Availability

Availability expresses the proportion of time that a system is actively producing energy at or above its minimum operational threshold, compared to the expected production time.

Availability is a crucial KPI to analyze the performance of PV assets, as a minimum value is usually required to comply with regulatory authorities, grid operators, and contractual obligations.

Availability calculation

To calculate time-based availability, GPM Horizon uses the following parameters and variables:

Uptime:
- AC Power is at least 1% of the nominal AC power.
- Nominal AC Power: project-specific, provided by your organization during the configuration process.
  Note: If the AC power is less than 1% of the nominal power, but irradiance is above the minimum threshold, the system may not be technically available. This may suggest that there is a technical issue or that performance is sub-optimal.
Irradiance uptime (minutes): minimum threshold is 100W/m².

GPM Horizon calculates the capacity factor using the following formula:

$A v a i l a b i l i t y (%) = (\frac{U p t i m e}{I r r a d i a n c e u p t i m e}) \times 100$

Aggregation methods

At each level of the portfolio, GPM Horizon aggregates and ponders the data used for the calculation, to provide relevant metrics at each level while preserving accuracy and reliability.


Level	Aggregated variables
Device	Device-level data is used directly to apply the formula.
Site	Site availability Sum of device-level availability (combined uptime/downtime of all devices)
Portfolio	Combined availability of all sites in the portfolio.