By Phil Kreveld
Getting entangled in climate change arguments is of little value, it being the territory for climate scientists, but let’s assume that heading to zero carbon emissions is a worthy goal.
Prof Pietro Altermatt, principal scientist of Trinasolar, one of the biggest global solar panel manufacturers, opened his public lecture at Melbourne University’s Melbourne Energy Institute, with the statement that the zero-emission target for 2050 is a cop out.
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Altermatt says that to maintain present CO2 global emission rates, 400GW of solar panels aggregate capacity needs to be produced yearly—and that requires planning. To have a chance of hitting the 2050 target, we would globally have to crank out 7000GW of solar capacity per year by 2040. The point Altermatt stresses is that without production planning, we can kiss the 2050 target goodbye.
The knockers of solar might review their opinions given some stats pulled out by Altermatt. Per kilowatt hour of electricity, 1,000g of coal are required in contrast to 15g of photocell material or approximately 3kWh of energy consumed in production and an equivalent of 15g of CO2 in emissions.
His comment on Australia’s role on participating in solar manufacturing was humorous, if dismissive: “It’s like building a factory for electric torches when you need an electricity supply.”
We can take issue with this, of course, because if it comes to brainpower, we do alright. We are not short of neurons to create electrons.
Australian company SunDrive, with initial funding from the Australian Renewable Energy Agency (ARENA) developed new techniques for attaching much narrower copper contact fingers to solar cells than the existing practice which utilises relatively wide, silver-paste contacts.
Solar irradiation conversion efficiencies got a lot of attention, particularly in so-called tandem solar cells. The metallisation process surpasses the patterning and copper metallisation quality and performance of other PV manufacturers.
Dr Zhengrong Shi, the one-time billionaire and SunDrive’s first ‘angel investor’, studied under Professor Martin Green at UNSW.
There is much local experimentation with perovskites, which continue to show great promise, although commercially products are still not available. The perovskite crystalline structure can be created out of many materials and that might sound surprising as we tend to think that semiconductors with photovoltaic properties can’t be much else other than silicon.
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For example, methylammonium-lead iodide has a perovskite structure and has photovoltaic properties. The bandgap of silicon is 1.72 electron-volts. Methylammonium lead iodide has a bandgap of 1.57 electron volts—i.e., just on that basis alone you would expect it be over 9% more efficient. Very thin perovskite layers can serve in so-called tandem cells. As yet, degradation of perovskite ‘films’ over time has as yet not been solved.
Altermatt does not hold out much hope of its commercial realisation—but as is the case with technology, things can change very suddenly. That said, passivated silicon performance is already at 25% conversion efficiency. According to Altermatt, there is considerable room for improvement, particularly in hetero (multi-junction) photo cell development.
