This document is a catalog of all operational events detected and recorded by Performance+ for solar sites. Events are structured, time-stamped records that describe notable conditions at the site, inverter, or weather station level. They appear in the BazeField interface and are used to contextualise performance losses, support root-cause analysis, and guide O&M decisions.
Section 1 covers site-level communication events. Section 2 details all inverter events, grouped into AC-side primary events, AC-side secondary events, DC-side events, other events, and soiling events. Section 3 covers weather station sensor health events. For a detailed explanation of how raw condition flags are assembled into events, see Event Detection.
Three categories of objects are monitored:
- The site - for communication reliability
- Inverters - for AC-side, DC-side, and environmental conditions affecting yield
- Weather stations - for sensor health and data quality
1. Site Events
| Event | Trigger | Min Duration | Max Gap Merged | Bridge Conditions (max duration) |
|---|---|---|---|---|
| Communication Issue | SCADA data transmission interrupted (data logger, modem, or network link offline) | 30 min | 15 min | None |
2. Inverter Events
Evaluated at 5-minute resolution. Events are grouped into three families based on which side of the inverter is affected.
2.1. AC-Side Events (primary)
Only one primary AC condition is assigned per timestamp. Higher-severity conditions take precedence over lower ones; the priority order from highest to lowest is: Down > Grid Curtailment > Site Clipping > Inverter Clipping > Power Limit.
| Event | Trigger | Min Duration | Max Gap Merged | Bridge Conditions (max duration) |
|---|---|---|---|---|
| Inverter Down | No AC production while irradiance is available | 15 min | 10 min | Nighttime, Comm issue (18 h) |
| Grid Curtailment | TSO/DSO instruction to reduce injected active power | 30 min | 15 min | Nighttime, Comm issue, Inv Down (18 h) |
| Site Clipping | Site transformer or grid-connection capacity caps total AC output | 15 min | 15 min | Comm issue, Inv Down, Grid Curtailment (6 h) |
| Inverter Clipping | Inverter's own AC power rating reached before DC input is fully utilised | 15 min | 15 min | Comm issue, Inv Down, Grid Curtailment, Site Clipping (6 h) |
| Inverter Power Limit | External active-power setpoint from a plant power controller or SCADA constrains output below the natural operating point | 30 min | 15 min | Nighttime, Comm issue, Inv Down, Grid Curtailment, Site Clipping, Inv Clipping (18 h) |
2.2. AC-Side Events (secondary)
These events capture losses detected independently of the primary AC status. They can only occur while the inverter is actively producing power. Because they are tracked on a separate channel from the primary AC condition, a secondary event can overlap a primary event in time, the single-primary-per-timestamp rule in Section 2.1 applies only within the primary channel, not between primary and secondary events.
| Event | Trigger | Min Duration | Max Gap Merged | Bridge Conditions (max duration) |
|---|---|---|---|---|
| Reactive Power Loss | Inverter supplies reactive power (Q) to meet a grid power-factor or voltage-regulation requirement, reducing the headroom for active power | 30 min | 15 min | Comm issue, Inv Down (6 h) |
| Max kVA Limit | Inverter's apparent-power (kVA) rating caps simultaneous active and reactive output before the active-power rating is reached | 30 min | 15 min | Comm issue, Inv Down (6 h) |
| Inverter Thermal Derating | Inverter's internal protection reduces output power due to overheating of the power electronics | 30 min | 15 min | Comm issue, Inv Down (2 h) |
2.3. DC-Side Events
These events describe array-side conditions. Detection relies on the inverter actively producing power, so these events cannot be observed at night or when the inverter is down.
| Event | Trigger | Min Duration | Max Gap Merged | Bridge Conditions (max duration) |
|---|---|---|---|---|
| Tracker Wind Stow | Single-axis trackers rotate to a horizontal safety position due to wind speed exceeding the site threshold, reducing effective irradiance on modules | 30 min | 15 min | Comm issue, Tracker Non-Wind, Inv Down (6 h) |
| Tracker Non-Wind Deviation | Tracker deviates from the modelled backtracking trajectory for a non-wind reason (mechanical fault, motor failure, communication loss, manual override) | 60 min | 30 min | Comm issue, Nighttime, Inv Down (18 h) |
2.4. Other Inverter Events
| Event | Trigger | Min Duration | Max Gap Merged | Bridge Conditions (max duration) |
|---|---|---|---|---|
| Snow | Snow accumulation on module surface reduces DC output to near-zero; detected using on-site measurements combined with satellite snowfall data | 60 min | 30 min | Comm issue, Nighttime (18 h) |
2.5. Soiling Events
Evaluated at daily resolution. Soiling level and accumulation rate are estimated per inverter by the soiling analysis module. No bridging is applied - a break in soiling conditions is taken at face value.
| Event | Trigger | Min Duration | Max Gap Merged | Bridge Conditions |
|---|---|---|---|---|
| Soiling Level High | Cumulative soiling on the modules exceeds 15%, meaning at least 15% of potential yield is being lost to soiling at the time of assessment | 1 day | 1 day | None |
| Soiling Rate High | Daily soiling accumulation rate exceeds 0.5% per day while the cumulative soiling level is already between 5% and 15% - indicating the site is accumulating dirt fast enough to warrant attention before the high-level threshold is reached | 1 day | 1 day | None |
3. Weather Station Events
Evaluated at daily resolution. Each health flag is assessed independently per sensor instance. All weather station events share the same timing parameters: minimum 1 day, max gap merged 2 days, communication outages bridged up to 3 days.
The sensor types monitored are: Irradiance POA, Irradiance GHI, Ambient Temperature, Module Temperature, and Wind Speed.
| Health Flag | Affected Sensor Types | Trigger |
|---|---|---|
| Low Data Quality | All | An insufficient number of valid measurements was recorded during the day, making the sensor's daily output unreliable for performance analysis |
| Sensor Deviation | All | Sensor readings differ significantly from peer sensors of the same type on the site, or deviate substantially from a clear-sky or model reference |
| Sensor Misconfiguration | All | The sensor correlates more strongly with a different physical quantity than it should measure (e.g. a POA sensor reading more like a horizontal GHI sensor, or a module temperature sensor behaving like an ambient temperature sensor) |
| Satellite Bias | Ambient Temperature only | The sensor's daily average reading differs from the satellite-derived ambient temperature reference by more than an acceptable hard threshold, indicating a systematic calibration or installation offset |
| Temperature Model Regression Issue | Module Temperature only | The relationship between the sensor and the irradiance/temperature prediction model falls outside the expected regression range, which can indicate a partially detached sensor or a systematic installation error |