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Solar eclipse: Oxford firm develops world’s most efficient PV cell

Words:
Stephen Cousins

Oxford PV's perovskite-silicon cell can convert more than 29% of solar energy into electricity and, with mass production set to start next year, could play a critical role in combating climate change

Coating perovskite on silicon cells leads to jumps in solar cell performance far in excess of current best-case outputs.
Coating perovskite on silicon cells leads to jumps in solar cell performance far in excess of current best-case outputs. Credit: Oxford PV

An Oxford University spin-off company has developed the world’s most efficient solar cell, and plans to begin mass production at its European factory next year.

Oxford PV’s perovskite-silicon tandem cell was independently proven to convert 29.52 per cent of solar energy into electricity, a new world record and well above the current practical maximum of 26 per cent achievable using regular solar cells.

The power boost was made possible by coating ordinary silicon with a thin film of perovskite, a synthetic ‘wonder’ material that makes better use of photons across the solar spectrum. According to the company, Just 35kg of perovskite can generate the same power as 7 tonnes of silicon.

A 125MW-capacity production line in Berlin is under construction and, from 2022, will produce solar cells for residential rooftop panels, using manufacturing equipment from Meyer Burger in Switzerland.

Higher cell efficiencies are already being targeted and Oxford PV has a roadmap to achieve at least 33 per cent efficiency in the short-to-medium term, and potentially 39 per cent in the longer-term.

Oxford PV's chief technology officer Chris Case told RIBAJ: 'The 29.5 per cent achieved using our tandem solar cell is more efficient than silicon alone will ever get in production; it's more efficient than the most efficient solar cell material in the world, gallium arsenide. What's more, it represents just the beginning of a journey and we expect to extend performance well into the 30s.'

 

  • Perovskite-silicon panel performance is expected to be up to 20% better than existing panels
    Perovskite-silicon panel performance is expected to be up to 20% better than existing panels Credit: Oxford PV
  • Currently based in Oxford, production is moving to Berlin, using Swiss Meyer Burger solar panels.
    Currently based in Oxford, production is moving to Berlin, using Swiss Meyer Burger solar panels. Credit: Oxford PV
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More efficient and affordable renewable technologies are critical in the fight against climate change, and solar is predicted to provide 50 per cent of global electricity generation by 2050.

The key benefits of using perovskite are its light-converting efficiency, low cost and relative abundance as a material. According to Case, there’s enough in the Earth's crust to deliver terawatt-scale PV to transform the world’s carbon footprint.

Oxford PV had originally intended to use perovskite in a transparent Building Integrated PV (BIPV) but despite significant research and development, the work was suspended due to challenges around market demand for the tinted glass and scaling up for manufacture.

Instead, the company decided to switch to augmenting regular silicon cells with perovskite to boost efficiency.

'After 65 years, silicon has hit a wall that can't be climbed using the same technology,' says Case. 'But perovskite is particularly good at converting photons to electricity in the [blue] colour range, and the silicon solar cell we developed is particularly good at taking advantage of perovskite. There's innovation in the architecture of the solar cell and in the materials engineering.'

Homeowners may end up paying more for the panels, due to the extra engineering involved, says Case, but a typical rooftop will generate 20 per cent more power from the same number of cells resulting in longer-term savings on energy bills.

Since rooftops have a fixed size, the system is expected to attract customers keen to maximise output for their available surface area. 'If your dream is to get more power, then you need to have a technology like ours,' Case concludes.

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