almost 50% of global final energy demand.”