Soil Moisture and Temperature Around an Internal Gap in a Ground-Mounted Photovoltaic Structure: The Czech Republic Case Study

Ground-mounted photovoltaic structures create contrasting soil environments, but an internal opening within one support is not equivalent to an inter-row corridor. This observational case study monitored ten time-domain reflectometry probes at 20 cm in temperate grassland in Central Bohemia, Czech Republic, from May to October 2025. Two under-panel rows, an internal gap formed during module replacement and one open-position moisture probe, were compared using daily trajectories, twelve rainfall blocks and three rain-free blocks. Two soil-temperature profiles at 5–20 cm were evaluated from 7 June. The daily mean recorded water content in the gap exceeded the six-probe under-panel mean on all 184 days, whereas the open probe recorded lower water content than the under-panel mean on thirteen August days. During a 34.4 mm rainfall block, gap probes increased by 5.3–9.3 percentage points, while changes within one under-panel row ranged from 0.1 to 11.0 percentage points. At 5 cm, mean daily temperature amplitude was lower under panels in all eleven thermally assessable blocks, although mean temperature was higher in eight. These observations describe local moisture and temperature patterns within one structure. Unmeasured soil variability and the lack of site-specific TDR calibration limit attribution of the differences to the PV configuration. Water-flow pathways and causal effects of gap formation or repowering were not established.