Tracker Availability
Description
Tracker availability KPIs quantify how often each tracker row is correctly following its expected angle.
Two daily reports are generated:
- Row vs Row Setpoint – compares each row’s measured position to its own controller setpoint.
- Row vs Zone Median Setpoint – compares each row’s position to the median setpoint of all rows in its zone.
A row is considered available when the absolute position error is within an acceptable tolerance. These KPIs surface drifted trackers, stow-logic faults, communication drop-outs, and other issues.
Parameters (default values)
| Parameter | Purpose | Default |
|---|---|---|
| Available Max (deg) | Max position error allowed to count as “available”. | 5° |
| Irradiance Min (W/m²) | Minimum plane-of-array irradiance required to evaluate availability. | 0 W/m² |
| Exclude Stow Periods | If TRUE, stow periods are removed from the analysis. If a project lacks stow data this flag is ignored. | TRUE |
| Maximum Setpoint Change (deg) | Quality gate that rejects 5-min setpoint jumps above this value. | 60° |
Filters
Before availability is calculated, any 5-minute interval is discarded if any of the following are true:
- Tracker position or setpoint is blank.
- Plane-of-array irradiance ≤ Irradiance Min.
- Exclude Stow Periods is TRUE and the tracker zone is reported as stowed.
- |Position − Setpoint| ≥ 120°.
- |Setpoint(t) − Setpoint(t-1)| > Maximum Setpoint Change. (Rule 5 is skipped for the first sample of the day.)
Method 1 – Row vs Row Setpoint
- Query 5-minute tracker position, tracker setpoint, met station poa, and tracker zone status for every row in the project.
- Apply filters listed above to build the valid-data mask.
- Calculate position error
[ \Delta\theta*{\text{row}}(t)=\left|\text{Position}*{\text{row}}(t)-\text{Setpoint}_{\text{row}}(t)\right| ] - Compute availability for each row
[ A*{\text{row}}=\frac{\text{count}\left(\Delta\theta*{\text{row}}\le\text{Available Max}\right)} {\text{count(valid samples)}} ] - Export an Excel workbook containing:
- Parameters – editable inputs & descriptions.
- Availability – one value per row (percent).
- Difference – per-sample (\Delta\theta_{\text{row}}) table.
- Raw data sheets: Position, Setpoint, Stow, Irradiance.
Method 2 – Row vs Zone Median Setpoint
- Derive zone setpoints by taking the median of all row setpoints within each zone at every 5-minute timestamp.
- Repeat Steps 2-5 from Method 1, replacing Setpoint₍row₎(t) with Setpoint₍zone median₎(t) in the error formula.
- The workbook layout is identical; the Setpoint sheet now shows zone medians (prefixed “Zone”).
Usage Notes
- All calculations occur in the exported Excel file via formulas, allowing users to adjust parameters post-hoc.