Last week’s solar fire in Forest Park has brought to the public’s attention the question of the safety of solar PV systems.
“Is solar really safe? Why would solar panels catch on fire? Is this covered by the insurance and who is paying for the damage?” were some of the questions asked by many. The answer to the first question is a yes; solar PV systems are very safe. According to Energy.gov a study has been done in Germany which found that out of 1.7 million systems installed there only 210 caused fires, which amounts to 0.012%. Although these cases are exceedingly rare, it is important to realize that a solar PV system is an electrical device, and, as such, has a potential to cause fire, especially if not installed properly or if the appropriate safety measures are not taken.
Thanks to the generous Government incentives, solar has become increasingly common in our community; therefore, I find it worthwhile to present a few tips which can help make it both safe and profitable.
The first and arguably the most important solar safety tip is to protect the panels from squirrels. The bushy tailed rodents love to make nests under solar panels, and to chew on wires, causing severe damage to the insulation, connectors, and, in some cases, even to the copper conductors. This is extremely common; in my experience, the vast majority of solar arrays that have been exposed to squirrels for a significant amount of time have damaged wiring. The accepted way to prevent this is by installing a steel “critter guard” net around the panels. The “critter guard” must be installed any time that there are tree branches within six feet of any part of the roof. Alas, a mere drive around town will reveal many solar installations in wooded areas without any squirrel protection; and the system that burned in Forest Park last week was one of them. Fortunately, modern inverters are designed to detect the ground faults and the arc faults, which result from the damaged insulation, and will shut down if such conditions are found. This important safety feature greatly reduces the risk of solar panel fires, but it comes at the cost of lost production – the system will not operate until the fault is repaired. Furthermore, in some cases, the arc fault can happen, and possibly cause a fire, before the inverter has a chance to shut down.
Loose electrical connections can also cause arcing and electrical fires. This problem is harder to detect than the exposure to squirrels, and there is no way for a homeowner to ensure that all electrical connections are secure. My best advice to a homeowner is to choose a reputable installer. A quality minded installer will design the system so as to minimize the number of connections and other potential points of failure; use reliable equipment; and train the workers to routinely double check every electrical connection.
Another important tip for the prospective solar buyers is to avoid installing solar on old roofs. This mistake, while not affecting the safety of the system, can greatly reduce its profitability. The life expectancy of a solar PV system is about 25 years. This is close to the life expectancy of a roof, thus if both are installed around the same time, both will need to be replaced at the same time, as well. If, however, the roof is old, and will need to be replaced a few years after the solar installation, the very significant cost of removal and reinstallation of the solar panels will have to be added to the cost of the new roof. The life time of the new roof might be shortened, too, because if the solar is replaced at the end of its life, the roof will have to be replaced, as well.
The moral of the story is not to discourage solar. Solar is profitable; a typical residential system pays for itself in mere five years. It is also safe, especially when protected from squirrels. At the same time, not all solar PV systems are created equal, and when considering solar proposals one must be mindful of more than just the price.
Submitted by Shlomo Lagoviyer, Green Revolution Solar
Please feel free to call me with any questions @ 848.285.4853.