Terrain models

  • Updated on Jan 21, 2025
  • Published on Nov 29, 2024
  • 3 minute(s) read
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In this document

We highlight the importance of accurate terrain information for the successful development of solar energy projects. For utility-scale solar power plants located in complex terrains, features like hills and slopes necessitate detailed analysis to achieve optimal design and engineering.

Overview

By accounting for site-specific topography, simulations can provide precise insights into energy yields, enabling informed decision-making and maximizing the efficiency of solar installations.

Thanks to the processing of digital terrain models, a comprehensive terrain characterization can conducted for each site using data on elevation (ELE). Based on this parameter, surface slope (SLO), and surface azimuth (AZI) are calculated.

On the other hand, horizon data (HOR) is generated by aggregating points from the surrounding terrain into a 360º orientation series around the site. This analysis enables the estimation of potential energy losses due to shading from nearby hills or mountains.

Elevation above sea level is also a crucial parameter to determine atmospheric thickness, which directly affects solar irradiance modeling.

Although digital terrain provide detailed information globally, to do a complete shadow analysis it is necessary to include local features, buildings, and other objects. To do so, more detailed surface models and 3D modeling tools are needed.

Solar project developers usually combine terrain information with other geo-data layers like land cover and population that provide useful information for studying project feasibility.

Calculation of slope and azimuth data

A Digital Elevation Model (DEM) is a 3D representation of terrain created from elevation data, offering a detailed depiction of the Earth's topography. It maps land elevation at regular intervals, typically in a grid format, providing essential insights for accurate analysis and decision-making in solar project development.

Using high-resolution DEMs, slope and azimuth data—critical auxiliary parameters to elevation—are derived through our proprietary in-house methodology. These parameters enable precise identification of flat surfaces and areas with inclinations. When an inclined surface is identified at a project site, further analysis can be conducted to determine the optimal design of the photovoltaic (PV) system, ensuring efficient and cost-effective project implementation.

Solargis database features DEM data at the resolution of 3 arcsec (nominally 90 m) on the land and 30 arcsec (nominally 1 km) for the sea bottom.  This is satisfactory for the regional analyses of the terrain structures in the neighborhood (for example, shading from surrounding mountains or hills).

The data processing procedure

The final dataset is the result of rigorous patching of a few available terrain datasets:

  1. Shuttle Radar Topography Mission (SRTM)

  2. Viewfinder Panorama

  3. Global Digital Elevation Model

  4. Gridded Bathymetry Data

For land areas, primary dataset [1] is implemented. Dataset [2] is used to fill the lands above 60°N and below 60°S, and to fix or improve the identified problems in the dataset [1]. In a few cases of insufficient quality of [1] and [2], dataset [3] was post-processed and implemented. We have also tackled many issues in elevation data along the coastline. Finally, for sea bottom elevations, data source [4] is implemented.

Modeling detailed surface objects

When data from Digital Surface Models (DSM) are available, it becomes possible to analyze the highest solid surfaces, including built-up structures and dense vegetation. This is particularly useful for detailed shading analyses in urban environments, such as assessing rooftop PV potential. For such analyses, a nominal resolution of approximately 10 cm or similar is recommended to ensure precision.

Since achieving globally uniform solutions for detailed surface modeling is challenging, the most common approach involves creating manual 3D models for individual sites using specialized simulation software like Evaluate. This site-specific 3D modeling is critical for solar PV projects, enabling accurate energy yield estimation, comprehensive shading analysis, and space optimization. By developing detailed 3D representations of the project site, the software assists in determining the optimal placement and configuration of solar panels to maximize energy production.

Simulation software streamlines this process by importing site data and generating 3D terrain models. It allows for the addition of solar panels and potential obstructions, such as buildings or trees, to perform shading and sun path analyses. These analyses predict energy production over time, providing valuable insights for project planning.

Through iterative design adjustments and performance simulations, solar energy modeling software facilitates the optimization of solar installations, ensuring efficient use of space and maximizing energy output.

Further reading