Solar Irradiance

Solar irradiance is the instantaneous power of sunlight falling on a surface, measured in watts per square metre (W/m²). Standard test conditions for rating panels assume 1,000 W/m².

Irradiance integrated over a day gives irradiation (kWh/m²/day), which equals peak sun hours numerically. India’s annual global horizontal irradiation ranges roughly from 1,600 to over 2,200 kWh/m² — among the best solar resources of any large economy.

Part of the HUM Solar Glossary — 75+ plain-language definitions for India’s solar ecosystem, maintained as a neutral reference. Browse all terms →