Defined term
Solar irradiance
Solar irradiance is solar power incident on a surface per unit area at a particular time.
Also known as solar irradiance at the array
measurement · Concept code GS-CONCEPT-032 · Last verified August 20, 2026
Definition and boundaries
Definition
Solar irradiance is solar power incident on a surface per unit area at a particular time.
Definition claim verification: Verified August 20, 2026
In plain language
When comparing Solar irradiance, keep the unit, time period, measurement boundary, and underlying assumptions the same on both sides.
What it is not
It is not energy accumulated over a day or year and it is not photovoltaic electrical output.
Decision context
Why it matters
A production model needs the relevant weather data and plane or surface definition rather than a generic statement that a location is sunny.
Decision-context claim verification: Verified August 20, 2026
Information boundary
This page provides general educational context, not a site design, production guarantee, utility determination, contract interpretation, legal opinion, tax conclusion, or individualized financial advice. Verify property, equipment, utility, jurisdiction, program, and agreement details before acting.
Concept relationships
Affects
- Annual solar productionPublished conceptSolar irradiance can affect how Annual solar production is evaluated
Primary sources
- National Laboratory of the Rockies: PVWatts Version 8 API
Revision PVWatts API 8.0 · website 8.5.2 · Source event as of September 25, 2025 · Ontology accessed August 20, 2026 · Ontology verified August 20, 2026
What to do next
- Open the related GeoStellar guideNext step
- Return to the Solar Energy WikiNext step
- Estimate a residential solar systemNext step