Broccoli under magenta solar panels took 25 days longer to mature in a Swedish trial
Broccoli under semitransparent magenta solar panels reached full size but took 25 days longer to mature, a Malardalen University team reports. The panels are research prototypes, and the authors say they still need testing at larger scales and over more seasons.
The Scientist · Science desk
What happened
- Plants under the panels showed a 4.5-fold increase in how efficiently they used sunlight compared with broccoli grown in full sun.
- The team built two 20-by-20-metre systems of semitransparent magenta panels with different transparency levels, plus a fully sunlit comparison plot, on a farm in Sweden.
- The custom panels were designed to generate electricity while boosting the blue and red wavelengths that enhance broccoli growth.
- Through the 2024 growing season the team tracked air temperature, humidity and soil moisture alongside yield, nutrient composition and photosynthesis.
Why it matters
- What it costs cost The grower pays in field time. A crop that sits in the ground longer delays whatever would be planted next, and that loss has to be weighed against what the power is worth on that farm.
- Who has to decide decision If broccoli does as well under the denser panels in later seasons, a grower could pick the configuration that makes more electricity without taking a larger crop penalty.
- What it limits constraint By Ma Lu's own account the prototype suits community gardens or greenhouse roofs for now, so large arable fields sit outside what this evidence supports.
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The comparison plot is the control: broccoli in full sun on the same Swedish farm, in the same 2024 season [4][5]. With it, the team can put differences down to the panels instead of the year's weather. It cannot show whether 2024 happened to suit shaded plants. Silvia Ma Lu of Malardalen University, one of the study's authors, raises the point herself [15]. "However, these findings are specific to our experimental conditions and should be validated across additional growing seasons and system configurations," she said [8].
The 4.5-fold efficiency gain needs the same care [2]. Suppose efficiency is counted against the light that reaches the crop. Then a plant that finishes at normal size on less sunlight will score well almost by construction. These plants did finish at normal size [3]. The panels also change the colour of the light [12], so some of the gain could come from colour and some from quantity. The team's next tests run in controlled lab settings, without interference from light that has not passed through the panels [9].
The cost to the farm shows up as time. The broccoli under each 400-square-metre system [17] took 25 days longer to mature [3]. The study's announcement does not report the panels' electricity output or how long the open-field broccoli took to mature. Without those two figures, the delay cannot yet be priced against power revenue or expressed as a share of the season. According to the announcement, scaled-up panels could in principle power irrigation, machinery, or cooling and storage, or supply the grid [14].
The finding I'd expect growers to care about most is a less prominent one. Conventional dark-blue panels are typically opaque and can shade some crops enough to cut yields [13]. The Swedish trial tested two transparency levels [4]. "One of the most interesting findings was how similarly the broccoli performed under the two solar panel systems despite their different transparency levels," Ma Lu said [6]. Panels with a greater density of photovoltaic cells produce more electricity, she noted [7]. The paper is due in Cell Reports Physical Science [1], and its title identifies the cells as cadmium telluride thin film [16].
What to watch
- A second growing season at the Swedish site, showing whether the 25-day delay and the similar results across transparency levels repeat.
- The team's lab tests of magenta, red and blue panels, the first data free of light that bypassed the panels.
- Published electricity yields for each panel system, the figure needed to set the delay against power revenue.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence45
- Adoption3
- Hype gap+20
- Incentives
- Not scored
- Confidence60
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
Broccoli grown under magenta solar panels absorbed sunlight more efficiently than plants grown in the open, according to a study to be published Oct. 2 in Cell Reports Physical Science.
- [2]
The crops grown with the panels showed a 4.5-fold increase in how efficiently they used sunlight.
- [3]
The broccoli under the panels ultimately grew as large as traditional broccoli, although it took 25 days longer to mature.
- [4]
The researchers built two systems measuring 20 metres by 20 metres from semitransparent, magenta-colored solar panels with different levels of transparency; in a third plot broccoli was fully exposed to the sun. The experimental site was a farm in Sweden.
- [5]
Throughout the 2024 growing season the team compared the broccoli in each plot, monitoring air temperature, relative humidity and soil moisture, as well as crop yield, nutrient composition and photosynthesis.
- [6]
"One of the most interesting findings was how similarly the broccoli performed under the two solar panel systems despite their different transparency levels,"
- [7]
Ma Lu noted that solar panels with a greater density of photovoltaic cells can produce more electricity.
- [8]
"However, these findings are specific to our experimental conditions and should be validated across additional growing seasons and system configurations."
- [9]
Ma Lu and colleagues have begun further evaluating magenta, red and blue panels in controlled lab settings without interference from light not filtered through the panels.
- [10]
The systems tested are research prototypes, with more research needed at larger scales and over multiple growing seasons.
- [11]
"Configurations similar to our prototype may currently be suitable for smaller-scale applications, such as community gardens, or for integration into greenhouse roofs rather than immediate deployment over large agricultural areas,"
- [12]
The customized semitransparent panels generate electricity while boosting blue- and red-light wavelengths to enhance broccoli growth.
- [13]
Conventional dark-blue solar panels are typically opaque and can create too much shade, reducing some crops' yields.
- [14]
If scaled up for commercial use, electricity from the panels could in principle power farm operations such as irrigation, machinery or cooling and storage systems, or be supplied to the grid.
- [15]
Silvia Ma Lu of Malardalen University in Vasteras, Sweden, is an author of the study.
- [16]
The paper is titled 'Evaluating land productivity with semi-transparent colored CdTe thin-film PV and broccoli cultivation in agrivoltaic systems'.
- [17]
Each panel system covered 400 square metres.
Sources
2 independent publishers whose own reporting we read for this story.
- phys.orgMultitasking in magenta: Colored solar panels could help farms grow crops and generate electricity on shared land
1 article · October 2, 2026
- popsci.comPink light helps broccoli grow
1 article · October 2, 2026
Topics and entities
Topics
- Thin-film solar photovoltaics
- Agrivoltaics
Entities
- Cell Reports Physical Science
- Mälardalen University