A study by North Carolina State University in the US found 'no real reduction' in plant growth or health of lettuce grown in greenhouses powered by see-through solar panels deployed atop to generate electricity. "It means the idea of integrating transparent solar cells into greenhouses can be done," said Heike Sederoff, Co-Corresponding author of the study and a Professor of Plant Biology at the university.
They created semi-transparent organic solar cells (ST-OSC) for their research work that they believe enable simultaneous plant cultivation and electricity generation thereby reducing the energy demand of a greenhouse.
For their experiment, researchers grew crops of red leaf lettuce in greenhouse chambers for 30 days, from seed to full maturity, with all other factors as constant, except for light, for the lettuces were divided into 4 experimental groups. One was exposed to the full spectrum of white light, and the remaining 3 groups were exposed to light through different types of filters that absorbed wavelengths of light equivalent to what different types of semi-transparent solar cells would absorb.
The color composition of light was also different for each of the experimental groups, even though the total amount of light incident on the filters was the same.
"Not only did we find no meaningful difference between the control group and the experimental groups, we also didn't find any significant difference between the different filters," added Brendan O'Connor, Co-Corresponding Author of the study and an Associate Professor of Mechanical and Aerospace Engineering at NC State.
What this means is that solar-powered greenhouses are a promising future reality, as there is increasing interest among growers, the team claims. "Getting growers to use this technology would be a tough argument if there was a loss of productivity. But now it is a simple economic argument about whether the investment in new greenhouse technology would be offset by energy production and savings," explained Harald Ade, Co-Corresponding Author of the study and the Goodnight Innovation Distinguished Professor of Physics at NC State.
For the future, the team believes OSC provide an opportunity for further light and thermal management of the greenhouse through device design and optical coatings. "The OSCs can thus impact plant growth, power generation, and thermal load of the greenhouse, and this design trade-space is reviewed and exemplified," reads the research.
The paper Balancing Crop Production and Energy Harvesting in Organic Solar Powered Greenhouses was published in Cell Reports Physical Science journal.
This study to understand how semi-transparent solar panels can affect greenhouse crops, is an extension of a previous study conducted by the university in February 2020 on how much energy solar-powered greenhouses could produce.