When sitting on a train in Scotland, scientists Dr Klaus Weber and Professor Andrew Blakers from the Australian National University had a ‘Eureka’ moment that was set to revolutionise the solar power industry.Weber and Blakers were killing time en route to a conference in 2000 when they first discussed the concept of creating SLIVER solar cells.

As the name suggests, SLIVER cells are literally slivers, cut from traditional silicon wafers. These silicon wafers are around 10cm in diameter and 1mm high. As the wafers are “sliced” – through a chemical process that creates grooves in the wafer, which later enables the slivers to be separated from each other – the result is a SLIVER cell around 8cm long, 1mm wide and 50 microns thick.

This innovative approach to silicon wafers has profound implications for the solar industry. While the benefits of using solar energy are obvious, the costs associated with it have been an obstacle for widespread use.

The ANU’s Centre for Sustainable Energy Systems has developed the technology in association with Origin Energy. SLIVER technology was overall winner of the 2006 Sustainable Cities Award.

According to the Centre’s Manager Ray Prowse, SLIVER technology results in better use of the silicon, meaning less waste. “The big advantage of SLIVER is that it uses as little as one-tenth the amount of silicon compared to conventional models to give the same output,” he says. “Our driving force is to produce electricity cheaper with solar technology.”

There are various innovations associated with SLIVER technology that are helping to achieve this aim. Because of the way the sliver is cut from the silicon wafer, it has a bifacial response. This means it can absorb light from either side and can be “sandwiched” in between two glass panels, thus maximising its capacity for light collection.

Furthermore, if the SLIVER cells are spaced a short distance apart, not only does that mean that fewer cells are needed to cover a panel but also the light that comes in through the gaps hits the reflector and can bounce back into the SLIVER cell. “All other traditional solar cells have a grid on the front to collect electrons generated by the cell and a solid backing,” says Prowse. “So they can only collect light from one side. If you use panels made from SLIVER cells in a window, you can get light from both the outside and inside.”

The thinness of the SLIVER cell also means it’s flexible, and can therefore be used in curved glass roofs or windows, opening up a plethora of architectural applications.

Efficiency and resilience

The SLIVER cell is also shade tolerant. “This is an enormous advantage,” says Prowse. “In conventional solar modules each of the regular 36 cells is connected in a series, one after another in line. This means the electrical current flowing through the module flows through every one of those cells. If you shade any one of those 36 cells – say because of a leaf or a bird dropping – you effectively cut out the electricity in the whole module. The output of the module is dependent on the worst-performing cell.”

Prowse says that SLIVER cells are connected in series to create sub-modules about the size of conventional cells. These sub-modules are then connected in parallel to complete the module. “If you shade any of the sub-modules, you only lose that sub-module because it’s connected in parallel,” he says. “The other advantage of the SLIVER cells is that they are quite tolerant of the high temperatures that traditionally have adversely affected solar panels. It’s ironic; you think that if you put it in the sun, it will hum. But as the internal temperature of the cell increases, the output voltage actually decreases. Because SLIVER cells are so thin and can be spaced apart from each other, they are good at dispersing heat, so the internal temperature remains lower than that in conventional solar panels.”

Origin builds manufacturing plant

Developing SLIVER cells has largely been possible because of funding and collaboration with Origin Energy, who own the intellectual property to the technology. Origin has built a pilot manufacturing plant in Regency Park in Adelaide.

“We are keen to continue to work with Origin on improvements and to develop subsequent generations of the technology,” says Prowse.

Prowse believes the application of SLIVER technology can have a significant impact on power generation in Australia and overseas. “When you use this, you don’t need a power plant, you don’t have transmission losses, and you can put it on your rooftop and it can go straight into the windows of your house.”

www.sliver.com.au