Maps and solar radiation potential assessments (E)


Main author: M. Silva.

This chapter is focused on the products related with solar radiation maps and other products where geographical information systems are applied.
Geographic Information System (GIS) are tools for the compilation, consultation, exploitation and/or analysis of maps and geospatial data. Geospatial data are organized as a set of vector or raster layers, and the GIS software usually permits the visualization of multiple layers of information and provides specific methods and models that operate with those layers. In the field of renewable energy, GIS provide convenient digital environments that help developers to identify sites with high potential and permit policymakers to perform analyses oriented to the elaboration of energy policies (Broesamle et al., 2001).


TABLE 1. LOOK UP TABLE OF CATEGORIE AND USESGrey cells in Table 1 are later described. Cells width N.A. legend, means that no relevant applications are showed later.
Proyect developers needs at diferent plant stages Other users
Category of product service (A)
Feasibility & Design
Due Diligence Financing
Plant Accep-tance Test
Systems or Plant Operations
Grid operators
Policy makers
Education / Outreach
GIS & maps SEE >> N.A. N.A. N.A. SEE >> SEE >> SEE >> SEE >>

Solar radiation gridded information can be adequately represented by means of solar resource maps and GIS solar radiation layers. In addition to the representation, GIS tools helps too in the data access through standard protocols.

The main products included in this category are:

Solar radiation maps.

Solar radiation maps usually represent the spatial distribution of annual or monthly average values of solar radiation for a certain geographical region. In solar radiation maps (Diabaté et al., 1989), solar radiation values are usually represented by color codes. Solar resource maps in electronic format can be interactive, having the potential to display additional or extended information when a point or region of the map is selected.

Potential assesment of solar energy.

Potential assessment of solar energy are products much more elaborated than a solar radiation map (Broesamle et al., 2001). This type of product needs to fix several input parameters as: type of solar energy technology, specific characteristics of a power plant, land uses suitable with the selected power plant, and even local or regional subsidies. Figure 3 shows an example of a two steps solar thermal electricity (STE) potential assessment. In the first step, suitable zones are identified; and in the second one the electric power is calculated from an annual map of solar energy (Navarro et al., 2015).

Figure 3. GIS analysis for a two steps STE potential assessment. Unsuitable zones in black. (Navarro et al., 2015)

The relevant features for the application of GIS tools in the field of solar energy are:

  1. Spatial resolution. It is related with the grid size of the map. Depends mainly on the data source for the map generation.
  2. Region covered. It depends as well on the data source for the map generation. Even when the map covers the global Earth surface, the solar radiation estimation comes always from several data sources. Usually, maps cover continents, countries, or specific zones.
  3. Layers of related geospatial data. In addition to the solar radiation data, additional references are needed by a proper identification of the place of interest. This is at least: boundaries, regional limits, roads, city centers, power grids, main water features…
  4. Accuracy / uncertainty of the geospatial data. This parameter can vary among the parameters. The uncertainty can apply to the value or to the geospatial location.
  5. Time resolution. Usually, maps values are considered near to static values for a specific period. This is the case in most of the geographical parameters like road or mountains. But in the case of meteorological variables as is the case of solar radiation, maps must be referred to a specific year, month or related to an estimated long period. In addition to static values, series of maps can be available at a zone or a specific point.
    • Applications of series of maps can be included in the case of nowcasting and forecasting systems.
    • Applications of series of a specific point are addressed in the sections 3MODELED SOLAR RADIATION AND METEOROLOGICAL PARAMETERS and 4LONG TERM REPRESENTATIVE TIME SERIES IN A SPECIFIC LOCATION(Boilley & Wald, 2015).

(E) System or plant operation

In the case of big plants, there are nowcasting and forecasting services that uses solar radiation maps with high spatial and time resolution. These services are needed for a real-time control and operation of the plant.

Minimum or recommended values for the relevant specification items:

  • Spatial resolution: grid size of 100m x 100m
  • Region covered: power plant level.
  • Layers of related geospatial data: power plant lay out.
  • Uncertainty of solar radiation data: ≤ 10 %
  • Time resolution: 10 minutes.

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