Reviewing Solar Energy Anomalies
The Raptor Maps application enables you to review infrared images associated with anomalies identified during a 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:
- Installation damage
- Local shading
- Panel soiling
- Nearby vegetation
- Panel cracking
- Manufacturing defects
- Weather events (lightning, hail or 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:
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 impacts 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 impacts 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 anomalies of individual cells.
Anomaly Impact DC
Raptor Maps 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 this page on Calculating Impact from anomalies.
Raptor Maps analysis checks for all of the following anomalies:
Anomaly
Description
A combiner combines many strings into a larger flow of DC (direct current).
A combiner anomaly shows a fault in contiguous strings matching the combiner layout.
A bypass diode provides a current path around a faulty cell or module.
A diode anomaly indicates an activated bypass diode, typically 1/3 of the module.
An inverter converts the DC current of many combiners into usable AC.
An inverter anomaly shows a fault in contiguous strings matching the inverter layout.
A junction box is an enclosure on the module that connects the PV strings.
A junction-box anomaly is a hot spot at the junction-box location on the module.
A string consists of an individual set of modules connected in series.
A string anomaly shows a fault in contiguous modules matching the string layout.