Australian renewable energy researchers have set a new efficiency record for roll-to-roll perovskite solar cells, an emerging type of solar array that promises lighter and more portable PV technology than conventional silicon-based systems.
Printed onto plastic films using specialised ‘inks’ these roll-out arrays have already been given a field test on board the private Australian satellite Optimus-1, launched on Space X’s Transporter-10 mission last week.
An array of 8 ‘mini-modules’ will be tested on board that satellite as a hopeful precursor to more perovskite cells powering spacecraft in the future. In the meantime, the CSIRO, which has been developing the technology closer to home, reports in the journal Nature Communications it has achieved 15.5% efficiency at small scale, and 11% for a 50cm2 module – roughly the size of a credit card.
The typical 2,000°C temperatures required to melt silicon for conventional arrays are traded for a less energy-intensive ‘printing’ or ‘coding’ method, where plastic rolls are embossed with layers of chemical inks to form their cells. The photovoltaic layer is so thin – about a micron, the equivalent of a red blood cell – that it’s flexible and difficult to damage.
It gives promise for perovskite as a simpler, more mobile method of deploying renewable energy in hard-to-reach places.
Anthony Chesman, group leader for renewable energy systems at CSIRO and a contributor to the research, stresses their new tech won’t be competing with conventional silicon, but will offer a suitable entry point for some industries, and an opportunity for local manufacturing.
“With this flexibility – the lightweight, the rollability – we do see that this can be applied to spaces where silicone can’t be used,” Chesman tells Cosmos.
“Silicon does its job very well in the rooftop space and in the utility sector. Perovskite is more about transport applications, mobile applications, portable applications, where you really want to roll it up and tight stowage volume is important.”
Perovskite solar holds its own against more conventional silicon panels. Records in lab efficiency testing for each material hover around 25-26%, and the small-scale efficiency of the CSIRO’s experimental roll-out arrays is at the lower end of long-established silicon frameworks used for residential solar.
But the relative ease with which these perovskite arrays can be manufactured has the greatest appeal. In the CSIRO’s demonstration of its new roll-to-roll ‘printing’ method, thousands of cells could be tested quickly, and cheaply.
That’s thanks to an in-line manufacturing process the CSIRO has prototyped. Typically, the material inks printed onto plastic sheets during perovskite cell manufacture rely on the solvent evaporating before the next chemical layer can be added.
Chesman’s says the CSIRO’s new prototype will effectively allow this process to be completed on a single ‘roll’ in future, offering the hope of printing thousands of cells each day.
“Often, solar cell production is a very manual process,” Chesman says.
“But because we’re all doing it in line, using this roll-to-roll method, it can be heavily automated. And that’s where we go from an individual making 20 solar cells in a day, to this system making tens of thousands.”
Coupled with a new automated testing system, it means it would take mere minutes to analyse the quality of the printed cells.
“The capital cost for establishing the infrastructure for [perovskite] production is a lot lower, getting into the silicon game is going to cost you a billion dollars,” Chesman says.
“That has been a real impediment to Australia entering the silicon space, even though there are discussions about that happening in the future.
“So perovskites can be made with lower cost infrastructure and also have lower energy inputs as well.”
