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The solar array’s electricity output carried an annual value of about $2,694.
Photo Credit: Colorado State University
Saffron is notorious for its high price tag, and for good reason. Each crimson thread must be pulled by hand from a crocus flower, with just three threads found in every bloom. That labor-intensive process has long made the spice a difficult fit for large-scale farming in the United States.
A rooftop experiment in Denver suggests solar panels could help change that equation — at least when the panels are built with crops in mind.
In Denver, saffron planted beneath semi-transparent rooftop solar panels produced roughly twice as many flowers and dried stigmas as comparable unshaded plots, Autonoción reported.
At Colorado State University, associate professor of horticulture Jennifer Bousselot has examined how rooftop plantings perform beneath solar panels since 2007. Her lab’s master’s student, Reece Bailey, centered his thesis on saffron and later presented the results in Living Architecture Monitor.
The semi-transparent modules transmitted about 40% of incoming sunlight. Conventional opaque commercial panels, by comparison, generally let only about 10% of the light reach the plants underneath.
Because saffron struggles at either extreme, researchers have been looking for a middle ground on shade. A 2022 study from eastern Morocco put the crop’s preferred shade level near 30%, and the Colorado researchers similarly recommended panels that transmit 30% to 40% of light while being mounted six to eight feet above the growing area.
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The researchers also cautioned that too much shade is “detrimental to saffron yield.”
To gauge the business case, the researchers built a five-year budget model — while stressing that the study had limits. Their analysis used an existing 46-kilowatt rooftop system at CSU Spur that includes 4,356 square feet of space suitable for growing.
Under that scenario, the solar array’s electricity output carried an annual value of about $2,694. Using dried saffron priced at $35 per gram and adding expected income from daughter corm sales, the model estimated more than $60,000 in net returns over five years from the crop side of the project.
The authors noted that the budget was a forecasting tool and that the doubled saffron harvests were measured in shade test plots, not across the full rooftop array. They also pointed out that the first year runs negative because corms have to be bought before the crop is established.
A rooftop that can generate electricity while producing a high-value crop could help offset energy expenses and make urban infrastructure more productive without requiring additional land.
The painstaking harvest is easy to see in University of Vermont trials, where researchers counted 159 to 179 blossoms to produce just one gram of dried saffron — a reminder of why the spice stays so expensive.
Researchers and policymakers are still working to determine which forms of agrivoltaics are most effective in real-world settings. In 2023, Colorado set up a dedicated agrivoltaics funding stream through Senate Bill 23-092, and the state Department of Agriculture has distributed $1 million across 13 projects in its first two rounds.
The 2025-26 awards focused on practical questions, supporting rangeland forage work, sheep grazing on a 55-acre solar site, extension training, utility and producer interviews, and workshops for county officials.
That focus reflects the questions many landowners and utilities want answered first: whether solar sites can also support agricultural activity that is useful and financially beneficial.
What stands out in the Denver study is the panel choice, not just the crop. Semi-transparent modules remain uncommon in the U.S., yet the results indicate that selecting glass with suitable light transmission could open additional revenue from the same rooftop area.
Saffron will not be the right crop for everyone. As Margaret Skinner, the University of Vermont researcher who launched that program, told Canary Media in 2022, hand-harvesting saffron means: “You need some fine motor skills.”
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