Achieving Robust Solar Panel Construction with 3D Solar Photovoltaic Leaves

Interview conducted by Kris WalkerJun 25 2013

The great evolution of solar panel technology is something that offers welcome relief within our carbon constrained society. With solar technology becoming more commercial, the advantages are there for all to see but so are the disadvantages.

What's crucial, to achieving robust solar panel construction, is the pursuit of the optimum arrangement of solar panels.

Research from the Australian National University has achieved just this with the development of solar panels in a 3D arrangement. In this interview, Ross Egar, PhD at ANU talks to AZoCleantech about this innovation that could change the construction of solar panels.

Mimicking nature’s leaves to create this 3D PV solar panel arrangement is something very unique, where did this innovation come from? And can you describe the design and production process?

The mindset of engineers and artists is generally thought poles apart but Nature regularly inspires both to innovate. Less poetically with my 3D PV arrangements it was only in retrospect that I drew parallels with nature – that’s to say, trees haven’t evolved into heliotropic flat photovoltaic membranes, which in benign circumstances would exploit solar energy best. Trees have developed three dimensional arrangements of leaves to minimise thermal stress, wind load and other environmental risk factors.

In contemplating the same environmental risk factors affecting solar panels I thought vents between panels would be a good thing but didn’t like increasing the envelope of installations too much – it was then it occurred to me side-by-side panels could be moved up or down to make vents arbitrarily large.

A 3D PV panel arrangement can be commercially competitive (but not optimised) using stock standard commercial panels. I have researched the separation between double layers and panel numbers to reduce peak wind loads when using commercial panel sizes. That involves using supercomputers for the numeric analysis of wind loads because each configuration and orientation of an arrangement requires months of processor time to evaluate otherwise.
Only scale models of 3D panel arrangements have been produced in order to physically test the predictions of analyses. This has been done successfully. A prototype 3D solar tracking system integrating at least 18 commercial panels should become a reality sometime next year.

What would be the difference in terms of traditional solar panels and 3D solar panel arrangements? And how would this benefit the consumer?

Presently solar panels are all installed side by side as seen on rooves. The simplest 3D solar panel arrangements have two overlapping partially filled layers. The panel positions of each layer are complementary so that, when moved as an ensemble to track the sun, the shade from front layer panels falls between rather than on rear layer panels.

The benefit to the consumer comes from a reduction of structural and thermal stresses on photovoltaic systems.

Wind horizontal and vertical-lift forces on solar tracking systems can be reduced by 20% and 30% respectively using a double layer 3D PV arrangement with an inter-layer distance of about half the length of the constituent panel’s diagonal. In broad terms an existing tracking mechanism should be able to integrate 20% more photovoltaic surface and lighten its foundations by 8% by switching to a 3D panel arrangement.

As well as shortening the lifetime of solar panels by years, during summer thermal stresses routinely reduce the peak electricity of poorly ventilated solar cells on rooftops by over 15%. The 3D panel arrangement is well vented and expected to halve a cell’s conversion efficiency losses due to thermal stress, and that’s when it needs to be working best, when the highest levels of sunlight are present.

The economic benefit of 3D solar panel arrangements due to the combination of structural and thermal advantages described should be at least 9%.

Panels in layers elevation 15 degrees to horizon. Image Credit: ANU.edu.au

The 3D layer structure is unique, how flexible is the technology in terms of its consumer applications? For example, can they be scaled to fit all homes, office buildings etc?

The 3D layer structure can only be used by a system that tracks the sun so in that sense it is less flexible. On the other hand only a very small minority of us have the roof, orientation and lack of shade necessary for efficient solar photovoltaic systems. Due to the way cities have developed and their shade and height restrictions it is unlikely tracking systems will become ubiquitous in urban settings. On the other hand all consumers will benefit from innovations that make ownership of solar power sources more accessible.

A major contributor to solar accessibility will be the development of specialist parks around city fringes that lease sites to owners for grid connecting their solar systems. 3D solar tracking systems will on average use six times less photovoltaic area than low cost non-tracking systems and are more compatible with dual land uses including agriculture. This means solar parks can offer owners the most cost competitive location in terms of land rates, sunlight and subsidies for their investment dollar on a global basis. There is no physical reason a Londoner should not put their solar tracker in Valencia for example if only sunlight quality mattered. By installing common infrastructure solar parks also minimise the cost of having services such as internet to monitor private electricity production or security and maintenance options.

This technology represents outstanding research from yourself at ANU, what is the vision here? Where do you see this technology in the next five years?

Solar energy is unique in its ability to be scaled to any need and that’s what’s really driving this sector. There is more than ten thousand times the energy on earth in sunlight than in all electricity grids combined and individuals can choose the photovoltaic capacity they need or within their means because it works with equal efficiency whether powering a watch or town.

The advantage of 3D layer technology in the solar energy sector is qualitatively easy to recognise but building a system that optimises the reduction of structural and thermal stresses requires supercomputer use, original design and research capacity. While analysis and wind tunnel tests of the 3D double layer structure have shown its advantages are of the magnitude claimed technology investors from business and government are risk adverse and waiting for market ready product first. That’s two years away using my personal resources. The approach of common investors reduces their risk but sees opportunities lost as well as costing valuable years of profit when a patent’s value ends instead of reaching its highest levels.

In 5 years I expect there will be parks on city fringes installing garage sized 3D solar units each generating in the order of 20 to 30kW hours of electricity per day which is about the minimum a household needs. None of us will be chained to a particular house to individually generate the renewable energy equivalent of what we use.

Reduced drag surface of 7x7 Double Layer Array - Image Credit ANU.edu.au.

For students looking to study environmental technology at University, why is ANU the place to be?

The ANU has a large solar energy research group focused on the two areas of photovoltaic cells and solar-thermal technologies. Located in central Canberra, big city issues like air pollution, noise and traffic congestion are absent. The wildlife on campus also offers something unique with daily views of beautiful parrots, ducks, rabbits and kangaroos occasionally. It is a place where students can really focus on study.

In my research area of fluid dynamics the ANU is small and I go to the University of Sydney 300km away to run wind tunnel experiments. On the other hand the ANU provides a significant element of the National Computing Intra-structure in Australia and fluid dynamic analysis, which consistently pushes the limit of computing resources available, is facilitated here.