Page 52 - Energize March 2022

TECHNICAL

much wider choice of sun/shade ratios. Energy produced per row
is less than unspaced panel rows.

Standard panel rows with single axis tracking. (Figure 5)
This can consist of rows with or without spacing between panels.
The whole row tracks the elevation of the sun. This increases the
energy output of the PV. Tracking can be adjusted to suit crop
requirements.

Standard panels with dual axis tracking
Dual axis tracking systems have been developed for AGV. Fig. 6
shows two examples. In the first, pairs of panels are attached
to a central support which tracks east to west, and each pair
of panels is tracked north to south. The second example uses
groups of panels on a single tracking mount.

Specially designed crystalline panels
The problem with the use of standard panels is that the light is
not diffuse and homogeneous. To solve this, special panels have
been designed that meet the needs of the crops and electricity
generation. Panels specially designed for AGV use standard
crystalline wafers in a double glass construction, with spacing
between cells. Front and back encapsulants are transparent to
allow a specific amount of sunlight to filter through the spaces.
In some products glass is used which produces a diffused
lighting. This reduces the energy output of the panel but in
some systems this is compensated for by the use of bifacial
modules. The panels can be used in open field and greenhouse
Figure 4: Standard panel rows with spacing between panels. (NREL) configurations. One version is currently under test in a 2 MW
installation in Holland. 5

Lensed designs
These panels make use of a lens structure of the front glass to
divert sun to either crops or PV usage. The main use is green
house or covered field agriculture.
One design makes use of Fresnel lenses to direct sunlight to
either strips of crystalline PV material or to the interior, and this
depends on the sun’s elevation, which changes seasonally. The
design increases sunlight to the interior in winter and reduces it
in summer.
Figure 5: Row tracking panel structure (Axial Structural)

Figure 6: Dual axis tracking system (Agrovoltaico)

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