Agriculture is often the target of criticism related to high energy consumption. New ways of growing food, including placing solar cells directly above plants, could also bring this area closer to carbon neutrality.
solar cells above plants is also called agrivoltaics, and it can be used
to boost both yields and the efficiency of the solar cells. When
planting a crop under a solar collector array, the plants grow better and
need less watering, and the solar panels produce large amounts of
electricity without interruption.
plants need sunlight, but too much sunlight can do more harm than good, as some
plants get stressed when the sun is too intense. Furthermore, plants will
require less water, which rapidly evaporates in an open field.
cool themselves in the process of “sweating”, more professionally
called transpiration, in which water evaporates from leaves, stems,
flowers and fruits. This process cools the panels above as well and
consequently increases their efficiency.
A few years ago, a study was published in Nature Sustainability, in which experts examined all aspects of sunlight, air temperature and relative humidity. They concluded that croplands are currently the land “with greatest solar PV power potential“. Grasslands and wetlands also ranked in the top three land covers.
have successfully grown aloe vera, tomatoes, biogas maise,
pasture grass, and lettuce in agrivoltaic experiments. The
research abstract said that some varieties of lettuce produced greater yields
in the shade than under full sunlight; other varieties produced essentially the
same yield under an open sky versus under PV panels.
“Many of us want more renewable energy, but where do you put all those panels? As solar installations grow, they tend to be out on the edges of cities, and this is historically where we have already been growing our food,” saidGreg Barron-Gafford, associate professor in the School of Geography and Development at the University of Arizona and lead author on the paper.
land use do you prefer — food or energy production? This challenge strikes
right at the intersection of human-environment connections, and that is where
geographers shine!” he explained. “We started to ask, ‘Why not do produce both
in the same place?’ And we have been growing crops like tomatoes, peppers,
chard, kale, and herbs in the shade of solar panels ever since.”
A few months ago, Bloomberg wrote about Takeshi Magami’s farm in Japan, where the 2,826 solar panels are perched above the crops.
covering much of the one hectare of land east of Tokyo, serve a dual purpose.
They supply nearly all the power needed to run the farm and are a source
of extra income by selling surplus renewable energy to the grid.
owner, this means 24 million Japanese yen or 174,000 EUR of additional
income per year, eight times more than the approximately 3 million yen
generated from the crops. Magami benefits from tariffs that have been reduced,
but this is nevertheless an indication of the value-added creation available to
farms in Japan and around the world.
They are also interested in similar projects in Kenya, an African country, where they decided to place solar cells above crops in February, according to the Guardian.
Previously, experts from the University of Sheffield, World Agroforestry and the Kajiado-based Latia Agripreneurship Institute conducted year-long research in the semi-arid Kajiado county.
Cabbages grown under 180 345-watt solar
panels have been a third bigger and healthier than those grown in
control plots with the same amount of fertiliser and water. Other crops, such
as aubergine and lettuce, have shown similar results. Maise grown
under the panels was taller and healthier, according to Judy Wairimu,
an agronomist at the Institute.
panels can be placed three metres from the ground, providing ample room
for a farmer to work below or higher in bigger systems to allow access to
technology has been employed in other countries, including France, the US and
Fabian Karthaus in Germany grows berries under solar power systems. “I can’t feed a family with the earnings from growing 80 hectares of field beans, grain, rapeseed, and corn crops,” he explained to DW. “That’s how the idea of growing berries under a solar roof with translucent modules was born. We thought about which kind of berry goes with what sort of light and shade. Blueberries and raspberries are woodland plants, so that works really well,” he added.
suspects the shade under the modules could increase yields. Sweltering
summers are now an increasing problem for plants, even in Germany. And as
already mentioned, roofs made of solar modules reduce evaporation. “The
evaporation is about a quarter compared to plants in the open field,” he
kilowatts of power, the system generates about 640,000 kilowatt hours
(kWh) a year, equivalent to the electricity needs of 160 households.
Karthaus receives a little less than 0.06 EUR per kWh for feeding it
into the grid. He also plans to use part of the solar power to operate his
refrigeration and lyophilisation (freeze-drying) systems. If he had to buy the
electricity from the energy supplier, that would cost him around 0.25 EUR
Author: Marko Želko
Keywords: solar energy, environment, agriculture, food.
article is part of joint project of the Wilfried Martens Centre for European
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