Vaisala Energy Support
What is Global Horizontal Irradiance?
The radiation reaching the earth's surface can be represented in a number of different ways. Global Horizontal Irradiance (GHI) is the total amount of shortwave radiation received from above by a surface horizontal to the ground. This value is of particular interest to photovoltaic installations and includes both Direct Normal Irradiance (DNI) and Diffuse Horizontal Irradiance (DIF).
DNI is solar radiation that comes in a straight line from the direction of the sun at its current position in the sky. DIF is solar radiation that does not arrive on a direct path from the sun, but has been scattered by molecules and particles in the atmosphere and comes equally from all directions.
If you are interested in more detailed information on the GHI values for any location worldwide, please see our Solar Prospecting Tools, Solar GIS Data Layer, Solar Time-series, and Solar Site Climate Variability Analysis products.
More Solar Online Tools Questions
- How do I enter a location?
- What's the latest month available in the solar time series tool?
- What is the Data Shown in the Solar Time Series Viewer?
- What updates were applied to the datasets in November 2019?
- Which weather data source should I pick?
- What do the Annual Mean Irradiance Tools provide?
- How do I interpret the graphs provided by the Monthly Mean Irradiance Tools?
- What solar values are shown on the map?
- Why do we show a +/- next to the annual values?
- How can I compare sites side-by-side?
- What is Direct Normal Irradiance?
- How do I change locations for individual tools?
- What is Diffuse Horizontal Irradiance?
- Why does the map disappear?
- What are the units of irradiance?
- What affects solar radiation at a given site?
- How much area is covered by the Solar Prospecting Tools?
- How accurate are the Solar Prospecting Tools?
- What data has been created?
- How was the data behind your map created?
- How do I convert the 3TIER values to peak sun hours?
- Why does the data not match my observations?
- What were 3TIER's solar data validation procedures?
If you didn't find what you were looking for, please contact 3TIER Support for additional assistance.