The crowds of up to 20 000 at the Olympic basketball and gymnastics
competitions next year probably won’t notice Australia’s most advanced solar
power generator above their heads on the roof of Sydney’s new SuperDome at
Homebush Bay. Construction of the 70 kilowatt installation is due to be
completed this week.
What is significant about the solar power system is its base
material—not the familiar, shiny blue, crystalline polysilicon most people
associate with solar cells, but matt black amorphous silicon made by Canon of
Japan. This is unexpected, because the sunlight-to-power conversion efficiency of
polysilicon—around 12 per cent for commercial cells—is much higher
than that of amorphous silicon, which can only manage about 8 per cent. So why
did Energy Australia choose a less efficient solution for the A$200
The answer, says Neil Gordon, Energy Australia’s manager of sustainable
energy, is that while researchers have concentrated on the efficiency of solar
cells as the most significant thing, “once you work it all the way through to a
full-blown power station, they might have only been working on 5 per cent of the
cost base. And halving the cost of 5 per cent doesn’t take you very far”.
The way cells are manufactured, for instance, can be more important.
Conventional polysilicon cells are produced in batches, like biscuits, then
assembled into rigid glass and aluminium frames. Canon’s amorphous cells are
deposited as a thin film on flexible strips of steel 35 centimetres wide and 800
metres long. In addition to being less energy intensive, this continuous process
uses far less material—polysilicon cells are about 300 times thicker than
amorphous cells. And at a time of rising silicon prices, that difference
Then there is the question of what efficiency really means. For the past year
at its solar farm at Singleton in the Hunter Valley in central New South Wales,
Energy Australia has operated 60 kilowatts of Canon’s amorphous panels next to
340 kilowatts of polysilicon made by the US firm, Solarex. Energy Australia found
that the output of polysilicon drops by up to 25 per cent at higher
temperatures, while that of amorphous silicon remains more constant. The net
result in terms of kilowatt-hours a year is that the Japanese modules produce up
to 15 per cent more energy.
Polysilicon panels have to be bolted onto a substructure, then individually
wired up. This is a laborious and time-consuming procedure, especially
if—as at the solar farm—you have several thousand panels to instal.
Canon modified its modules so they clip or slide into their mountings. And the
modules come pre-wired with weatherproof connectors at each end, so installing
them is simply a matter of “plug and play”. In fact, the amorphous modules take
about a quarter of the time to mount and hook up.
As a result, says Gordon, “it was cheaper to build more square metres of
Canon panels than it was to build less square metres of conventional panels”. So
Canon was awarded the contract to supply the SuperDome.
The two products represent fundamental differences in the attitude of the
suppliers. Solarex is in the energy business. Canon, however, comes from an
entirely different world. Expertise in imaging took Canon from cameras into
copiers. And the drums of copiers are often coated with amorphous silicon. By
making solar cells, Canon has an opportunity to leverage its investment in
amorphous silicon R&D.