The average annual temperature, for the vast majority of our country is above 30 degrees Celsius.
Solar panels, also commonly referred to as solar modules, are installed in the open and operate at 15-20 degrees Celsius higher than the ambient temperature.
This means that the solar panels are operating at temperatures above 45 degrees Celsius regardless of the season. Though this temperature varies throughout the day, they are fairly equal through out the panel.
However certain factors can cause small, specific parts of the solar panels, to heat up to
temperatures that are much higher than the rest of the panel!
These localized areas giving out intense heat are referred to as 'Hot Spots'. They cause irreversible damage, degradation, and loss in output.
Hot spots are caused either due to Internal Factors or External Factors
Internal Factors include: Poor quality of solder bonds, use of substandard components, defective diodes, micro-cracks in cells, etc.
External Factors include: Shadows, soiling, bird droppings, sitting/ standing on the panel during installation, damage during transportation, etc.
To know more about the damage that shading causes click here.
How to safeguard against Hot Spots:
Choose the right solar panel manufacturer
Choose the right solar panel/ system installer
Choose the right solar panel manufacturer
Solar panel manufacturers have to account for several factors to ensure the prevention of the formation of hot spots.
Every component should be of the highest quality and every process strictly adhered to.
Here are some key steps that are necessary to avoid the formation of hot spots while manufacturing a panel.
Ensuring that the required 'creepage' and 'clearance' distances are maintained according to applicable standards while designing and manufacturing the panels.
Using high-quality Encapsulant material that creates a cushion and protective covering on both sides of the PV cell to prevent the formation of micro-cracks because of external/ internal stress on the module.
Quality, automated soldering to prevent breakage of solder bonds. When the power produced by the PV cell cannot be transported due to faulty or broken solder bonds the energy is released as heat into the environment.
A robust Backsheet, comprising of quality raw materials and a high melting point (≥ 250 deg C) can help temporarily moderate the effect of the hot spot and maintain the insulation requirements for safety.
Consistent lamination of the panel is crucial to protecting the delicate solar cells. It prevents the formation of air bubbles, cell breakage and de-lamination of the solar panel after installation.
100% EL imaging (electro-luminescence) before and after lamination. EL imaging allows the panel manufacturer to quickly check for defects in the cells, stringing, and presence of micro-cracks if any. (See how modules are manufactured here.)
Ensuring that the module manufacturer is using Electrostatic Devices for the Junction Box assembly to prevent damage to the diodes. Bypass diodes help reduce the damage of hot spots caused due to shade. However, if the bypass diode is itself defective, the hot spot temperature could go beyond 200 degrees C, resulting in permanent damage to the panel.
Choose the right solar panel/ system install
Ask your prospective installation partner about how they choose solar panels for a project, both the type of panel and the manufacturer.
Visit/ review reference projects.
Make the time to understand how a solar installer will help address your specific requirements before making a choice.
For example: Standalone homes have ample rooftop space, but the roof itself may not be easily accessible. Hence you will need to discuss both installation and maintenance that includes frequent cleaning of the panels with your installer.
Solar panels are built to last 25 years.
Keeping track of your solar systems' output and performance is an effective way to ensure a quick response to any changes that may be detrimental to your investment!
It could be something simple like trimming a few branches or something that requires a little help like cleaning your panels.
The only corrective action if one or more solar panels have a hot spot is to replace them before further damage is caused, both to the panel and to the entire system.
Hot spots reduce output and may be a serious safety issue, but with the right panel and installation partner, they are avoidable...