When firefighters approach a burning building, the sight of a photovoltaic array on the roof is the equivalent to a skull and crossbones. PV panels are always electrically “hot” whenever light is shining on them. If the building is on fire, the status of electrical wires from the PV array is unknown; you could be looking at live wires protruding from the roof. One panel can generate enough voltage and current to kill a person. As if firefighters don’t have enough danger in their lives!
German company TOPinno GMBH has developed a small heat-sensitive fuse for PV panels that will electrically disconnect the panel under fire conditions. The small fuse can be integrated into the PV module itself, so it doesn’t complicate the installation process. Each panel would include one fuse that acts as a DC disconnect in the event of a fire, preventing the panel from sending its power to the wires.
The patent application is in German, but with the help of Google Translate, I was able to figure out the basic operation. Essentially it’s a cylindrical spring-loaded normally-closed switch with axial leads. The sides have polyamide, a solder-like adhesive that melts when exposed to excessive heat, allowing the spring to move the plates apart and open the switch.
It remains to be seen whether PV module manufacturers will integrate these fuses - currently selling for $50 each - into their modules. Even if they do, it doesn’t solve the problem of uncertainty on the part of the firefighters. How would they know that these devices are located on the PV modules? I think they’ll still err on the side of caution and avoid the roof. There’s no question that this problem needs to be addressed by the PV industry, and while this device seems like a good first step, it’s only a part of a comprehensive solution.
Image: TOPinno GMBH