Capacity Utilisation Factor (CUF)
The share of nameplate a plant actually delivered over time.
Capacity Utilisation Factor (CUF), also called capacity factor, is the energy a plant produced as a fraction of what it would produce running at full nameplate every hour of the period. For fixed-tilt PV it is typically 15–25%, capped by day/night and the sun’s arc. It is widely used in tenders and PPAs, though it conflates resource with performance.
Definition
CUF = actual energy ÷ (rated power × hours in period). Because the sun shines part of the day and at varying angles, even a flawless PV plant has a CUF well below 100%. Trackers and sunnier sites raise it. Unlike PR it does not separate the resource from plant health, so it is a contract/headline metric rather than a diagnostic.
Formula
CUF (%) = energy produced ÷ (rated capacity × hours in period) × 100
Typical range
Fixed-tilt PV: ~15–20%. Single-axis trackers or high-irradiation sites: ~20–28%. The figure is structurally capped by the day-night cycle and solar geometry, so a "low" CUF is normal for PV and should be read against regional norms.
Why it matters
CUF appears in government tenders, PPA terms and investor reporting because it is simple and comparable across technologies. But two plants with identical CUF can have very different PR — one sunnier, one better-run. Operators need both: CUF for the contract, PR to know what is actually fixable.
How NuraVolt tracks it
NuraVolt reports CUF alongside PR and specific yield so the contract-facing number is never read in isolation: when CUF dips, the platform shows immediately whether PR held (a weaker resource period) or fell (a plant issue worth a truck roll).
Frequently asked questions
See also
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