Page 50 - Energize March 2022

TECHNICAL

Agrivoltaics: A win–win system

for agriculture

Harvesting the sun’s power has become one of the main tools in the shift to a sustainable energy
future, and private solar generation plant is on the increase, particularly in the agriculture sector.

BY MIKE RYCROFT, ENERGIZE

his comes with a potential risk: solar farms require large underneath and around the array can be varied to suit the
amounts of land. Many farms in South Africa are installing requirements of the crop. The principle is being applied to open
TPV, with the threat of loss of arable land particularly in field, covered field and greenhouse crops. AGV has been found to
market crop areas. Agrivoltaics provides a means to use land for increase crop yields, reduce water requirements, and increase PV
both power generation and agriculture. electricity production. 1
The first choice for any private solar generation system is The concept is known in Japan as “solar sharing” because
to use existing structures, such as rooftops, but large power plants only need a certain amount of sun energy per day,
generation requirements extend beyond the capability of and the extra is used for power generation. AGV is applied
rooftop structures, and not all rooftops are suitable for solar extensively in Japan, with over 2000 installations totalling
PV mounting. The only alternative is ground mounting. The about 200 MW in 2021.
main disadvantage of ground-based solar is that it uses
land space, which could otherwise have been used for crop Agrivoltaics has been successfully used in both concentrated
production or grazing. growth areas such as vegetable beds and in general coverage such
In most large-scale solar farms, the panels are mounted as grazing. The following areas are examples of usage:
as close as possible to the ground, and the area under and • Cereal crops such as rice
surrounding the panels is kept free of vegetation, to avoid • Vegetables and market gardening
shading and contamination from plant growth and insects. • Viticulture
The emerging field of agrivoltaics, (AGV) which is the • Forage and grazing crops
controlled use of ground-mounted solar on agricultural ground, • Specialist crops such as berries
allows use of the ground beneath and around the PV array • Fruit and orchards
to produce crops, giving a dual benefit of electricity and crop • Beekeeping and honey production
production. AGV is based on structuring the PV mounting array
in such a way that the amount of light and shade on the ground A study found that Southern Africa is one of the most suitable
regions for AGV. 1

Effects of solar PV shading on crops
Too much sunshine can negatively affect the growth of
plants. Plants can use only a certain amount of sunshine
per day. Any sunshine received after that “point of light
saturation” doesn’t help the plant grow or increase
photosynthesis. Instead, it increases the plant’s transpiration
and need for water, which means increased irrigation needs.
Certain crops benefit from regulating the amount of sunlight
that they receive, and many crops show adverse growth
under conditions of too much sunlight.
With agrivoltaics, the panels can be positioned to give the
plants the right amount of sunlight and shade. An additional
advantage is that AGV application lowers the ambient
temperature under the panels resulting in up to 10% more
electricity production than in conventional ground mount use,
Figure 1: “Solar sharing” in Japan (Chiba ecological energy) according to field trials. 1

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