Perovskite-silicon tandem solar cells are a leading candidate for the next leap in clean energy. But new research, published in eScience Energy, indicates that lab results alone do not determine how well these panels perform once they are operating outdoors.
The researchers found that fluctuations in sunlight outdoors can reduce the power these panels deliver. Still, they generated more electricity per unit of land than conventional silicon modules.
Here's what to know
As Mirage News detailed, the study examined two-terminal perovskite-silicon tandem solar cells.
These kinds of cells stack two light-absorbing materials to capture more sunlight than standard silicon panels can on their own. In a two-terminal tandem cell, the two sub-cells are placed in series, so the device is limited by whichever current is lower at a given time.
Cloud cover, local atmosphere, seasonal changes, and geography can all alter the mix of wavelengths in sunlight, and those shifts can throw the two sub-cells out of current balance.
In lab testing, the researchers measured current mismatch at 4.98% in blue-rich light and 4.32% in red-rich light. They then used long-term spectral data from four places — Haikou, Yancheng, and Daqing in China, plus Albuquerque, New Mexico — to estimate how those shifts could affect outdoor performance across different regions.
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Across those four climates, spectrum-related energy losses ranged from 0.77% to 3.25% per watt compared with single-junction silicon. But the tandem cells produced 8.74% to 11.16% more annual energy yield per unit area.
More background
Accurate forecasts help solar developers estimate how much electricity a system will actually generate over the course of a year. This shapes project pricing and panel placement.
If tandem panels can produce more electricity from the same parking canopy or solar farm footprint, people may be able to get more clean power without needing additional land.
That could be especially valuable in crowded or high-demand areas, where space is limited and the economics of each project matter even more.
Adopting solar power can also help reduce harmful air pollution from energy sources like coal and natural gas, improving air quality and benefiting public health. And if projects can deliver more electricity efficiently, utilities and companies may have a stronger incentive to expand clean energy capacity in ways that can help stabilize energy costs.
What's being done?
The researchers proposed a more practical way to measure this challenge in the field. They developed a simplified approach for situations where full spectral measurements are unavailable, using UV irradiance and global horizontal irradiance.
That could make it easier for developers to determine whether tandem cells are a strong fit for a specific climate before deploying them at scale.
In favorable regions, better land use and direct-current balance-of-system savings could reduce the levelized cost of electricity by up to 1.59%. The researchers added that, under "optimal spectral conditions," this could result in "a potential maximum price premium of 7%."
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