What are Hot Spots and how they affect Solar Panels

Hot spots in solar panels are areas on the panel that are subject to higher temperatures than the rest of the panel. They are a common occurrence and are hard to predict. Cell the pressures can usually go up to 150° C which leads to permanent and irreversible damage like glass cracking, cell degradation etc. When solar cells are connected in series and when one cell is shaded this reduces the overall current in the strings of solar cells connected, causing the good cells to produce higher voltages that can often reverse bias the bad cell.

The operating current of the overall series string approaches the short-circuit current of the bad cell. If the series string becomes short short-circuited forward biased of the solar cells will reverse bias of the shaded cell. The entire power power-generating is dissipated in the shaded cell. The enormous power dissipation occurring in a small area result in local overheating. this can lead to a decrease in the efficiency of the panel and a reduction in the amount of energy it produces. In severe cases, hot spots can cause permanent damage to the panel, reducing its lifespan and making it less cost-effective over time. Figure below shows a series of solar panels connected together and the right most panel is partially shaded
The primary cause of hot spots in solar panels is shading. When a portion of the panel is shaded, a large number of series connected cells cause a large reverse bias across the shaded cell. This can cause a build-up of heat in the affected area, leading to an increase in temperature and the formation of a hot spot. Additionally, shading can cause a reduction in the overall efficiency of the panel, as the cells in the shaded area are not able to produce electricity at the same rate as the rest of the panel. Another factor that contributes to hot spots is dust and debris build-up. Dirt and dust on the surface of the panel can block some of the sunlight that would normally reach the cells, leading to a reduction in performance and an increase in temperature. Additionally, debris can interfere with the flow of air over the panel, which is crucial for dissipating heat and maintaining a consistent temperature. The design and construction of the panel can also play a role in the formation of hot spots. Poor insulation or inadequate ventilation can lead to overheating and hot spots, as heat is not able to dissipate effectively. In some cases, the cells themselves may be poorly designed or manufactured, leading to reduced performance and increased heat generation.

Impact of hot spots

The impact of hot spots on the power generating capacity of solar panels can be significant. In addition to reducing overall performance, hot spots can cause permanent damage to the cells, reducing the power output of the panel over its lifetime. This can make the panel less cost-effective in the long run, as the cost of repairs and replacement may outweigh the savings generated by the panel.

How to prevent hot spots

To prevent emergence of hot spots, the different causes have to be considered. To mitigate the impact of hot spots, it is important to regularly clean the panels and ensure that they are free of shading and debris. Additionally, proper insulation and ventilation can help to dissipate heat and prevent overheating. One way to ensure the solar panel is not completely affected is by using bypass diodes. Bypass diodes are an important component in solar panels. They are electrical devices used to ensure that the performance of a solar panel is not affected by shading or a fault in a single cell.

Figure above shoes the bypass diodes connected to solar cells. Currently the majority of modules use three diodes for 60 or 72 cells, or one diode for every 20 or 24 cells. A bypass diode is connected in parallel with individual cells within the panel, and acts as a bypass or a shortcut for the current generated by the cells. If a cell is shaded, the diode prevents the current from flowing through that cell, directing it instead through the diode, ensuring that the rest of the panel continues to generate electricity. Similarly, if a cell is damaged, the diode can help to prevent the damaged cell from negatively affecting the performance of the rest of the panel. Bypass diodes are typically rated to handle a specific current and voltage, and are chosen based on the specifications of the solar panel in which they are being used. They are usually mounted on the back of the panel and are designed to be as compact and low profile as possible, so as not to affect the aesthetics of the panel. Finally, selecting panels that are designed and manufactured with high-quality materials and with a focus on performance can help to reduce the likelihood of hot spots.


AE Solar Hot spot free PV modules

Ae Solar’s engineering teams are always focused on new innovations and emerging technologies in photovoltaic. Their continuous effort and research allows AE Solar to deliver its products with high quality & reliability.
As a result of our R&D activities, we’ve successfully developed the world’s first Smart Hotspot Free module for mass production with TÜV certification in 2016.
We use bypass diodes between each cell in our Hot-Spot Free Modules to eliminate the development of hot-spots and thus the damages and risks associated.
Available up to 350Wp range, the AE Smart Hot-Spot Free Modules offer up to 30% more power output compared to standard PV Modules thanks to their improved efficiency. This added efficiency translates into less modules needed and less space required for installation.


In conclusion, hot spots are a common issue that can significantly impact the power generating capacity of solar panels. By understanding the causes of hot spots and taking steps to mitigate their impact, it is possible to maximize the efficiency and performance of solar panels and ensure that they remain a cost-effective and sustainable source of energy.

Authors: Vidhyashankar Venkatachalaperumal, Afshin Bkahtiari

Leave a Reply