What are the ecological impacts of solar farms?

Guest blog by Ken Neal, Ecologist

In order to meet its targets for de-carbonising energy production in the UK, recent governments have resorted to consenting large-scale solar PV installations on farmland in our countryside. Farmers are also more frequently resorting to these installations as a way of making ends meet as their costs for fuel, fertiliser and pesticide increase whilst return from their produce decreases. These solar ‘farms’ are often controversial especially for their visual impact and I have seen them referred to as “monstrous” on social media along other less savoury descriptors. I have also seen many references on social media to “damage to wildlife” that these installations supposedly cause, but are they really that bad?

Modern farming is a long way from the bucolic scenes of the pre-1940’s which involved few livestock and men working the land cutting winter forage and cereal crops mainly by hand. Farming in the UK today is nothing short of industrial in its scale, requiring huge amounts of fossil fuel to drive machinery as well as massive inputs of artificial fertilisers and pesticides to maintain the sort of yields required to feed a growing UK population as well as remain (marginally) profitable for those that work the land. This also means that arable land is usually cropped twice a year with fields cultivated in spring and late summer with cultivation right up to the margins of the fields with their tightly cut hedges. Long gone are the scruffy edges of fields, on most modern farms every last scrap of space is used to produce crop or grass to feed livestock.

Silage fields are at most two plant species and are cut so often that ground-nesting birds and bees stand little chance. Makes putting up some arrays of solar
panels seem relatively benign doesn’t it? But installation of solar PV isn’t just a relaxation of intensive use of the land – each of the projects is subject to planning law meaning that a whole host of surveys need to be undertaken before an application for consent to build can be submitted to the relevant authority. These surveys include socio-economic impacts, heritage, flooding and land management as well as appropriate ecological surveys which typically involve botanical survey, bat surveys, bird surveys and in the relevant areas surveys for badger, otter, dormouse, reptiles, amphibians (especially great-crested newt) and rare invertebrates. All of this information is fed into an Ecological Impact Assessment or EcIA which will determine what impacts (positive or negative) the solar development is expected to have. The EcIA is submitted with the planning application and in many cases will lead to certain conditions, imposed by the planning authority, to safeguard biodiversity on a given plot.

But what impacts can be expected from installing solar? There are potentially many effects including during construction from machinery being on land, the potential need to remove vegetation to avoid shading of the panels and breaking ground to install cables and substations. However three immediately come to mind:

1. Shading – solar panels are partially translucent meaning that some light does pass through but only enough that shade-loving plants will flourish beneath, to the exclusion of open-habitat plants meaning that there may be a change in flora under the panels. Don’t expect any solar farms to get approval on chalk grassland any time
soon.

2. Ground-nesting birds – including species such as curlew, lapwing and skylark all of which are in serious decline in the UK. These species need open areas of short
vegetation in which to nest so that the adults can see approaching predators early. They do not like solar panel arrays.

3. Bats – a recent study showed a decrease in bat activity over solar arrays compared to similar open areas in neighbouring fields whilst activity along field margins didn’t
really change. It has been hypothesized, but not proven in any way, that this is because the bats perceive the solar arrays as open water which they will not forage over.

So what can be done (and is done) under planning conditions to mitigate for these sort of impacts? Well for one, solar farms are usually put on farmland that has been intensively exploited and so impacts to flora are rarely an issue. As an example we can take a look at a solar farm that I worked on in South Wales that was actually installed on a SSSI (Site of Special Scientific Interest). The site designation was for some local waterbodies not the actual land so one of the planning conditions was a
programme of works to improve the waterbodies for the rare plants and invertebrates that they supported. The land on which the solar panels were installed was previously intensively grazed by sheep so this was changed to much lighter grazing to maintain a grassy sward but with much more floral diversity. Hedgerow management was changed so that they were cut much less often and bat boxes were installed in standard trees. In addition, to satisfy a number of conditions, the energy company leased more fields than they needed for the solar arrays, three of which were harrowed and seeded to create new wildflower meadows to support rare invertebrates (and by default foraging bats and insectivorous birds). A further two fields also had the grazing regime altered to benefit nesting lapwing.

Monitoring of the site (another planning condition and paid for by the energy company) showed some success early on: the meadows were taking shape and counts of invertebrates were increasing within them and a bat was found using one of the boxes. The project is in its early stages and close co-operation with the energy company meant that any deviations (such as the farmer putting too many sheep on the land in the summer) could be quickly corrected and overall efforts to improve biodiversity as a result of the planning conditions appeared to be going in the right direction.

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