Thermal Anomaly Properties

In this article you will learn the different properties assigned to each thermal anomaly found on your solar site.

Updated over a week ago


With a Solar Thermography operation from Sitemark, you will get an overview of all thermal anomalies present on your solar site. Each thermal anomaly will have a detailed list of properties, including anomaly type, anomaly cause, delta temperature, remedial action, and much more.

Having detailed information on each thermal anomaly will help you to get better insights on your solar site condition.

What are the Anomaly Properties?

You open the list of properties for each thermal anomaly by clicking one of the thermal anomalies on the 2D map view, as shown in the following print screen.

screenshot of anomaly property

Anomaly Type

Sitemark identifies the type of the thermal anomaly. For more information about the different types, please go through this article.

Anomaly Cause

Sitemark identifies the thermal cause of the anomaly. Understanding the cause of the anomaly within your solar site will drastically improve your ability to maintain and run an efficient solar park.

Once you understand where and what is causing problems, it's much easier to take remedial action. For more information about these cause classifications, please go through this article.


All anomalies detected are automatically classified into different severity levels. The severity evaluation helps in prioritising which anomalies to focus on. Sitemark defines 3 severity levels:

  • Mild - These are issues that require no immediate action, yet are essential to monitor over time.

    • Hot spot 0-5 °C DeltaT

    • Multi Hot spot 0-2,5 °C DeltaT

    • PID

    • Suspected PID

    • Junction Box

  • Serious - These are solar panels that show issues and are recommended to be replaced during the next maintenance cycle.

    • Hot Spot 5-15 °C DeltaT

    • Multi Hot Spot 2,5-7,5 °C DeltaT

    • Single Bypassed Substring

  • Critical - These are solar panels generating significant loss and are recommended to be acted on as soon as possible.

    • Hot Spot 15+ °C DeltaT

    • Multi Hot Spot 7,5+ °C DeltaT

    • Double Bypassed Substring

    • Open Panel

    • Open String

    • Missing Panel

    • Diode issues

Estimated Loss

Sitemark developed a loss estimation model that gives an indication of the energy yield loss. The loss estimation figure in % helps you to quantify the underperformance of your solar site. The loss estimation for a panel is calculated as follows:

Loss estimation = (% Panel loss * Panel Maximum Power) * Photovoltaic power potential

Keep in mind that the following site properties must be filled out in order to get an estimated loss calculated:

  • Feed-in tariff

  • Photovoltaic power potential (PVOUT)

  • Panel Maximum Power (Pmax)

Remedial Action

All anomalies detected are automatically analysed by Sitemark and are assigned to a specific remedial action. Sitemark uses the following remedial actions:

  • Quick fix: An easy fix which should typically not take more than 10min of work.

  • Repair: A repair that will take more than 10min of work.

  • Move: Move the panel to another location or string or change the wiring. For example, this might be the case when shadowing is causing the anomaly.

  • Clean: Clean the solar module. For example, this might be the case when dropping or soiling is causing the anomaly.

  • Remove vegetation: Remove the vegetation around the the solar module.

  • Warranty: When the solar module is still in its warranty period, you can add this module to the warranty claim towards the manufacturer.

  • Replace: Replace the solar module.

  • Monitor: Monitor this solar module during any new inspection.

  • Field Check: Let the technician on site take a closer look at this problem.

  • Do Nothing: This is a temporary problem that is expected to cure over time.

Remedial Cost

The cost to execute the remedial action. This property is calculated using the site properties and the remedial action. The unit is the selected currency.

Estimated Loss / Year

The financial loss over a period of 1 year. This property is calculated using the site properties, like we do with the loss estimation in the Statistics Mode. The unit is the selected currency.

Remedial Payback Period

The total period to earn back the remedial cost by taking into account the increase in energy yield. The unit is months.

Max Temperature

The maximum temperature in the solar module. The unit is degrees Celsius.

Delta Temperature

The difference between the maximum and the average temperature in the solar module. The unit is degrees Celsius.

Normalised Delta Temperature

The delta temperature based on the irradiance to the Standard Test Conditions of 1000 W/m². The unit is degrees Celsius.

This is a calculated property and it is only available when the Global Tilted Irradiance (GTI) was uploaded in the weather data.

Normalized Delta Temperature = 1000/GTI * Delta Temperature

Mean Temperature

The average temperature in the solar module. The unit is degrees Celsius.


The geographic coordinate that specifies the east–west position of the solar module. The unit is decimal degrees.


The geographic coordinate that specifies the north–south position of the solar module. The unit is decimal degrees.

Zone - Row - Blocks

The associated region in which the solar module is located. You can define the regions yourself in the Region Manager on Sitemark Fuse. For more info on how to create or edit regions on your solar site, please check this article.

Weather (beta)

If weather data was uploaded from a handheld device or pyranometer, it will be used to add weather properties in the thermal anomalies. Sitemark Fuse will use the time stamp to extract the weather details from the imported weather dataset. If the user does not upload any weather dataset, the weather properties won't be included in the anomaly properties.

Global Tilted Irradiance

(GTI) The irradiance the solar module was receiving in its exact orientation and tilt. The unit is W/m².

Wind Speed

The speed of air in the environment surrounding the solar modules. The unit is m/s.

Wind Direction

The direction where the wind is coming from. The worldwide convention is that wind coming from North is 0°, East is 90°, South is 180°, West is 270°. The unit is degrees (°).

Air Temperature

The temperature of the air surrounding the solar modules and is typically measured in degrees Celsius (°C) or degrees Fahrenheit (°F).

Relative Humidity

The ratio of the current absolute humidity to the highest possible absolute humidity, which depends on the current air temperature. 100% of relative humidity means that the air is saturated with moisture. The unit is %.

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