This blog will explain some of the factors that can lead to fires in solar generation of equipment, particularly older systems. But first, if you’re concerned about your own solar system, your best move is to call an experienced operations and maintenance (O&M) service provider to inspect and verify your installation. Simple steps, such as scanning your equipment with and infrared camera, can identify hot spots that, left unattended, could lead to combustion. Once found, these developing problems can always be remedied at a far lower cost than system and structure repairs after an avoidable fire.
Where are these hotspots found? One of the weaknesses in older solar installations is the junction box. This is where current from multiple panels comes together to be fed to the main power collector. In older systems, these junction boxes were sometimes under-engineered, potentially resulting in a fault, leading to a hot spot and eventually a fire that could spread to the rooftop and the underlying structure. Modern junction boxes avoid this problem through robust engineering with ample current-carrying capacity. As a result, this issue occurs today only in older systems or systems using inferior components from second- and third-tier suppliers. Similarly, older solar modules were manufactured using processes that were less robust and not as refined as modern techniques. That’s a natural part of any new product development curve, but in solar modules it gave rise to the possibility of poor connections and even metal shards inadvertently built into the panels. These defects in manufacturing were another potential heat source that could result in combustion. Today, years of experience has shown manufacturers how to avoid these flaws. Other product improvements include listed and tested outdoor-rated connectors built into the modules to assure solid connections with external cabling and other equipment.
Additional issues results from the way solar cells react when they fall into shade. Shaded cells tend to work as resistors, transforming energy collected by illuminated cells into heat as current flows through them. Once this problem was identified, engineers improved the protection of individual cells by installing high voltage diodes that bypass these resistive elements, ensuring better current flow. This module architecture, combined with new techniques such as improved mounting adhesives, potting materials, and other manufacturing and material improvements result in safer and higher production modules. With this protection in place, modern solar collector panels are far less likely to overheat.
The third-largest contributor is substandard installation. Some designers and installers have been known to forget to account for heating and cooling of electrical conduits and other hardware, so they didn’t accommodate expansion and contraction of these elements. Unfortunately, when a conduit expands, and that expansion is not accounted for properly, the expansion may stress the electrical wiring inside of it, potentially causing electrical connections to loosen and come apart. When this happens energy arcing across the open connection can also result in heat and a risk of fire. Higher quality installers and designers note to engineer electrical runs with adequate slack to avoid problems such as this.
Moving away from the rooftop, the point where energy from solar collectors feed into the building’s electrical system has been a source of concern in the past. Under-engineered combiner boxes pose the same hazard as their rooftop counterparts causing heat buildup and sometimes sparking fire in the utility room. Additionally, older AC-to-DC inverter systems lacked the capabilities of modern ground fault detection systems, sometimes allowing short circuits to go unnoticed again resulting in sparks and fire. Today’s more-sophisticated inverters provide improved and more comprehensive and regular sensor readouts that allow operators to spot and avoid problems like developing ground faults before they pose a hazard.
This is not to say that today’s solar panels are absolutely without fault. Quality engineering, production, and installation provide a kind of “defense in depth” where faults are far less likely. But like even an upscale automobile, problems can exist or emerge over time. An assembler can have a bad day, a manufacturer can have a bad run, and an engineer can overlook a detail. Unlike the days when cars shipped to dealers were expected to contain defects, it’s now far less likely that the product you receive will possess manufacturing shortcomings. Although even one flaw is frustrating to the buyer who receives it, your odds of being that unlucky buyer are smaller today.
This overall improvement throughout the value chain from manufacturing to deployment has resulted in far safer solar electric generation installations with far lower chances of fire. But just as with that luxury car, regular maintenance is still necessary to keep your purchase performing at its peak potential. Engaging a qualified and experienced operations and maintenance service provider is essential to ensuring ongoing system health and detecting problems that may develop overtime. Owners must never forget that a solar collection system is a high-power electrical installation exposed to the weather on their rooftops. But with regular upkeep, testing, and quality assurance, it will remain as safe and reliable as any other appliance in their facility.
So, what’s the takeaway? As with anything else, you get the quality you pay for when you adopt solar electric generation systems. It’s better to pay a little bit more during design, purchasing, and installation than to work with designers of lesser skill, installers with lesser experience, and equipment with lesser reliability. In this way, solar equipment is no different from any other electrical hardware: maintain it well and it will provide many years of safe service, but skimp on support, and you risk the same hazard as deferred maintenance presents on any high-power installation.