LocusNOC allows users to take full advantage of the Performance Index (PI) Alert. This functionality allows customers to easily set value, time, and buffer thresholds to enable alerts of underperforming meters and inverters. PI leverages advances in the platform's modeling capabilities in order to deliver a reliable and accurate metric.
Alert Settings
These settings can be accessed through the LocusNOC config page. PI is calculated as the ratio of measured power and modeled power. All alerts are based off the hourly granularity of these inputs.
Performance Index Value
Value threshold for triggering a PI alert. Hourly PI values must be below this threshold for longer than the threshold hours to trigger an alert. Allowed values are 0.0 to 1.0. Default value: 0.8
Performance Index Threshold (daylight hours)
The PI condition must continue for the time period defined by the threshold before generating an alert. Only daylight hours are considered. Allowed thresholds are 1 to 168. Default time: 2 hours
Performance Index Buffer
Buffer period after sunrise and before sunset to ignore PI alert conditions. Allowed values are 0.0 to 4.0. Default buffer: 0 hours
An alert will be created if the hourly PI is less than the value threshold for longer than the time threshold, considering only "daylight" hours. Data outside of daylight is ignored. "Daylight" hours considers sunrise + buffer until sunset - buffer.
Example Scenario
A component is set up with the default settings of 80%, a 2 hour threshold, and no buffer. This component doesn't currently have any open alerts. On this day, sunrise is at 7:29 and sunset at 17:21. The alert generator runs every 4 hours at 0:05, 4:05, 8:05, etc. Our timeseries data is:
ts 7:00 8:00 9:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 PI 85% 79% 75% 85% 99% 100% 100% 100% 100% 75% 75% 60%
8:05 - Because sunrise is at 7:29, the hour of 7:00 is excluded from the analysis. The hour of 8:00 is also excluded during this run because it is only 5 minutes into the 8:00 hour. No alert changes.
12:05 - The hours of 8:00, 9:00, 10:00 and 11:00 can now be analyzed. Because PI for 8:00 and 9:00 are below the threshold, and the two hour time threshold was exceeded, an alert with start time of 8:00 is created. At 10:00 PI increases, the alert is closed with an end time of 10:00. This alert would be created around 12:05 and the customer would receive an email notification within 5 minutes of creation, around 12:10.
16:05 - PI for 12:00, 13:00, 14:00 and 15:00 is analyzed. All values exceed the threshold, no alerts are created.
20:05 - Because sunset is 17:21, the hour of 17:00 is not applied to the calculation because it does not contain a full hour of daylight. The hours after 17:00 are also not applicable because they are after sunset. The hour of 16:00 is analyzed, which has a PI under the threshold, however, an alert is not created because the time threshold of 2 hours has not yet been exceeded. If the next day starts with an hour of PI under the threshold, an alert would be created with a start time of 16:00.
FAQ
Q: What granularity does the PI alert use?
A: The PI alert is based off hourly granularity. The calculation is therefore comprised of the hourly values of measured and modeled power for a given period. In order to investigate PI alerts, it is recommended to view results in hourly granularity.
Q: How often does the alert generator run?
A: Every four hours (six times per day).
Q: What are the requirements?
A: There are two main requirements:
The site must be communicating and sending data to the Locus servers
The component must be configured to have Performance Index as an available data field. This requires two things:
The component must have a data reading for Measured AC Power (kW).
The component must be configured with a PV Model to calculate Modeled AC Power (kW). See “Enhanced PV Modeling” Article for more information and troubleshooting.
Q: What will happen to my alerts that were open in the old Performance Yield alert?
A: Any Performance Yield alerts that are open at the time of the transition will be closed. These alerts will be reopened as Performance Index alerts if conditions are still valid.
Q: What is the difference between the Performance Index data field and the Performance Index Alert?
A: The PI data field is used to determine whether a PI Alert should open or close. The PI data field, is a data field that can be viewed in the charting tool, reporting interface, Datalink, or external api. The PI Alert, is an alert that is available to view in the fleet view, alerts table, email notifications, etc.
Q: Where can I find Performance Index in the LocusNOC charting tool?
A: In the charting tool, Performance Index can be found on the left hand side of the screen under Modeled Data.
Q: Where can I find Performance Index in the LocusNOC reporting tool?
A: In the New Reporting Interface, select your site using the search box in the top left. Performance Index can be found under Modeled Data