This study was carried out to demonstrate that geospatial techniques are highly efficient and effective for estimating the potential of rooftops for the deployment of solar photovoltaic systems in generating electricity in Calabar Municipal.

To achieve this, four (4) factors were examined within the GIS framework as detailed below;

a.     Solar Radiation: The Solar radiation was extracted from the Digital Surface Model (DSM) of the study area using the area solar radiation tool of the spatial analyst tool in ArcGIS. By default, the solar radiation raster was produced in watt hour per m2 and was converted to the unit of kilowatt hour per m2 for ease and meaningful reading using a raster calculator under map algebra.

b.     Total Roof Area (Building footprints): The rooftops in the study area were extracted from a high-resolution satellite image through on-screen manual digitization to form a layer. The total area covered by the rooftops was calculated through the attribute table of the layer using the calculate geometry function of ArcGIS. The area was calculated in square meters, which was then copied into a Microsoft Excel sheet to find the summation. The summation will give the estimation of the total surface (roof) area available for the installation of PV panels.

c.     Slope: The Digital Elevation Model (DEM) of the study area from the Shuttle Radar Topography Mission (SRTM), which was acquired from the United States Geological Survey (USGS), was imported into ArcGIS 10.8 to produce the slope map of the study area using the spatial analyst tool’s function. The slope map produced in degrees makes it easier to expunge areas that have higher slope (>10°) based on the study criteria evaluation.

d.     Aspect/ Building Orientation: The Aspect map was produced from the DEM of the study area in ArcGIS 10.8. Using the analyst tool’s function. Under surface analysis, the aspect map was produced. It gave a value range and cardinal direction. This helps to know the direction each building in the study area is facing.

To determine rooftops in the study area that are suitable for solar PV installation, the solar radiation and available rooftops of the study area were subjected to a series of conditions as outlined by the various criteria that influence the suitability of rooftops for solar PV installation. Since slope, amount of solar radiation, aspect, and total roof area affect the suitability of rooftops for PV solar energy utilization, buildings that fall below the accepted range of these criteria were excluded from the analysis to get the total rooftops that are suitable for solar PV installation.

This map is the final suitability map (Suitable rooftops and associated solar radiation) in Calabar Municipal, Cross River State, Nigeria.