Perovskite solar cells

Changing how we make solar panels could reduce their carbon emissions

Perovskite solar cells produced at the Australian National University in Canberra

Xinhua / Alamy

Changing the way we make solar panels could reduce their carbon footprint, providing a boost to green energy.

Although solar panels are a source of renewable energy, making them has an environmental impact. Fengqi You at Cornell University in New York and his colleagues have analysed the overall environmental impact of two types of new solar panels, comparing these against panels made with crystalline silicon wafers – the current industry standard.

The team found that a new type of solar panel made from two layers of a mineral called perovskite requires a smaller total energy input and results in fewer carbon emissions. The panel, called a perovskite-perovskite tandem, contains two layers of the material on top of each other, each optimised to absorb a section of the electromagnetic spectrum.

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Perovskite solar cells have only been around for the past decade, and perovskite-perovskite tandem cells are only a couple of years old and not yet widely commercially available, says You.

His team analysed the carbon footprint and environmental impact of each solar panel over its lifespan, as well as how much time it would take for a panel to generate the amount of energy required to produce it – a measure known as energy payback time.

The silicon panels had an average energy payback time of 1.52 years, while the time for perovskite-perovskite tandem panels is only 0.35 years.

The group also calculated that in its lifespan, the perovskite tandem cell has an associated emission of about 10.69 grams of carbon dioxide equivalent per kilowatt-hour of electricity it generates, which is only 43.4 per cent of the emissions for silicon solar panels.

Another advantage of the perovskite tandem cells is that they are flexible, so could be installed on a variety of surfaces, such as on cars or bicycles, says You. “Perovskite tandems are most likely going to be cheaper than silicon,” he says, particularly in future as production increases and benefits from economies of scale.

One downside is that perovskite panels don’t seem to be as long-lasting as silicon ones, although their components could be readily recycled.

Journal reference: Science Advances, DOI: 10.1126/sciadv.abb0055

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