drone technology in minnesota

Reviewing anomalies

Facebook
Twitter
LinkedIn
WhatsApp
Our full report enables you to review infrared images associated with anomalies identified during site inspection. The IR image shows a higher temperature for the anomalous area or component compared to adjacent areas or components. This is because defects dissipate solar energy as heat rather than converting it to current.

More serious defects have higher temperature differentials. Many manufacturers consider a temperature differential greater than 20 degrees evidence of a defective module, where the hotter module is defective. Anomalies are not always stable and can vary from one day to the next, depending on the conditions at the time of inspection.

Anomalies showing smaller temperature differentials, especially less than 10 degrees, may not require immediate attention but generally continue to degrade over time.

Common causes of anomalies include:

  • Damage during installation
  • Shading
  • Soiling
  • Vegetation
  • Cracking
  • Manufacturing defect
  • Weather events (lightning, hail, wind)
  • Suboptimal grounding
  • Module degradation (for example, delamination)
  • Fuse or connector failure (for strings)


An RGB image can assist in determining the cause of the anomaly. For example, the RGB image confirms vegetation as the cause of this multi cell anomaly:

drone technology in minnesota

The value of a solar inspection is that it provides insight into the impact of anomalies on power production.

Due to solar site design, some anomalies have bigger impact than others. A solar site uses silicon solar cells to convert the energy of sunlight into electricity. The power generated is made available to the grid by means of strings, combiners, and finally inverters, which feed into the point of interconnection.


When assessing anomaly impact on power production, it’s important to consider that outages of components such as combiners and inverters result in a greater reduction in power production than individual cells.

Anomaly Impact (DC)

Little (Watts)

Medium (Kilowatts)

Large (Megawatts)

drone technology in minnesota

Cell

drone technology in minnesota

Diode

drone technology in minnesota

Module

drone technology in minnesota

String

drone technology in minnesota

Combiner

drone technology in minnesota

Inverter

The analytics software uses a power factor to take into account that, for example, a string outage will have much greater impact on overall power production than a cell outage.

For more information, refer to Calculating impact of anomalies and power factors.

Our analysis report is provided by Raptor Maps and checks for all of the following anomalies:

We identify about 36 different anomalies over a solar asset

A ballast consists of concrete blocks used to secure an array of solar modules to the ground or the roof. A ballast anomaly indicates a broken ballast.

Hot spot occurring with square geometry in single cell.

Cell anomaly, where the temperature of an anomalous area is less than 10˚C higher than adjacent areas.

Cell anomaly, where the temperature of an anomalous area is 10-20˚C higher than adjacent areas.

Cell anomaly, where the temperature of an anomalous area is 20˚C higher than adjacent areas.

Hot spots occurring with square geometry in multiple cells.

Cell multi anomaly, where the temperature of an anomalous area is less than 10˚C higher than adjacent areas.

Cell multi anomaly, where the temperature of an anomalous area is 10-20˚C higher than adjacent areas.

Cell multi anomaly, where the temperature of an anomalous area is 20˚C higher than adjacent areas.

A combiner combines many strings into a larger flow of DC (direct current). A combiner anomaly shows fault in contiguous strings matching the inverter layout.

Module anomaly caused by cracking on module surface.

Module anomaly due to compromised adhesion between glass, encapsulant, active layers, and/or back layers. More common with thin film modules.

A bypass diode provides a current path around a faulty cell or module. A diode anomaly indicates as activated bypass diode, typically 1/3 of module.

Multiple activated bypass diodes, typically affecting ⅔ of module.

Anomalous spot on a cell.

Hot spot, where the temperature of the anomalous area is less than 10˚C higher than adjacent areas.

Hot spot, where the temperature of the anomalous area is 10-20˚C higher than adjacent areas.

Hot spot, where the temperature of the anomalous area is 20˚C higher than adjacent areas.

Multiple hot spots on a thin film module.

Hot spot multi, where the temperature of the anomalous area is less than 10˚C higher than adjacent areas.

Hot spot multi, where the temperature of the anomalous area is 10-20˚C higher than adjacent areas.

Hot spot multi, where the temperature of the anomalous area is 20˚C higher than adjacent areas.

Multiple cell anomalies as a result of a short circuit.

An inverter converts the DC current of many combiners into usable AC. An inverter anomaly shows fault in contiguous strings matching the inverter layout.

A junction box is an enclosure on the module which connects the PV strings. A junction box anomaly is a hot spot at the junction box location on the module.

Junction box anomaly, where the temperature of the anomalous area is less than 10˚C higher than adjacent areas.

Junction box anomaly, where the temperature of the anomalous area is 10-20˚C higher than adjacent areas.

Junction box anomaly, where the temperature of the anomalous area is 20˚C higher than adjacent areas.

Module is present on as-built but missing from PV system.

Entire module is heated.

Sunlight obstructed by vegetation, man-made structures, or adjacent rows.

Dirt, dust, or other debris on surface of module.

Module is present on as-built and marked as offline.

A string consists of an individual set of modules connected in series. A string anomaly shows fault in contiguous modules matching the string layout.

Tilt tracker position affecting power production.

Modules blocked by vegetation.

Related Posts:

drone technology in minnesota
Aerial Thermography

Inspection to support warranty claims

Hot spots and activated bypass diodes are indicators of potential module failures. If the modules are within warranty, you can use evidence of these types of failures to support a warranty claim. Simply Drones assists you to identify these issues, as well as provides the documentation necessary for a claim.

Read More »