Defined term
Photovoltaic system loss
Photovoltaic system loss is a modeled or measured reduction between an identified reference energy and delivered photovoltaic energy attributable to specified loss mechanisms.
Also known as PV system loss
measurement · Concept code GS-CONCEPT-040 · Last verified August 20, 2026
Evidence through 2025-09-25 · 0 sources have no source-event date
Content modified 2026-08-20
Definition and boundaries
Definition
Photovoltaic system loss is a modeled or measured reduction between an identified reference energy and delivered photovoltaic energy attributable to specified loss mechanisms.
Definition claim verification: Verified August 20, 2026
In plain language
When comparing Photovoltaic system loss, keep the unit, time period, measurement boundary, and underlying assumptions the same on both sides.
What it is not
It is not one universal percentage applicable to every design or site.
Decision context
Why it matters
Loss categories, calculation order, overlap, period, reference boundary, and included inverter treatment must be stated instead of adding unrelated percentages blindly.
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.
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Learning navigation
Primary topic: Performance
Broader topic
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Builds toward
- Photovoltaic performance ratioPublished concept
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
- National Renewable Energy Laboratory: PVWatts Version 5 Manual
Revision NREL/TP-6A20-62641 · Source event as of September 1, 2014 · Ontology accessed August 20, 2026 · Ontology verified August 20, 2026