Broccoli grown beneath semitransparent, magenta-colored CdTe thin-film solar panels used sunlight 4.5 times more efficiently than plants grown in the open field, according to a study scheduled for publication Oct. 2 in Cell Reports Physical Science.

The crop reached the same final size as conventionally grown broccoli, though it took 25 days longer to mature. The panels generated electricity throughout the 2024 growing season, offering a working demonstration of agrivoltaics — the practice of combining photovoltaic generation with crop production on the same land.

The technology at the center of the study is a customized semitransparent panel built on cadmium telluride (CdTe) thin-film photovoltaics, tinted magenta to shift the light spectrum reaching the plants underneath. The tint boosts blue and red wavelengths — the parts of the visible spectrum plants use most efficiently for photosynthesis — while the cells convert other portions of the incoming sunlight into electricity.

"The basic concept is quite straightforward," says Silvia Ma Lu of Mälardalen University in Västerås, Sweden, one of the study's authors. "The solar panels use part of the incoming sunlight to generate renewable electricity while allowing part of the light to pass through to the crops growing underneath. The broader goal is to investigate whether sunlight can be used more efficiently by allocating different portions of the solar spectrum to crop growth and electricity generation."

The shade problem

Conventional solar panels deployed over farmland give farmers a way to produce renewable electricity on land they already own, while shielding crops from excessive sun and extreme weather such as hail or heavy rainfall. The catch is optics. Standard dark-blue crystalline panels are opaque, and the shade they cast can cut yields in some crops. Semitransparent colored panels are one route around that limitation.

To test it, Ma Lu and colleagues built two 20-by-20-meter (66-by-66-foot) systems on a farm in Sweden, each fitted with magenta semitransparent panels at different transparency levels, letting through varying amounts of sunlight. A third plot of broccoli grew in full sun as a control.

The researchers chose broccoli because it is a highly nutritious crop grown worldwide and well suited to Sweden's climate. Over the full growing season they monitored air temperature, relative humidity and soil moisture, along with crop yield, nutrient composition and photosynthetic performance in each plot.

"One of the most interesting findings was how similarly the broccoli performed under the two solar panel systems despite their different transparency levels," says Ma Lu. That result matters commercially: panels with a higher density of photovoltaic cells transmit less light but produce more electricity. If crop performance holds across configurations, system designers can push generation capacity without paying a penalty in yield.

Ma Lu cautions that the findings are specific to the experimental conditions and should be validated across additional growing seasons and system configurations. "There is no single agrivoltaic design that will work optimally everywhere," she says. "More research is needed to understand how different crops respond to different system configurations and climatic conditions and to design systems that balance agricultural production with renewable electricity generation."

From prototype to farm

The systems in the study are research prototypes. Scaling to commercial deployment will require testing at larger scales and over multiple seasons, according to the authors.

If the technology does scale, the economics are straightforward. Electricity from the panels could power on-farm operations — irrigation, machinery, cooling and storage — or feed the grid, cutting farmers' electricity bills and potentially adding a revenue stream on top of crop sales.

Ma Lu and colleagues have already begun follow-up work on magenta panels, along with red and blue variants, in controlled laboratory settings free from unfiltered ambient light. Near term, she sees the prototypes fitting smaller applications: "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."

The study, "Evaluating land productivity with semi-transparent colored CdTe thin-film PV and broccoli cultivation in agrivoltaic systems," appears in Cell Reports Physical Science (DOI: 10.1016/j.xcrp.2026.103555). The next round of multi-season, multi-crop validation will determine whether the 4.5-fold sunlight-efficiency gain observed in Sweden holds broadly enough to make colored thin-film panels a standard option in agrivoltaic deployments.