String alarms

Last modified: 2025-09-24

The string alarm detects power loss at the string combiner box (single string) and inverter (input) levels.

• The alarms compare working (reference) strings or inputs with other strings or inputs.

• A minimum percentage of nominal current must be flowing through the working string or input.

• If at least one string falls below a defined threshold, this is considered a power loss, and an alarm is triggered.

• For systems equipped with string combiner boxes, if all strings of one combiner box are outages, all the string alarms are grouped into a single string alarm. This minimizes the overall number of alarms.

Parameters

Severity: Define the desired severity for this alarm.

String current: Define your threshold for “no current”. The default is ≤ 0%.

Reference string current: Define the minimum percentage of nominal current that must be flowing to be considered a “working string”. The default is 10%.

Delay after first occurrence: If you configure a delay, an alarm will only be triggered in case of persistent incidents. This helps to avoid alarms for deviations that only occur for a short time.

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Example

Based on the settings in the screenshot below:

• An alarm with the severity “high” is triggered when at least one string measures 10% of its nominal current and at least one string measures no current for 30 minutes or more.

Troubleshooting: string alarms can not be activated

If you are not able to set up string monitoring, check that all strings or inputs are configured:

1. On the sidebar at the system level , hover over the system for which you want to set up a string alarm.

2. Open the System configuration for the selected system. 

3. Check that string monitoring is activated by following the steps for string combiner boxes or string inverters:

For string combiner boxes

1. Select the Data sources tab and select Current sensors in the sidebar. Depending on your system setup, you may need to expand several menu items.
   

   

   
   

2. Select the Magnifying glass icon to check the individual strings of each string combiner box.

3. Verify that a check mark is next to each string.
   

   

   
   

For string inverters

1. Select the Data sources tab and navigate to Administration in the sidebar. Depending on your system setup, you may need to expand several menu items.

2. Select the Pencil icon in the String inverter column.
   

   

   
   

3. Check that the toggle is activated for all inverter inputs.