What is a solar farm?

As our urgency for cleaner, renewable energy becomes ever more significant, solar farms are becoming an everyday sight across Britain. Rows of dark, shiny panels harvesting sunlight are also proving a popular choice for landowners looking for alternative income streams.

Visible from space, Xinjiang solar farm in China dwarfs all others around the world with a solar capacity of 5 gigawatts (GW). Spanning 81,000 ha of desert, this solar farm could power Luxembourg for an entire year. Here in the UK, Shotwick Solar Park in Flintshire is still our largest array at 72 megawatts (MW), providing power via a private wire connection to the UK’s biggest recycled paper mill.

Solar farms are large scale installations of photovoltaic panels converting energy from the sun that’s, typically, fed directly back to the National Grid. Ranging in size from a handful to hundreds of acres, they can either be ground mounted panels on rural or agricultural land (known as Solar Farms) or erected in urban areas such as apartment roofs (known as Solar Parks).

The drive to convert to renewable energy sources, including solar power, is part of the UK government’s net zero targets. Ministers are aiming for a “fully decarbonised, reliable and low-cost power system”, with a goal of achieving 70GW of solar power by 2035.

I want to build a solar farm…

For every 5MW of solar capacity generation you will need approximately 10ha of land on which to install solar panels. An installation of this size would then power around 1,500 homes for a year, based on average UK consumptions of electricity.

Just under half of the UK’s 1,170 solar farms that are operational or under construction are in the South East and South West of England and as of July 2024 cumulative installed capacity of solar power in UK was 16.9GW (Government figures).

EON Energy estimates that the average cost of building a large-scale solar installation is around £1 million per megawatt of capacity with a lifespan of about 25 years. With almost 30 million homes in the UK, this gives you an idea of what still needs to be built to achieve those government targets, and just how much it could cost.   

What are the planning rules around solar farms?

Solar farms require planning permission. Should you be looking to develop a farm with a generation capacity below 50MW then this permission is gained from the local planning authority. Thinking bigger? Then any solar farm over 50MW becomes a nationally significant infrastructure project (NSIP) and will need development consent from the Secretary of State. However, with a new Labour government in place, this regulation is now under consultation and could raise the threshold for NSIPs to 150MW. Either way, you will need an Environmental Impact Assessment (EIA) to go ahead with the development.

The process of gathering an EIA enables a deeper understanding of how the proposed solar farm could impact biodiversity and the wildlife currently living on or utilising the land. This baseline surveying gathers data on air and water quality, soil composition, and the abundance of birdlife, invertebrates, mammals and plant life. It then proposes mitigation measures which could minimise any negative impacts potentially caused by the solar farm or how to enhance any positive impacts.

The purpose of an EIA isn’t to dissuade an LPA from permitting a solar farm but can, in fact, showcase its potential for biodiversity gain. Labour’s consultation paper could also encourage more solar farm development as it seeks to “give significant weight to the benefits associated with renewable and low carbon energy generation”. As we all turn our focus to the creation of green energy sources, we just want to ensure that the actual physical work we are doing to achieve this also benefits our environment.

Solar farms and biodiversity

Construction of a solar farm necessitates space in between the rows of panels to allow access for maintenance work to be done. This creates an interesting habitat of exposed sunlit areas alongside shaded, cooler areas. The tilt of the panels also affects how rainwater falls onto the ground and collates.

The initial work needed to install a solar farm includes some ground, and therefore habitat, clearance as well as soil compaction and an alteration to drainage channels. This could be detrimental to wildlife in the short term. So how can these new habitats create an opportunity for biodiversity? It comes down to future management.

At a very basic level, permanent grassland – in contrast to intensively managed agricultural land – removes the need for fertilisers or pesticides. In turn, allowing the health of the soil to improve naturally.

In 2022, an experiment at Keele University installed 12,500 solar panels together with two wind turbines and a large storage battery connected to the university campus. Researchers found that the ground quickly recovered after installation, naturally establishing a native grassland habitat that was richer in biodiversity than the ploughed field which existed before.

How to improve the biodiversity within a solar farm

This is where the active management comes into play. Eden Renewables says, “A well-managed solar farm can become a nature reserve for its operational lifetime”. Solar Energy has recently published research that states, “solar farms can become havens for biodiversity, playing an important role in nature restoration across the country.” For many of the UK’s solar farms, the opportunity for biodiversity net gain lies between the panels where species-rich grassland can be managed as a hay meadow with aftermath grazing by sheep.

Not only this, large volumes of land provide an opportunity to plant native hedgerows and field margins surrounding the panels. As long as panels can be reached for maintenance, then even more biodiversity can be introduced with natural ponds being dug. Displaced construction soil can be left as bunds, where shrubbery and scrub will naturally establish. Leaving bunds in place can also strip the nutrients from the original arable land and enable species-rich grassland to be established more effectively. Hedgerows, scrub, water, and grasslands all provide habitat for invertebrates and, as a consequence, small mammals, amphibians, reptiles and both foraging and breeding birds will be attracted.

Solar panels can create small microclimates due to the shade they produce. Soil temperatures are cooler which can affect the biodiversity of plant life but also offers relief for grazing sheep during warmer months. A new practice of agrivoltaics is also taking root, with farmers installing panels at a height to enable crops to be grown beneath. With those in warmer climates reporting increased yields thanks to the shade which also prevents the evaporation of rain water. 

What’s important, however, and has recently been recognised by the Parliamentary Renewable and Sustainable Energy Group who are championing the potential nature positivity of solar farms, is that any biodiversity considerations are “incorporated from the planning stages”. Suggestions have also been made recently that more of a collaboration is needed between the solar industry and conservation organisations like The Wildlife Trusts and the RSPB to get things right from the word go.   

Ecological monitoring of solar farms

In the grand scheme of things, solar farms are relatively new to the UK and, until recently, no standardised monitoring existed to ascertain the relationship between the management of solar farms and the biodiversity of the land they cover. However, the recent introduction of mandatory biodiversity net gain came with an obligation to both monitor and manage that biodiversity for 30 years.

In 2022 Solar Energy UK and Lancaster University, together with a group of stakeholders, created and published a: “standardised approach to ecological monitoring on solar farms.”  This they hope will be adopted by solar farmers, local authorities and developers. Although only two years’ worth of data exists so far, the idea is to create comparable year on year robust data in order to monitor changes in the relationship between the land, the PV panels and the wildlife.

So far, their survey work has shown positive results, with a diverse range of plant, invertebrate, bird, and mammal species noted across 87 solar farms. This included 21 Red Listed bird species including the iconic skylark which has been disappearing from our British farmland at an alarming rate. Again, those farms which showed the greatest abundance of wildlife were also recognised as managing the land proactively for biodiversity. Actions such as conservation mowing or grazing, removal of arisings, and the creation of a range of habitats had the biggest impact.

At Ecology by Design we feel that, with solar panels having an average lifespan of 25 to 30 years, their installation goes hand in hand with the new BNG monitoring and management commitments. The creation of solar farms is yet another opportunity to thoughtfully consider how our land is used in the most environmentally friendly way possible whilst also recognising the challenges that climate change is bringing.

Our expertise in understanding this, together with the workings of the BNG metric, presents a wealth of opportunity for us to work with solar farm planners and developers to achieve a solution for our environment and wildlife in the long term.

August 2024