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Green Energy And Better Crops: Tinted Solar Panels Could Boost Farm Incomes

Green Energy And Better Crops: Tinted Solar Panels Could Boost Farm Incomes

Researchers have demonstrated the use of tinted, semi-transparent solar panels to generate electricity and produce nutritionally-superior crops simultaneously, bringing the prospect of higher incomes for farmers and maximising use of agricultural land.

By allowing farmers to diversify their portfolio, this novel system could offer financial protection from fluctuations in market prices or changes in demand, and mitigate risks associated with an unreliable climate. On a larger scale it could vastly increase capacity for solar-powered electricity generation without compromising agricultural production.

This is not the first time that crops and electricity have been produced simultaneously using semi-transparent solar panels - a technique called 'agrivoltaics'. But in a novel adaptation, the researchers used orange-tinted panels to make best use of the wavelengths - or colours - of light that could pass through them.

The tinted solar panels absorb blue and green wavelengths to generate electricity. Orange and red wavelengths pass through, allowing plants underneath to grow. While the crop receives less than half the total amount of light it would get if grown in a standard agricultural system, the colours passing through the panels are the ones most suitable for its growth.

"For high value crops like basil, the value of the electricity generated just compensates for the loss in biomass production caused by the tinted solar panels. But when the value of the crop was lower, like spinach, there was a significant financial advantage to this novel agrivoltaic technique," said Dr Paolo Bombelli, a researcher in the University of Cambridge's Department of Biochemistry, who led the study.

The combined value of the spinach and electricity produced using the tinted agrivoltaic system was 35% higher than growing spinach alone under normal growing conditions. By contrast, the gross financial gain for basil grown in this way was only 2.5%. The calculations used current market prices: basil sells for around five times more than spinach. The value of the electricity produced was calculated by assuming it would be sold to the Italian national grid, where the study was conducted.

"Our calculations are a fairly conservative estimate of the overall financial value of this system. In reality if a farmer were buying electricity from the national grid to run their premises then the benefit would be much greater," said Professor Christopher Howe in the University of Cambridge's Department of Biochemistry, who was also involved in the research.

The study found the saleable yield of basil grown under the tinted solar panels reduced by 15%, and spinach reduced by around 26%, compared to under normal growing conditions. However, the spinach roots grew far less than their stems and leaves: with less light available, the plants were putting their energy into growing their 'biological solar panels' to capture the light.

Laboratory analysis of the spinach and basil leaves grown under the panels revealed both had a higher concentration of protein. The researchers think the plants could be producing extra protein to boost their ability to photosynthesise under reduced light conditions. In an additional adaptation to the reduced light, longer stems produced by spinach could make harvesting easier by lifting the leaves further from the soil.

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