# GIS-Based Solar Radiation Mapping, Site Evaluation, and Potential Assessment: A Review
## 1 Introduction  
With growing concerns about greenhouse gas emissions, the security of conventional energy supplies, and the environmental safety of conventional energy production techniques, renewable energy systems are becoming increasingly important and are receiving a great deal of political attention [1]. In particular, photovoltaic (PV) and concentrated solar power (CSP) systems for the conversion of solar energy into electricity have been found to be technologically robust, scalable, and geographically dispersed and possess enormous potential as sustainable energy sources [2] (The full terms and their abbreviations referred to in the paper are summarized on the last page of this paper). Despite the advances in PV and CSP technology, inappropriate planning and design could impede the extensive penetration of solar energy. Systematic planning and design considering various factors and constraints are necessary to deploy PV and CSP systems successfully.  
To achieve these objectives, geographic information system (GIS)-based methods have been applied effectively for rational solar power system planning and design. GISs have often been combined with analytical models and methods (e.g., probability/statistical, machine learning, and data mining methods) to complement the inherent capabilities of GISs in evaluating the spatial patterns or characteristics of events and their attributes.  
The objective of this study was to review the GIS-based methods and applications currently used for solar radiation mapping, site evaluation, and potential assessment associated with PV and CSP systems. The scope of this review was confined to published literature related to GIS-based methods and applications in solar radiation mapping, site evaluation, and potential assessment of PV and CSPsystems. There are numerous recent review papers dealing with solar potential [3; 4]. The distinct difference between the aforementioned studies and this paper is the scope of GIS applications. In this study, we tried to investigate and summarize overall roles and applications of GIS to research associated with solar energy (not only focused to solar potential). Keywords (i.e., GIS, solar or PV or CSP, modeling or radiation or mapping or evaluation, or assessment) were inputted into the Google Scholar website to search the published literature, and 92 articles were selected for review. Specifically, three different keywords (A, B, and C) were combined and inputted to search papers (e.g., GIS, PV, and modeling). Then, 92 articles were selected for review by analyzing the title of the searched papers by authors. Even so, it should be noted that the number of papers included in this topic is not necessarily 92. Articles concerning remote sensing technologies for solar radiation mapping were excluded from this study if they did not involve any GIS-based methods.  
This paper is organized into five sections. Section 1 introduced the main concept. Section 2 reviews the literature dealing with solar radiation mapping using GISs. Sections 3 and 4 describe the GIS-based methods and applications for solar site evaluation (geospatial suitability) and solar potential assessment (electricity production), respectively. Finally, the conclusions are summarized in Section 5.