Quality

Enemies of photovoltaics - the Hotspot

The present and future hold great challenges for photovoltaic technology in terms of material quality, installation, operation and, finally, decommissioning. Photovoltaic technology is mature, but only if the industry responds adequately to the demands for secure and reliable supply can it establish itself as a major source of large-scale electricity.

HotSpot

In this installment we will go deeper into a serious defect that can be found in photovoltaic modules due to poor quality materials and/or handling: the Hotspot. 

What is a Hotspot? 

A hotspot is an area within the PV module that becomes excessively hot and can lead to its destruction or even to a fire. 

How does a Hotspot originate? 

Hotspot occurs due to high resistance in a specific area of the PV module. The affected area becomes a consumer of electricity that generates heat, even exceeding 200ºC. 

Resistance is caused by internal defects or shading from the environment. Shading can be occasional (dirt, droppings...) or constant (trees, chimneys or other elements that cast temporary shadows on the generator). 

Here are some examples: 

Broken weld: The use of an inadequate jointing paste for interconnectors or poor soldering processes can lead to breakage of the interconnectors. It can also occur during transport or handling of the module on site. 

Interconnection of broken cells 

 

Hotspot
HotSpot
HotSpot

Hotspot generation process: Incendiary chain 

The aforementioned defects lead to irreversible processes which, depending on the duration of the effect, can range from loss of performance to destruction of the module or even fire. 

 

HotSpot
HotSpot

Possible electric arc, permanence of the flame after the electric arc is extinguished in the surrounding material 

Fire in a photovoltaic plant 

How do you avoid a Hotspot? 

A Hotspot is a defect that can appear at any time during the life of the module; it can be induced due to poor manufacturing of the module. On the other hand, if transport and handling during installation are inadequate, the chances of hotspots appearing during the lifetime of the installation increase. 

The following are recommendations to avoid Hotspots: 

  • Buy material from well-known and proven brands, with certified and transparent manufacturing processes. 

  • Ensure transport to the site with maximum precautions. The modules are delicate equipment and must be palletized with no weight on top, to mention two basic transport conditions. 

  • When installing the material, make sure that the modules are not stepped on and follow the manufacturer's installation instructions. 

  • Clean the modules, as required by the circumstances of the site installation. For example: in a place with little rainfall and modules installed with little inclination, the modules should be cleaned more frequently. This is not only to increase the plant's performance, but also to avoid the appearance of Hotspots. 

  • Regularly check the plant. In addition to constant monitoring of the plant, a visual inspection with special measuring equipment should be carried out at least once a year. 

With all these measures in place, Hotspots and many more defects can be effectively combated. The cost of repairing defects grows exponentially the later they are discovered, so every penny invested in quality of materials, installation and revisions ensures an economic benefit.