Swedish researchers have successfully combined solar power generation with broccoli cultivation on a single plot of farmland. The semi-transparent purple solar panels allow only the light wavelengths needed for photosynthesis to pass through while generating electricity, boosting land-use efficiency by 18%.
A research team led by Professor Pietro Elia Campana at Mälardalen University published findings in the international journal Cell Reports Physical Science showing that broccoli grown beneath semi-transparent cadmium telluride (CdTe) thin-film solar panels absorbed sunlight more efficiently than in open fields. This marks the world’s first demonstration that wavelength-selective solar power generation can simultaneously produce electricity and grow crops in ordinary open farmland.
Conventional silicon solar panels are dark blue and opaque, casting shade that makes crop cultivation underneath difficult. The purple semi-transparent panels developed by the research team transmit blue light (400–500 nm) and red light (600–700 nm)—the wavelengths chlorophyll uses for photosynthesis—downward to the crops below. The experimental systems each covered approximately 20 square meters, larger than previous studies using the same technology.

▲ Chlorophyll absorbs light most strongly in the blue (400–500 nm) and red (600–700 nm) ranges, while reflecting relatively more green light (500–600 nm). This is why leaves appear green—and why the purple panels transmit these two wavelength bands. (Image: Wikimedia Commons, Serge Helfrich, CC BY-SA 4.0)
For the two panel types labeled 50% and 70% transparency by the manufacturer, the research team measured actual photosynthetically active radiation (PAR) transmittance of 13.2% and 19.2%, respectively. The panels’ semi-transparency is achieved not because the photovoltaic cells themselves are transparent, but through gaps between opaque CdTe cell strips combined with a color filter (PVB) layer that selectively passes light. Narrowing the gaps reduces transparency but increases power generation efficiency.
In the 2024 cultivation trial, broccoli beneath the solar panels took 104 days to reach harvest due to reduced sunlight, compared to 79 days in open fields. Final yields, however, were similar. The weight and size of harvested broccoli showed no significant difference from open-field cultivation.
Broccoli exhibited an adaptive response, producing more leaves as light levels decreased to maximize photosynthetic efficiency. Under panels labeled 50% transparency, leaf count increased 31% compared to open-field plants; under 70% panels, the increase was 25%. Light-use efficiency rose by up to 4.5 times and 2.8 times, respectively.
The semi-transparent panels also acted as a moisture barrier. During the day, water evaporation from the broccoli decreased, maintaining higher relative humidity. The research team explained that in hot, dry environments, the solar panels reduced crop water loss and climate stress.
Broccoli grown beneath the solar panels showed no significant nutritional differences from open-field cultivation. Macronutrients including calcium, magnesium, potassium, and nitrogen were comparable to or even higher than open-field levels. Calcium was 51–54% higher, magnesium 25–37% higher, and potassium 32–42% higher than open-field broccoli. By contrast, micronutrients such as copper, iron, zinc, and manganese, along with water-soluble carbohydrates, were somewhat lower than in open-field cultivation.
The table below summarizes key metrics for the two panel types and the open-field control group. PAR transmittance values are the research team’s actual measurements; the remainder reflect 2024 cultivation trial results.
The key metric highlighted by the research team is land-use efficiency. Combining solar power generation with crop cultivation enables the same output using 18% less land than dedicating land to either purpose alone. The calculation shows that 1 hectare of dual-use land produces output equivalent to 1.18 hectares of single-purpose land. This assumes installation of 500 systems per hectare (10,500 panels total, 546 kWp), combining 224.7 MWh of electricity generated during the growing period with broccoli dry-weight yield.
The photoelectric conversion efficiency of the CdTe thin-film panels was 7.2%—roughly one-third of silicon panels, which exceed 20%. However, because they can be installed at low tilt angles and densely arranged, actual power output reached 69.1% of a conventional bifacial silicon system (325.2 MWh) on the same site. Crop yield was 81.8% of open-field levels, and factoring in the 40% land loss from panel framework, overall productivity was calculated at 49.2% of conventional systems. Using fresh-weight figures—closer to market value—crop contribution rises to 93%.
The semi-transparent solar panels are expected to be applicable to crops beyond broccoli. Researchers at Colorado State University reported in 2024 that various crops—including turnips, basil, lettuce, bok choy, ginger, sweet potatoes, bell peppers, and tomatoes—maintained or even increased yields beneath semi-transparent solar panels.
Professor Campana noted that electricity generated by the panels could be used for irrigation or cold storage, reducing farmers’ electricity bills and creating an additional income stream. He cautioned, however, that the system tested remains at the prototype stage and requires larger-scale, long-term cultivation trials. The paper explicitly states that these results are exploratory, derived from a single growing season with a single test plot per treatment. The experiment took place in central Sweden at latitude 59.5°N—a high-latitude temperate region—and the authors acknowledged that in areas with lower solar radiation, harvest delays could be longer, while in regions with short growing seasons, broccoli might not reach marketable size. Conversely, in hotter, sunnier regions, the panels’ shading and wavelength filtering could prove even more beneficial to crops.
In Japan, “agrivoltaics”—installing panels above farmland while continuing to farm beneath—reached a cumulative 6,137 installations covering 1,361.6 hectares of panel-shaded farmland by the end of fiscal 2023. However, cases where farming beneath panels was disrupted reached 24%, prompting Japan’s Ministry of Agriculture, Forestry and Fisheries to implement a new system from April 2027 establishing “desirable agrivoltaics” standards: shading rates below 30% (or solar radiation reduction below 20%), minimum ground clearance of 3 meters, and support post spacing of at least 4 meters. In this experiment, broccoli beneath the panels received PAR equivalent to 13–19% of open-field levels—conditions far darker than Japan’s new standards, though the metrics are not perfectly comparable.
Taiwan has effectively prohibited solar facility conversion on farmland under 2 hectares since July 2020, and greenhouse rooftop solar is limited to 40% of roof area while requiring crop yields to remain at 70% or more of previous levels. As attempts to combine solar power with agriculture increase, the weight of data proving “farming can still work beneath panels” grows accordingly.
The installation of solar panels on farmland amid renewable energy expansion has long been contentious. With proponents citing utilization of idle land and opponents warning of threats to food security from farmland loss, this study is notable for demonstrating the technical feasibility of achieving both objectives simultaneously.
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