Solar Suitability Index (SSI™) – Continuous Score (1-100)

Solar Suitability Index (SSI™) – Continuous Score (1–100)

Global | ~1 km Resolution | 2020–2024

Raster Name

Solar Suitability Index (SSI™) – Continuous Score

File Name

solar_suitability_index_2020_2024_web_1km.tif

Short Description

A continuous global solar suitability score (0–100) representing the relative favorability of locations for solar energy development based on multi-parameter climatological conditions.

Units of Measure

Index Score (0–100, dimensionless)

Technical Specification

This dataset represents a continuous global solar suitability index developed by AtmosphericIQ LLC using a proprietary multi-parameter analysis of atmospheric and radiative conditions derived from ERA5 reanalysis data.

The SSI™ integrates key variables influencing solar energy performance and reliability, including:

• Global Horizontal Irradiance (GHI)
• Clear-sky irradiance conditions (GHIcs)
• Beam (direct) irradiance (BHI)
• Cloud cover (TCC)
• Total Column Water Vapour (TCWV)
• Surface pressure (SP)
• Air temperature at 2 meters (T2M)
• Wind speed
• Relative humidity (RH)

Each input raster was normalized to a common 0–1 scale using global climatological bounds and combined using a weighted linear model:

SSI™ = 100 × Σ (wᵢ · Sᵢ)

where:

• wᵢ = weighting factor for variable i
• Sᵢ = normalized sub-score (0–1)

Positive contributors (e.g., irradiance) increase suitability, while negative contributors (e.g., cloud cover, humidity, temperature) reduce suitability.

Classification

These classification thresholds are fixed and globally consistent, allowing direct comparison across geographic regions.

Under the current 2020–2024 climatology, observed SSI™ values typically range from approximately 15 to 84, with the highest-performing global solar environments occurring within Classes 6 and 7.

Key Characteristics

• Continuous global index scaled from 0 to 100
• Higher SSI™ values indicate more favorable solar resource conditions
• Lower SSI™ values indicate reduced solar potential due to atmospheric or environmental limitations

Under the current 2020–2024 climatology, the observed maximum SSI™ is approximately 84, indicating that the model is conservatively scaled and no regions reached the theoretical maximum.

Spatial Characteristics

• Coordinate System: GCS_WGS_1984
• Spatial Resolution: ~1 km
• Coverage: Global (±85.0511° for web compatibility)

Processing

The SSI™ dataset was developed by AtmosphericIQ LLC and processed for distribution and deployment by Engineering Director, Inc.

ERA5-derived climatological rasters (2020–2024) were normalized and combined using a weighted multi-criteria scoring model. The resulting SSI™ was scaled to a 0–100 range, reprojected to GCS_WGS_1984, resampled to ~1 km resolution, and exported as GeoTIFF for analytical and web-based applications.

Model Validation

The Solar Suitability Index (SSI™) was evaluated against independent solar performance datasets to confirm its reliability as a global screening and comparison tool.

Validation Approach

Validation was performed by comparing SSI™ values against the Global Solar Atlas photovoltaic power potential (PVOUT) dataset, which represents long-term average solar energy production potential (kWh/kWp) based on independent modeling methodologies.

A set of 9,864 globally distributed sample points was generated, and SSI™ values were extracted and compared directly with PVOUT values after spatial alignment to a common grid.

Validation Results

• Pearson Correlation (r): 0.929
• Coefficient of Determination (R²): 0.863
• Sample Count: 9,864

Interpretation

The results demonstrate excellent agreement between the Solar Suitability Index (SSI™) and independent photovoltaic performance estimates.

An R² value of 0.863 indicates that the SSI™ explains approximately 86% of the variation in photovoltaic power potential globally. This confirms that the SSI™ effectively captures the combined influence of solar irradiance, atmospheric attenuation, and environmental conditions on solar energy suitability.

Model Behavior

The SSI™ correctly identifies high-suitability regions such as:

• Sahara Desert
• Arabian Peninsula
• Atacama Desert
• Southwestern United States
• Interior Australia

It also identifies lower suitability regions characterized by:

• persistent cloud cover
• high atmospheric moisture
• elevated humidity or temperature constraints

This spatial consistency further supports the physical validity of the model.

Scope and Intended Use

The Solar Suitability Index (SSI™) is a relative scoring model designed for:

• global solar resource screening
• comparative site evaluation
• portfolio analysis
• geospatial decision support

The SSI™ is not intended to predict exact system output, but rather to provide a normalized, globally consistent measure of solar suitability based on climatological conditions.

Data Access & API Services

The SSI™ dataset is developed by AtmosphericIQ LLC and made available through Engineering Director, Inc. platforms.

Interactive map access, API integration, bulk-scoring, and enterprise lookup services are available at:
www.engineeringdirector.com

Use of the SSI™ dataset beyond visual interpretation, including API access, bulk-scoring, automated queries, or integration into external systems, is subject to the Engineering Director API Terms of Service.

Related SSI™ Datasets

Additional Solar Suitability Index (SSI™) products are available at multiple classification levels and spatial extents.

• Regional Solar Suitability Index (SSI™) – Index (1–7)
  View Interactive Map
  Regionally clipped categorical suitability dataset for focused analysis.


• Global Solar Suitability Index (SSI™) – Index (1–7)
  View Interactive Map
  Discrete global classification derived from the continuous SSI™ model.


• Global Solar Suitability Index (SSI™) – Continuous Score (1–100)
  View Interactive Map
  Full-resolution continuous global suitability model.

Supporting Climatic Input Layers

The following climatic layers represent key environmental inputs used in the development of the Solar Suitability Index (SSI™) model. These layers are provided as companion visualization datasets.

All SSI™ datasets are derived from a proprietary multi-parameter model developed by AtmosphericIQ LLC.

• Global Horizontal Irradiance (GHI – Mean Irradiance)
  View Interactive Map


• Clear-Sky Global Horizontal Irradiance (GHIcs)
  View Interactive Map


• Beam Horizontal Irradiance (BHI – Mean Irradiance)
  View Interactive Map


• Clear-Sky Beam Horizontal Irradiance (BHIcs)
  View Interactive Map


• Total Cloud Cover (TCC)
  View Interactive Map


• Total Column Water Vapour (TCWV)
  View Interactive Map


• 2-Meter Air Temperature (T2M)
  View Interactive Map


• Surface Pressure (SP)
  View Interactive Map


• Wind Speed
  View Interactive Map


• Mean Annual Relative Humidity (RH)
  View Interactive Map

Legal & Licensing

© 2026 AtmosphericIQ LLC and Engineering Director, Inc. All rights reserved.

SSI™ is a trademark of Engineering Director, Inc.

This dataset and associated models are proprietary to AtmosphericIQ LLC and distributed by Engineering Director, Inc.

No part of the SSI™ dataset may be reproduced, distributed, or used for commercial purposes without prior written permission from AtmosphericIQ LLC or Engineering Director, Inc.

The SSI™ dataset is provided "as is" without warranty of any kind. AtmosphericIQ LLC and Engineering Director, Inc. make no representations regarding accuracy, completeness, or fitness for a particular purpose. Users assume all risk associated with its use.

Dataset Citation

Mazzella, J. (2026).
Global Solar Suitability Index (SSI™) – Continuous Score, 2020–2024.
AtmosphericIQ LLC / Engineering Director, Inc.

Based on ERA5 reanalysis data:

Hersbach, H., et al. (2020).
The ERA5 global reanalysis.
Quarterly Journal of the Royal Meteorological Society, 146(730), 1999–2049.

ECMWF Copernicus Climate Data Store (CDS)
https://cds.climate.copernicus.eu