Hotspots And Their Effects On Solar Panels

What is a hotspot on a solar panel?

Hotspots are?areas of high temperature?that affect only one zone of the solar panel and result in a localized decrease in efficiency. The high temperature in the affected area lowers output power and?accelerates material degradation.

?Hotspots occur when solar panels dissipate energy, instead of generating it. The solar cells behave as though they are?consuming energy.

?In addition, hotspots are generally unstable and intensify over time until the overall performance of the panel is eventually nullified.

What causes hotspots?

Hotspots are caused by a multitude of factors and can be classified as either?functional or operational.

?Functional causes can further be divided into two parts:

• Cell mismatch:?which occurs when cells generating different currents are connected in series.
• Damaged or low-quality solar cells: which may occur during manufacturing, as silicon cells are subject to stressful processes during rolling, handling and transportation.

?The operational causes for hotspots are related to the design and operation of the photovoltaic installation, and may include:

• Shadows on solar panels:?If there is a shadow due to low pitch distance between tables on portrait installed modules, panels will suffer systematic shading of the lower row of cells in the morning and night during different seasons. A potential solution would be to install the panels horizontally, which will allow the bypass diodes to be driven at critical times, and ensure the generation of electricity while minimizing formation of hotspots.
• Short Circuit: One or more substring open circuit failure with hotspot. At one or more substrings, easily mistaken for cell breakage or cell defects, Potential induced degradation (PID) or mismatch
• Open Circuit: May be caused by loss of connection within a module junction box or cell connector.
• PID:?The full panel surface is homogeneously heated up compared to other panels. It may happen due to PID effects.
• Partial shading:?May be caused by trees or vegetation.
• Dirt and sand:?Photovoltaic panels can become dirty from dust, suspended sand, dirt and other contaminating impurities during their service life. The maintenance company should identify situations that require cleaning by making periodic visits to the facility. The frequency of cleaning will depend largely on the weather, the conditions and terrain surrounding the park, as well as whether or not the?solar panels have drainage corners.

The effect of sand on the edges, a forgotten problem

In the image below, we see another very clear example of how the?accumulation of dirt affects the cells?located at the corners of the panels. If we look at the image taken by a thermographic camera, we see that many cells in the lower right-hand corners of the panels are at a much higher temperature than the rest, generating a hotspot that, if not solved in time, can end up causing problems.

?NOTE: Choose solar panels with corner drains?to prevent dirt build-up such as the examples below.

Conclusion

As we have seen, the causes of hotspots on photovoltaic panels are varied and in most cases, can be avoided. Choosing a high-quality solar panel with built-in drainage corners, trying to avoid shadows, and having robust O&M practices in place shall reduce hotspots, and ensure the photovoltaic system operates at full capacity.?

Talk to our team to understand more about anomaly detection and the ways in which AI can help reduce their occurrences as well as impact.

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