Professional Geophysical Survey for Site Selection of a Solar Energy Farm in Katsina State, North West Nigeria

Nigeria's ambition to expand renewable energy capacity includes the development of utility-scale solar photovoltaic farms, and North West states such as Katsina, with high solar irradiance and large areas of low-population-density land, are prioritised for solar farm development. Professional geophysical site investigation is necessary to assess the structural suitability of proposed sites for large-scale foundation infrastructure required for solar panel mounting systems. This professional study conducts a geophysical site suitability assessment for a proposed 100-megawatt solar farm site in Funtua Local Government Area using electrical resistivity tomography, seismic refraction, and microgravity survey. Six ERT profiles of 400 metres with Wenner array and six seismic refraction traverses were acquired in a grid pattern across the proposed 150-hectare site. A microgravity survey at 50-metre station spacing was conducted to detect any subsurface cavities or anomalous density contrasts. ERT models reveal a relatively uniform lateritic overburden of 3 to 7 metres depth overlying weathered basement. Seismic refraction results confirm that competent bedrock suitable for ground-anchor foundations is accessible at depths not exceeding 8 metres across 87 percent of the site. Microgravity data show no significant cavity anomalies, confirming the site is free from collapse hazard. Three small areas of the site with overburden exceeding 8 metres or with low seismic velocity indicative of loose material are mapped and recommended for modified foundation design. The study concludes that the site is geophysically suitable for the proposed solar installation with minor design modifications. Keywords: solar farm, geophysical site investigation, Katsina State, foundation, seismic refraction