How worried should I be about the potential solar panel fire?

uge numbers of people are taking the leap into solar power every year. Global PV capacity has already stepped over the mark of one terawatt capacity. But as solar power keeps conquering the global energy market, more and more concerns arise about its safety, and one of these concerns is the risk of fire. Let’s deep dive into the topic to see how dangerous those solar panels are and what we can do about them.

Do solar panels really pose a fire risk?

The short answer is yes. Unfortunately, PV panels can catch fire like any other electrical equipment. And now for the good news: the risk is quite low. As follows from a study of the UK's BRE National Solar Centre, for example, there are about 15 cases of solar panel fire recorded in the country per million installed PV systems. By comparison, as much as 85 toasters and 49 tumble dryers in a million catch on fire.

And yet, awareness of electrical fires is extremely important, as it can help avoid an emergency or even save someone's life. Below we are going to look at the most common causes of solar panel fire.

Causes of solar panel fire

The main source of problems is undoubtedly DC isolators, as they are responsible for an overwhelming majority of solar panel fires.

A DC isolator is a device that plays a huge role in ensuring solar system safety and fire protection. It is a manual switch used to disconnect PV panels from a source of power. This may be needed to stop electricity flow in emergency situations or during maintenance.

The irony is that while DC isolators were designed as a safety tool, they are also a potential source of danger. The isolators can cause a phenomenon called a DC arc fault - the flow of electricity through an ionized air gap. This can lead to solar panel failure as well as start a fire.

DC arc faults are only possible in PV systems with string inverters, which work by collecting DC electricity from PV panels and converting it into alternating current (AC) electricity in one central spot. Microinverters, on the other hand, do not lead to arc-faulting as they are attached to each individual panel and convert DC electricity to AC from each panel separately. PV systems with DC power optimizers are immune to this problem as well because they are able to bring the voltage to a safe level in case of an arc fault.

When it comes to preventing DC arc faults and hence panel fires, the biggest problem is that finding a potential weak point in a solar system can be quite difficult. An average residential installation has over 50 electrical joints in the wiring going from panels to the inverter, and each of them can turn out to be corrupted.

There are several types of DC arcs. A series arc is created when the wire gets damaged while the solar panels keep generating an electric current. That jumps through the air gap in the damaged area.

A parallel arc happens when the current generated by panels starts flowing between the wires of different polarities due to broken insulation. And the last and the most frequent type of fault in solar systems is DC ground fault, which occurs when a conductor carrying DC power from panels comes into contact with an equipment grounding conductor. So in most cases, DC arc faults are caused by loose connection of the electrical joints and degraded or damaged wire insulation.

The fire can also occur due to moisture ingress in a DC isolator. It may happen if conduit tubing and fittings aren’t glued, or cable enclosures are damaged or cracked under intense ultraviolet radiation.

One more problem that may lead to fire is PV panel defects. One of them is so-called hot spots where one cell has an over proportionally higher temperature compared to the neighboring ones. This is a manufacturing flaw caused by poor solder joints, partial de-lamination, or solar cell cracks.

Solar panel facts: Solar panels convert sunlight into electricity through photovoltaic cells. They are eco-friendly, reduce energy bills, and have a lifespan of 25+ years.

Fire safety precautions for solar users

Although there are certain risks involved, they can be minimized by simple but essential safety precautions. Let’s see what can help a homeowner avoid solar panel fire.

High-quality solar system

Even if your budget is limited, purchasing the cheapest PV system is almost never a good idea. You could end up paying for it with your health and safety, as low-price options are likely to malfunction and cause a lot of trouble. Besides, they might even be more expensive in the long run due to constant repairs.

Make sure you buy the best quality you can afford within your allotted budget. You should also pay close attention to the warranty the manufacturer offers. It has to be long-term and have the most expansive coverage possible.

Qualified installers

Choosing the right installer is no less important than choosing the panels. Never hesitate to ask your solar installation company for referrals and testimonials from other customers. You can also ask your neighbors or friends, perhaps they would come up with some recommendations. Online customer reviews can be helpful as well.

Don’t forget to check industry standard licenses and certifications. In the US, PV Installation Professional Board Certification is recognized as the gold standard for solar installers. Another trusted certifier is the North American Board of Certified Energy Practitioners (NABCEP). In some states, their license is compulsory while in others it is not, but it always serves as a quality seal to verify that the company meets industry standards.

Occasional maintenance

If you want to secure yourself against solar panel fire, preventative maintenance is crucial. You can examine your panels on your own from time to time, for example, during scheduled cleaning. If you notice any problems and damages, you should contact your installer to make an appointment with a specialist. And apart from this, their technician has to carry out an inspection at least once per year to make sure they operate properly.

Conclusion

There is no reason to believe solar panels are much more of a hazard than other domestic electrical equipment. In fact, they are inherently safe and pose little to no dander to homeowners. However, you should be aware of any potential problems and take the proper safety measures to further reduce the likelihood of fire.