In November of 2023, a solar technology broke another world efficiency record. The previous record had stood for only about five months—and it likely won’t be long before it, too, is outdated. This remarkable acceleration in efficiency gains comes from a special form of next-generation solar technology: perovskite tandem solar cells. These cells layer traditional silicon with materials that share a unique crystal structure.
Over the decade that scientists have been experimenting with perovskite solar technology, it has continued to set its own efficiency records, which measure how much of the sunlight hitting a cell is converted into electricity. Perovskites absorb different wavelengths of light than silicon cells do, and silicon cells account for 95% of the solar market today. When silicon and perovskites work together in tandem solar cells, they can use more of the solar spectrum, generating more electricity per cell.
Efficiency ceilings for silicon-based cells exceed 30%, while perovskite-only cells have reached experimental efficiencies of around 26%. But perovskite tandem cells have already surpassed 33% efficiency in the lab. That is the tantalizing promise of the technology: if developed at significant scale, perovskite tandem cells could generate more electricity than older solar cells at a lower cost.
But perovskites have stumbled when it comes to real-world deployment. Silicon solar cells can last for decades. Few perovskite tandem panels have even been tested outdoors.
The chemical composition of perovskites makes them susceptible to water absorption and heat-related degradation, although researchers are working to create better barriers around the panels and turn to more stable perovskite compounds.
In May, UK-based Oxford PV said it had achieved 28,6% efficiency for a commercially sized perovskite cell, which is significantly larger than those used to test materials in the lab, and plans to deliver its first panels and ramp up production in 2024. Other companies could introduce products later this decade.
Source: MIT Technology Review
