Panels Turned Off? They Can Still Bite…!

Photovoltaic Devices…better known as“Solar Panels”, have become very common. If not totally familiar with the technology, it might be a good idea to do a little research and include the topic in a training session or two.

Basically, under the general heading of solar panels there are two distinct types with two very different functions. The most common are the Photovoltaic panels which generate electricity and then there are the Thermal heating panels which provide hot water and heat swimming pools. Other than the dead load weight they add to the roof, the thermal panels present little concern for fire fighters. However, the Photovoltaic panels are a different issue.

The PVs (photovoltaic) pose an electrical hazard as well as adding weight to a roof structure that may not be optimally designed to handle the additional load. The PVs, during daylight, continue to generate DC current throughout the system even when “turned off” at the solar panel inverter. (usually located next to the main meter). The only way to prevent them from creating DC power during the day is to cover all the panels of the system completely with an opaque material. NOTE: the blue and black salvage tarps normally carried on trucks may not be opaque enough to stop the generation of DC current so check the meter and determine if it is or is not still turning.

In other words, while it may appear that the modules are shut off, they are still charged and therefore also assume the conduit leading from the panels to the meter is charged as well. Caution must be taken to identify the conduit, it may be camouflaged by being painted the same color as the house. While the panels are usually located on only a south facing roof section, the conduit may run into the attic space where its path will be hidden as it crosses from one side of the house to the other. The objective of course is to not cut the conduit. The hidden path of the conduit could be problematic even when cutting ventilation sections on non-panelized sections of the roof.

If ventilation is necessary on a panelized section be careful that ventilation cuts do not occur on trusses on which the system is mounted. As it is, the added weight of the system may cause a rapid and premature collapse of the roof. As another safety tip, be careful not to step or stand on the panels, they are slippery.

Thanks to Capt. Randy Frassetto, Surprise AZ for safety tips. For more technical information addressing Photovoltaic panels click on the following links: and

Pete Adams
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