--- description: What is Irradiance: It refers to the power of electromagnetic radiation, such as light or heat, that is received per unit area on a surface. title: What is Irradiance? - Energy Theory image: https://energytheory.com/wp-content/uploads/2023/04/JAN23-What-is-Irradiance.jpg --- [ Close Menu ](#) * [About](https://energytheory.com/about-us/) * [EV](https://energytheory.com/category/electric-vehicles/) * [FAQs](https://energytheory.com/category/faqs/) * [Glossary](https://energytheory.com/category/glossary/) * [Green](https://energytheory.com/category/green/) * [Renewable](https://energytheory.com/category/renewable/) * [Sustainable](https://energytheory.com/category/sustainable/) * [Energy Economy](https://energytheory.com/category/energy-economy/) * [Energy Services](https://energytheory.com/category/energy-services/) * [Solar](https://energytheory.com/category/solar/) * [Sustainable](https://energytheory.com/category/sustainable/) * [News](https://energytheory.com/category/latest-news/) * [Language](#) [ ![Energy Theory](https://energytheory.com/wp-content/uploads/2022/11/2e3rtgthghnm.png) ](https://energytheory.com/ "Energy Theory") ![en](https://cdn.gtranslate.net/flags/svg/en.svg)English [![es](https://cdn.gtranslate.net/flags/svg/es.svg) Spanish](#) [![fr](https://cdn.gtranslate.net/flags/svg/fr.svg) French](#) [![en](https://cdn.gtranslate.net/flags/svg/en.svg) English](#) [![it](https://cdn.gtranslate.net/flags/svg/it.svg) Italian](#) [![zh-CN](https://cdn.gtranslate.net/flags/svg/zh-CN.svg) Chinese (Simplified)](#) [![nl](https://cdn.gtranslate.net/flags/svg/nl.svg) Dutch](#) [![fi](https://cdn.gtranslate.net/flags/svg/fi.svg) Finnish](#) [![de](https://cdn.gtranslate.net/flags/svg/de.svg) German](#) [![hi](https://cdn.gtranslate.net/flags/svg/hi.svg) Hindi](#) [![ja](https://cdn.gtranslate.net/flags/svg/ja.svg) Japanese](#) [![pl](https://cdn.gtranslate.net/flags/svg/pl.svg) Polish](#) [![pt](https://cdn.gtranslate.net/flags/svg/pt.svg) Portuguese](#) [![ru](https://cdn.gtranslate.net/flags/svg/ru.svg) Russian](#) [ ![Energy Theory](https://energytheory.com/wp-content/uploads/2022/11/2e3rtgthghnm.png) ](https://energytheory.com/ "Energy Theory") ![en](https://cdn.gtranslate.net/flags/svg/en.svg)English [![es](https://cdn.gtranslate.net/flags/svg/es.svg) Spanish](#) [![fr](https://cdn.gtranslate.net/flags/svg/fr.svg) French](#) [![en](https://cdn.gtranslate.net/flags/svg/en.svg) English](#) [![it](https://cdn.gtranslate.net/flags/svg/it.svg) Italian](#) [![zh-CN](https://cdn.gtranslate.net/flags/svg/zh-CN.svg) Chinese (Simplified)](#) [![nl](https://cdn.gtranslate.net/flags/svg/nl.svg) Dutch](#) [![fi](https://cdn.gtranslate.net/flags/svg/fi.svg) Finnish](#) [![de](https://cdn.gtranslate.net/flags/svg/de.svg) German](#) [![hi](https://cdn.gtranslate.net/flags/svg/hi.svg) Hindi](#) [![ja](https://cdn.gtranslate.net/flags/svg/ja.svg) Japanese](#) [![pl](https://cdn.gtranslate.net/flags/svg/pl.svg) Polish](#) [![pt](https://cdn.gtranslate.net/flags/svg/pt.svg) Portuguese](#) [![ru](https://cdn.gtranslate.net/flags/svg/ru.svg) Russian](#) [Glossary](https://energytheory.com/category/glossary/) # What is Irradiance? By [Elliot Clark](https://energytheory.com/author/elliot%5Fclark/)November 17, 20232 Mins Read ![JAN23 What is Irradiance](https://energytheory.com/wp-content/uploads/2023/04/JAN23-What-is-Irradiance-1024x683.jpg "What is Irradiance?") Irradiance refers to the **power of electromagnetic radiation**, such as light or heat, that is **received per unit area on a surface**. It is a fundamental concept in physics and finds applications in various fields, including solar energy, atmospheric science, and optical engineering. It is typically expressed in units of watts per square meter (W/m²) and serves as a quantitative measure of the radiation that reaches a surface. Several factors, such as the angle of incidence, atmospheric conditions, and wavelength of the radiation, can influence it. For instance, the intensity of sunlight varies throughout the day due to variables like cloud cover and geographical location. In summary, it quantifies the radiant energy per unit area received on a surface and is utilized in diverse disciplines to characterize the power of electromagnetic radiation. ### **What is the Need for Irradiance?