Interference effect of solar photovoltaic array on near surface aeolian sand transport in sandy areas

Deserts are ideal places to develop ground-mounted large-scale solar photovoltaic (PV) power stations. However, it is evitable surface erosion that may occur after the construction of a solar PV power station, where solar energy production, operation, and maintenance depend mainly on geomorphological changes in sandy areas. This study aims to investigate the characteristics of wind-sand movement under the interference of solar PV array, thereby reducing the damage to solar energy. The study area was located in the middle part of the Hobq Desert in China. The observation field was 300 m from the west edge of the test solar PV power station that was built at the end of 2018. There were no any protective measures on the surface of the solar PV power station during the test, such as sand-binding plants or sand-barriers. Field observations were conducted from 20 March to 13 April 2019. The reason was that the aeolian sand activity was the strongest in the study area during from March to May, due to the frequent occurrence of strong wind, extended drought, and limited rain. Thus, wind erosion led to the formation of trenches in the immediate vicinity of the downwind of panels, and sand ripples between adjacent north-south panels. The surface surrounding the test PV panels was smoothened, while the underlying surface was flattened before the experimental instruments were arranged. The flatting operation allowed for the comparison of experimental data. Sediment transport was measured in different wind directions above shifting dunes at three observation sites around the PV panels, such as between, in front of, and behind the panels. Meanwhile, the wind speed and direction were recorded using a HOBO sensor at the observation sites of shifting dunes. The sediment transport data was also collected at sixteen wind regimes. Sand-fixation of solar photovoltaic array, aeolian-sand flow structure and fitted model around the PV panels were then analyzed under the different wind regimes. The results showed that the near-surface sand transport rate above shifting dunes was always larger than that in the solar PV array in all cases, where the intersection angle between the solar PV array and wind direction was a key parameter to dominate the sand inhibition rate of solar PV array. Specifically, the sand inhibition rate ranged from 35.34% to 93.02% at the angle range from -12.30° to 82.19°. The mean value of sand transport rate above the solar PV array reduced to 84.63%, compared with the shifting dunes, especially with the angle exceeding 45°. There was also no change in the sand transport rate model when applying the solar PV array, similar to the shifting dunes. A two-parameter exponential function was better fit for the measured profiles of flux density on the near-surface of solar PV array. Wind-sand flow between and behind the panels tended to evidently move towards a high layer with the angle increased, where the rising range was 8-10 cm, whereas, the saltation height at the observation site before the panels tended to move towards a low layer, where the decrease range was 4-5 cm. The finding can contribute to the understanding of the wind-sand movement characteristics under the interference of solar PV array, providing insightful ideas to plan better technical schemes against wind-sand hazards at solar PV power stations.