Scientists have grown organic romaine lettuce under thirteen different types of PV modules, in an unusually hot Canadian summer. Their analysis showed that lettuce yield increased by more than 400% compared to unshaded control plants.
A research group from Canada’s Western University has investigated the performance of organic romaine lettuce, a heat-sensitive crop, under a wide range of agrivoltaic conditions. The test was conducted in London, Ontario, in the summer of 2025, during 18 days of temperatures above 30 C.
“Our study investigates how agrivoltaic systems can be adapted to optimize crop growth, especially under extreme heat, while contributing to sustainable energy generation,” said corresponding researcher Uzair Jamil. pv magazine.
“This becomes especially relevant in the context of climate change, where we are experiencing extreme temperatures around the world,” Jamil added. “We investigated the performance of organic romaine lettuce under thirteen different agrivoltaic configurations – ranging from crystalline silicon PV to thin-film colored modules (red, blue, green) – in outdoor stress conditions at high temperatures.”
More specifically, the experiment included c-Si modules with a transparency rate of 8%, 44%, and 69%; blue c-Si modules with transparency of 60%, 70% and 80%; green c-Si modules with transparency of 60%, 70% and 80%; and red c-Si modules with 40%, 50%, 70% and 80% transparency.
All agricultural voltaics had a leading edge height of 2.0 m and a trailing edge height of 2.8 m, and the modules were oriented southward at 34◦. Pots of organic romaine lettuce were placed under all configurations, along with three pots fully exposed to ambient sunlight without shade, which were used as controls.
In addition to measurements against the control, the scientific group compared the results with the national average yield per pot for 2022, which included fewer days with high temperatures and was therefore considered typical. These data points come from agricultural census data, which also later allowed the researcher to make national projections of their results.
“Lettuce yields increased by over 400% compared to unshaded control plants, and by 200% compared to national average yields,” Jamil said of the results. “60% transparent blue Cd-Te and 44% transparent crystalline silicon PV modules delivered the highest productivity gains, demonstrating the importance of both shade intensity and spectral quality in stimulating plant growth.”
Jamil added that if agrivoltaics were scaled up to protect Canada’s entire lettuce crop, 392,000 tonnes of lettuce could be added.
“That translates into revenues of CAD62.9 billion ($46.6 billion) over 25 years,” he said. “If scaled up across Canada, the agrivoltaic sector could also reduce CO2 emissions by 6.4 million tonnes over 25 years, making it a key player in reducing the agricultural sector’s carbon footprint.”
The results of the research work were presented in “Improving heat stress tolerance in organic romaine lettuce using crystalline silicon and red, blue and green colored thin-film agrivoltaic systems”, published in Solar energy.
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