Vaisala Energy Support
What is Direct Normal Irradiance?
Direct Normal Irradiance (DNI) is the amount of solar radiation received per unit area by a surface that is always held perpendicular (or normal) to the rays that come in a straight line from the direction of the sun at its current position in the sky. Typically, you can maximize the amount of irradiance annually received by a surface by keeping it normal to incoming radiation. This quantity is of particular interest to concentrating solar thermal installations and installations that track the position of the sun.
If you are interested in more detailed information on the DNI values for any location worldwide, please see our 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?
- What is Global Horizontal Irradiance?
- How can I compare sites side-by-side?
- 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.