** It plays a crucial role in a wide range of fields and applications. Some of them are: * It is used to quantify the amount of sunlight received by solar panels or collectors in solar energy systems, to determine optimal illumination levels in lighting design for architectural and interior spaces. * In the medical field, it is used in [neonatal phototherapy](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4440981/). * Additionally, irradiance is employed in environmental monitoring for studying plant growth, carbon sequestration, and ecological processes. * Material testing also uses it to evaluate material performance in industries such as aerospace and electronics. * In radiation therapy, it is utilized to calculate the precise dosage for effective cancer treatment. * Photography and imaging rely on irradiance for exposure settings to capture high-quality images. * In horticulture, it is utilized to optimize plant growth in controlled environments. * Accurate measurements of irradiance are essential in [photovoltaic system](https://energytheory.com/bifacial-photovoltaic-systems-to-boost-production-in-the-near-future/) design to optimize panel orientation and energy production. Irradiance measurements are integral in environmental impact assessments to evaluate the potential impacts of development projects on local irradiance levels and ecosystems. Thus, it plays a vital role in diverse applications across various fields. **Recommended:** [What is Direct Normal Irradiance?](https://energytheory.com/what-is-direct-normal-irradiance/) Share. 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With a background in environmental science, he has a deep understanding of the issues facing our planet and is committed to educating others on how they can make a difference. #### Related Posts [![Post-consumer recycled (PCR) content](https://energytheory.com/wp-content/uploads/2024/04/Post-consumer-recycled-PCR-content.png "What is Post-Consumer Recycled (PCR) Content?")](https://energytheory.com/what-is-post-consumer-recycled-pcr-content/ "What is Post-Consumer Recycled (PCR) Content?") #### [What is Post-Consumer Recycled (PCR) Content?](https://energytheory.com/what-is-post-consumer-recycled-pcr-content/) April 9, 2024 [![Heating Seasonal Performance Factor (HSPF)](https://energytheory.com/wp-content/uploads/2024/02/Heating-Seasonal-Performance-Factor-HSPF.jpg "What is Heating Seasonal Performance Factor (HSPF)?")](https://energytheory.com/what-is-heating-seasonal-performance-factor-hspf/ "What is Heating Seasonal Performance Factor (HSPF)?") #### [What is Heating Seasonal Performance Factor (HSPF)?](https://energytheory.com/what-is-heating-seasonal-performance-factor-hspf/) February 3, 2024 [![What is Annual Fuel Utilization Efficiency (AFUE)](https://energytheory.com/wp-content/uploads/2024/02/What-is-Annual-Fuel-Utilization-Efficiency-AFUE.jpg "What is Annual Fuel Utilization Efficiency (AFUE)?")](https://energytheory.com/what-is-annual-fuel-utilization-efficiency-afue/ "What is Annual Fuel Utilization Efficiency (AFUE)?") #### [What is Annual Fuel Utilization Efficiency (AFUE)?](https://energytheory.com/what-is-annual-fuel-utilization-efficiency-afue/) February 2, 2024 [Add A Comment ](#) Leave A Reply [Cancel Reply](https://energytheory.com/what-is-irradiance/#respond) Save my name, email, and website in this browser for the next time I comment. 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