Page 372 - A Comprehensive Guide to Solar Energy Systems

Chapter 19 • Solar Panels in the Landscape 379

many hectares. The main disadvantage is the removal of the land from otherwise poten-
tially more productive agriculture.
Free-standing solar farms can vary in size from a few panels or a few hectares, to vast
areas of panels, such as the recently constructed Tengger desert Solar Park in India which is
2
spread over 43 km and generates 1500 mW. most uK solar farms are in the order of 8–12 ha
(20–30 acres). The largest solar farm in the uK is currently Shotwick Solar Farm, Wales, which
covers 90 ha and generates 72 mW, but now there are proposals for schemes of over 100 ha.
Large solar farms made up of arrays of panels may stretch for considerable distances.
In the uK, arrays of panels are typically designed to fit within the existing field pattern,
to preserve the landscape pattern of hedgerows or walls [6]. This is done for reasons of
preserving landscape character, long-established field boundaries that can be important
ecological resources in the landscape, and for purposes of screening from nearby loca-
tions. As arrays are usually in south-facing rows, this can lead to a diagonal orientation
with respect to rectilinear field boundaries. Space must be left around the edges of the
fields to avoid shadow by hedgerows or trees and to allow turning access for maintenance
vehicles. As a result, large solar farms in the uK are typically made up of several fields of
arrays rather than long uninterrupted lines that are possible with extensive unenclosed
land in other parts of the world.
Panel arrays are arranged in rows to avoid shadowing and allow maintenance access,
and are elevated off the ground by 1–2.5 m. As a result, there is light that will reach the
ground between the arrays, and although the panels shade the ground below them, there
is sufficient light for vegetation to grow. This vegetation ground layer can be maintained
as a wildlife resource or can be grazed by sheep, which have the benefit of a secondary
agricultural use for the land. Cattle are not suitable for grazing among solar panels, as the
larger animals could damage the panels or infrastructure and would need greater clear-
ance off the ground.
The mounting frames hold the panels at an inclined angle that can be calculated for
optimum solar yield for a given latitude [7]. Panels are usually set at a fixed orientation
and tilt, though some developments are mounted on frames that allow for adjustments in
tilt and orientation, for tracking the sun to gain maximum yield. These solar tracker arrays
have higher maintenance costs, require greater land take to avoid shadowing each other,
and are generally not seen in new installations.
mounting frame ground anchors can be piled or poured concrete foundations, though
the former is favored for speed of construction and ease of decommissioning and may
form part of conditions for consent (Fig. 19.7). In areas of archaeological interest, pre-
molded concrete blocks or “shoes” may be required as they minimize ground disturbance
and are easy to remove [8].
In the uK, solar farms are considered to be temporary structures and planning condi-
tions can be used to ensure that the installations are removed when no longer in use and
the land restored to its previous use. however, in the lifespan of the installation (usually
around 20 years), it is likely that technologies will advance and “repowering” of old sites
may be an alternative to full decommissioning.