# GIS-Based Solar Radiation Mapping, Site Evaluation, and Potential Assessment: A Review
## 4 Solar Potential Assessment Using GISs
### Spatial Analysis Tool  
Spatial analysis in a GIS environment is a concept in contrast to general analysis, which does not take into account spatial characteristics. Spatial analysis includes any of the formal techniques used to investigate entities based on their topological, geometric, or geographic properties. These techniques include various approaches such as rooftop extraction and solar radiation modeling. However, the roles of GISs for spatial analysis discussed in this sub-section are confined to simple geospatial analysis tools such as map algebra, overlaying, reclassification, slope, orientation, distance, and so on. In some studies, map algebra analysis (including filtering) or overlaying of two or more maps was employed to generate new maps. [PERSON] and [PERSON] [81] identified the potential of using CSP to generate electricity in a rural region of Western Australia. Potential CSP sites were defined by overlaying environmental variables and electricity infrastructure on a high-resolution grid using widely available datasets and ArcGIS. The CSP potential map regions were classified as high potential, medium potential, and low potential, and the statistics of each class were calculated. [PERSON] et al. [82] generated transmissivity and diffuse proportion maps by applying map algebra analysis to maps showing the proportions of clear days, partly cloudy days, and cloudy days in Hong Kong. Moreover, the slope of the terrain was analyzed and rooftops with angles of more than 40\({}^{\circ}\), which is regarded as maximum for installing PV modules, were excluded. Subsequently, building footprint and solar potential maps were spatially joined, within a GIS environment, to calculate the rooftop PV potential in Hong Kong, [PERSON] et al. [83] overlapped solar radiation in the areas exploitable for solar energy production. Subsequently, the electricity consumption and potential production were investigated for each district in Central Italy. [PERSON] et al. [84] generated a map showing the spatial distributions of geographical constraint areas such as built-up, non-built-up, and unsuitable areas. Then, technical potential and unit generation cost maps for each area were created by using a few equations. Furthermore, the simple payback period value, net present value, and carbon reduction potential for each area were calculated and visualized via map algebra analysis based on several equations. [PERSON] et al. [85] generated two TRNSYS-based solar power output maps, one in which temperature was ignored and one in which it was considered, to examine the effects of temperature on PV systems. The power output differences for 236 cities across the US were used to generate contour maps indicating a continuous surface of differences between these two approaches via map algebra analysis. [PERSON] et al. [86] included wasteland areas for solar potential calculation using a filtering approach in a GIS environment. Conversely, areas with average slopes greater than 2.1% and those with less than minimum thresholds of 4.0 kWh/m\({}^{2}\)/day for GHI and 5.47 kWh/m\({}^{2}\)/day for DNI, were excluded to calculate the solar potential for suitable areas. [PERSON] et al. [87] proposed GIS-based approaches to analyze various renewable energy technical potentials in the US. Various spatial analysis tools were utilized to estimate the system performance and for mapping, including various solar PV and CSP systems. Several researchers applied spatial joining of two maps (of different types) or spatial comparison of maps. [PERSON] et al. [88] spatially compared solar and wind potential maps to calculate hourly, daily, and monthly wind and solar electricity correlation coefficients in Italy for 2005. Based on the results, the complementarity of wind and solar resources for energy production in Italy was assessed using a Monte Carlo approach. [PERSON] and [PERSON] [89] assessed five different renewable energy potentials on US marginal and contaminated sites that could be re-used.