Plant availability
How much of the time the plant was actually able to produce.
Plant availability is the share of time (often weighted by potential generation) that a plant was able to produce, excluding downtime from inverter trips, grid curtailment, or maintenance. Energy-weighted availability — which counts a midday outage far more heavily than a dawn one — is the figure that matters and the one O&M guarantees are usually written against.
Definition
Time-based availability is simply uptime ÷ total time. Energy-based (or production-weighted) availability weights each outage by the energy that would have been generated then, so an inverter down at noon costs far more than the same outage at dusk. O&M contracts typically guarantee energy-based availability above a threshold, with bonuses or penalties attached.
Formula
Energy availability (%) = (potential − lost energy) ÷ potential × 100
Typical range
Contracted O&M availability guarantees commonly sit at 98–99%+ on an energy-weighted basis. Sustained availability below the contracted floor triggers penalties; the gap between time- and energy-based figures reveals whether outages cluster in high-value hours.
Why it matters
Availability is where O&M performance is rewarded or penalised, and a single mid-day inverter outage left unattended can blow a monthly guarantee. Separating availability loss from efficiency loss is essential: a healthy PR with poor availability is an uptime/response problem, not a degradation problem.
How NuraVolt tracks it
NuraVolt computes energy-weighted availability from inverter and meter status, attributes downtime to cause (inverter trip, grid curtailment, planned maintenance), and ranks outages by the generation they cost — so response is prioritised by euros lost, and the figure is contract-ready.
Frequently asked questions
See also
The headline efficiency number for a PV plant, independent of weather.
The share of nameplate a plant actually delivered over time.
Actual generation measured against a physics model of what the plant should have made.
A common driver of mid-day inverter downtime.
See this on your own plants
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