Solar fires are rare but can lead to devastating damage to buildings and materials. Though PV system fires are infrequent, improper installation and overlooked maintenance can cause serious issues, eventually leading to electrical fires on the roof or at the inverter.
In recent months, FutrOS has conducted thorough fire inspections on several commercial solar installations, identifying the main causes as water ingress and insecure connections at rooftop isolators. Fortunately, in all cases, extensive damage was avoided due to prompt action from onsite personnel and emergency services.
Given the significant risk fires in PV systems pose to the safety and reputation of the solar industry, it is crucial to understand the causes of solar PV fires and how to prevent them effectively.
Our inspectors and engineers have examined over 10,000 grid-connected solar PV systems (all within the past 10 years). Throughout this time, we have determined that there are three main reasons why these fires are caused.
Cause 1: Entry of water into DC isolators
The DC isolators (especially the DC isolators located on the roof) are considered the common cause of fires in PV systems. Traditionally, rooftop isolators have been an obligatory requirement in India to permit the fire safety services along with other workers to detach the system at the assortment- i.e. while on the roof. Nonetheless, when the rooftop isolators are more exposed to the elements, they tend to be a lot more susceptible to deterioration. Moreover, they tend to be less apparent that leads to a time lag situation: the issues occurring at the rooftop isolator are often missed until it’s too late. Although contemporary regulatory modifications now allow alternatives to the rooftop isolators, there still are numerous rooftop isolators already installed.
Improper installation methods to sustain the ingress protection (IP) of the isolator enclosures can cause the water to get in and gather inside the isolator enclosure hence triggering corrosion of the terminals. Especially when it comes to the inundated isolators, it tends to damage the internal elements of the isolator too. When the isolator transmits current in such a state, higher resistance at the areas where corrosions took place, causes a hot joint which ultimately directs to fire.
Common water entry points in the DC isolators include:
1. When the conduit isn’t glued water seeps in gradually at the connection point or allows maneuver which later causes the conduit to fall out, creating a permeation point. Conduit entries include caps for the unused entries, all being glued together.
2. The screw not being secured or sealed can allow the water to slowly enter inside from the other side of the screw.
3. Incorrect cable glands worn, i.e. it should be ensured that multi-hole glands instead of the single whole compression glands are used to adjust the cables accessing the conduits. Any extra holes that aren’t used must be plugged up.
4. Inappropriate ingression of the enclosures such as drilling holes in an enclosure without securing them can cause the water to exude. Penetrations made anywhere apart from the lower surface tend to have a higher leakage probability, thus allowing water to drop onto other components
5. Excessively tightened screws that lead to loosened screws or ruptured enclosures result in an inadequate seal. Each case involves not adhering to the manufacturers’ torque setting, thus allowing the water to leak. Expectantly, there is going to be a decline of the water ingress with AS/NZS 5003:2021 Clause 4.4.7 outlines installation prerequisites for rooftop isolators in specific cases. It tends to outline that these installations prevent the water from leaking any further.
Cause 2: Cable termination
Terminals as well as the connections need to be properly tightened so that the current can flow through properly. When torque settings are not pursued or connections are loose, it results in the creation of hot joints. This heat that is produced can later melt the plastic around the cause and cause fire.
Thus, mindful attention should be given to the location and length of these cables in the enclosure to avoid damaging the cables.
Cause 3: Module Damage
The solar modules tend to get tested in such a way that it can be ensured that they can withstand various conditions. However, any damage to the module can result in internal cracks aka microcracks that can not be spotted easily, which can lead to fires. These cracks/ microcracks can be caused by various things such as earthing lugs mounted against the back sheet that cause abrasion, smashed modules, and people walking on these modules i.e. improper transport. These modules can also get damaged by the delamination of their back sheet as it causes the water to seep in causing potential short-circuits to occur. Though it doesn’t cause fires it does reduce the overall system output and make the roof hazardous.
Prevention
Solar fires are usually caused by errors and oversights. The most common error is how risk exists because proper care is not taken during the installation period when it comes to ensuring that the water is kept out, this usually causes the fire to start when the issue is not picked up early. Moreover, gradually the severity of these fires can increase if leaf litter is allowed to build in e.g. the rooftop isolator being installed close to the flammable materials.
Be it a lack of motivation or knowledge, if the issue is not addressed on time dangerous situations can be brought about. These solar fires are, however, avoidable. It should be ensured that the performance of the solar system is occasionally checked, and that ingress protection is maintained. Thus, ensuring that the connections are still tight.
Prevention Tips for Solar PV Fires
Solar fire prevention is primarily about adhering to best practices during installation and maintenance:
- Use Reliable Products: Ensure the use of products with reliable warranties, reducing the likelihood of failure.
- Choose Trusted Installers: Select installers who have a proven track record to minimize installation errors.
- Regular Inspections: Inspect the system regularly—once a year after installation, and every five years thereafter.
- Clean the Area: Remove leaves and debris around and under the array to prevent fire spread.
- Avoid Combustible Materials: Keep flammable materials away from rooftop PV systems.
- Utilize Asset Management Tools: Use tools like FutrOS ‘Diagno’ for early detection of issues and solar fire risk management.
Contact FutrOS today for more information on how Diagno can help keep your property safe from the risk of devastating solar fires.
FAQS:
What are the common causes of solar PV fires?
The primary causes include water ingress into DC isolators, loose cable terminations, and damaged solar modules.
How can I prevent fires in my solar PV system?
Use reliable products, choose trusted installers, conduct regular inspections, keep the area clean, avoid flammable materials, and use asset management tools like FutrOS ‘Diagno’.
Why are DC isolators a major cause of solar fires?
DC isolators, especially on rooftops, are prone to water ingress, causing corrosion and increasing resistance, which can lead to hot joints and fires.
What is the role of regular inspections in preventing solar fires?
Regular inspections help identify potential issues early, such as loose connections or module damage, preventing escalation into severe problems.
How can FutrOS Diagno assist in solar fire prevention?
FutrOS Diagno offers advanced monitoring and inspection tools to detect issues early, enabling timely interventions to prevent solar PV fires.
