Solar Farms: Investigating the effects on soil quality in Wales

Abstract

The rapid expansion of utility scale solar photovoltaic (PV) energy across the UK has raised concerns about its ecological consequences, particularly regarding soil quality indicators (SQIs) that underpin ecosystem services and agricultural sustainability. This study investigates the effects of ground-mounted solar farms on physical, chemical, and biological SQIs across multiple sites in Wales.

Field sampling was conducted at four operational solar farms, comparing soils beneath solar panels with soils in the interspace between rows, in the boundary areas of arrays, and adjacent control fields. Data were statistically analysed to assess treatment effects and site-specific variability.

Both biological SQIs measured (soil respiration (SR) and root density) were consistently and significantly lower beneath panels compared to other areas of the solar-PV sites. This is strong evidence that soil biological activity and plant productivity are negatively affected beneath solar panels. The reduced rooting could hinder soil recovery from compaction caused during the construction phase of the solar farm. Chemical SQI results (including soil pH, electrical conductivity (EC), total soil carbon (C) and nitrogen (N), and extractable nutrients) were largely inconclusive, with high site-specific variability.

Several physical SQIs were found to be significantly impacted by panel presence. Soil temperature results were mixed, but reaffirmed findings from previous studies that panels cause diurnal and seasonal variations in soil temperature. Soil temperature was also linked to SR, indicating that temperature variation caused by panels had significant effects on soil biological activity. Soil moisture content was significantly lower beneath panels, confirming that rainfall interception reduces soil moisture content. Bulk density (BD) was significantly higher beneath panels than in gaps at agricultural sites. While increased BD in solar farms is likely caused in the construction phase, this study found critical thresholds of compaction were not exceeded.

Overall, we found that solar farms significantly affect several physical and biological SQIs when situated on agricultural land, and could therefore cause changes in associated ecosystem services such as productivity. Whether these effects persist after decommissioning remains unclear, but interventions during the planning, construction, and operation phases of solar farms could be implemented to mitigate these impacts.

Date of Award	27 Jan 2026
Original language	English
Sponsors	Kess II East
Supervisor	Davey Jones (Supervisor) & Dave Chadwick (Supervisor)