Keep fire safety front of mind in commercial solar installations

By John Hostetter, senior director of product management at REC Solar

Stories about fires caused by faulty solar installations tend to make the news because solar energy is still relatively novel. “Electrical fire” isn’t as interesting as “solar fire” might be. But there is no evidence that fires caused by solar energy systems are any more common than ones caused by traditional electrical systems. And when fires do happen, the cause is often the same as any other kind of electrical fire: old, worn-out components, power surges, wind or lightning, bad design or faulty installation.

Innovations in design and installation techniques in recent years have greatly reduced the risk, but that doesn’t mean there’s no risk at all. Oftentimes, that risk comes down to human error. Systems that are installed poorly are going to cause problems.

The best way to prevent such an accident is to choose a certified installation firm, perhaps one recommended by the manufacturer. Of course, the manufacturer must be one that pays heed to quality control, and one that insists on using components that pass muster in terms of safety, durability and reliability.

One of the biggest mistakes a buyer can make is to sacrifice quality for up-front cost-savings. That is, going cheap. Even aside from the safety considerations, buying a cheap system will cost more money in the long run due to the need for maintenance and repair. Such systems also tend to be less efficient, which increases power costs. Some of the better manufacturers and installers will offer an inspection program to make sure there are no broken or loose wires or other components. Otherwise, it is a good idea to hire an experienced O&M firm to handle this task.

Even with the best of systems and the most careful inspection regimes, however, fires can happen. So it pays to be prepared for such an eventuality.

Rooftop solar poses a potential problem just by virtue of its placement: on the roof, where it’s exposed to the elements, and where, when fires do break out, the potential for disaster is far higher. Of course, this isn’t really anything new, as electrical systems have been on roofs for a long time. Again, there are some special considerations with solar. One thing to look out for is whether the panels have individual DC-to-AC converters. Many newer systems have these, and they are much safer.

All these things are true no matter what kind of power system you install. Still, there are special considerations to prevent fires involving solar installations and ways to deal with them when they occur.

The cause of fires in solar systems is often a problem with DC/AC inverters. Another relatively rare cause is a voltage fluctuation that can sometimes occur when excess electricity from a system is sent to the grid.

On large commercial rooftop systems, DC arcs can sometimes happen. That’s when a disconnection in a live wire sends electricity into the air, and anything flammable nearby can catch fire. While arcs can happen with any electrical system (or even a bedside alarm clock), photovoltaic systems are more vulnerable because they send high-voltage, high-amperage, DC current back to the grid. Such arcs can’t self-extinguish and they often reach very high temperatures.

Though much progress has been made on the design of solar-energy systems, some of the components, such as the backing on PV cells, can sometimes still be more combustible than components found in traditional power systems.

One perhaps surprising area of hazard lies in the way solar cells react to shade. When the sun moves off a cell, it starts to act as a resistor, turning energy into heat as the current from other cells moves through them–just as resistors do in any electrical system. This was a bigger problem in older systems that has been largely solved with the inclusion of voltage-resistant diodes that bypass the shaded cells. It’s still something to keep in mind, though, especially during installation. If in doubt, it’s best to ask the manufacturer or installer.

Thanks to the fact that solar-energy systems are powered by a source that can’t be shut off (the sun), disconnecting solar installations is often much more difficult than merely throwing a circuit breaker. Newer systems are generally designed to be easier to shut down in the event of fire, but it’s still something to consider when choosing a system.

Also, before installing, make sure to have the roof itself inspected. Even the best solar-energy system installed on a leaky or rotting roof will pose a major risk. In terms of installation, make sure that there is plenty of space between panels to give firefighters plenty of access. This is especially important for larger commercial systems.

Finally, it is a good idea to inquire with your local fire department to make sure firefighters have specific training in dousing conflagrations involving solar-energy systems. Most departments in big cities now do this as a matter of routine, but there are areas–particularly in regions that haven’t taken to solar in a big way yet–where fire departments offer no such training at all.

The most important benefit of using solar panels is that solar energy is a truly renewable energy source. Building owners are choosing to combat greenhouse gas emissions and reduce their collective dependence on fossil fuel. Ensuring the safety of a commercial building when using solar panels is just like any other source that needs maintenance and care.

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