In my area, even after you’ve hauled all the panels up onto the roof and connected them to the system wiring, there’s still more work to be done before you can throw the big red switch to the “ON” position. Before you connect your solar array to the grid the system it needs to be inspected (and approved) by three agencies:
- The city fire inspector The fire department wants to make sure that you’ve followed their guidelines that allows safe access to the roof by emergency personnel if they need to respond to an emergency.
- The city building inspector The city needs to inspect and approve of the quality of the mechanical work (roof mounting points and racking system) as well to ensure that the electrical work is up to code.
- The utility company inspector The utility company also wants to look at the system’s electrical work and components to make sure there’s no potential of damaging the neighborhood’s grid.
Firefighters have a unique interest in the design and installation of a rooftop solar system. In the event of a structure fire the first responders will usually climb onto the roof to assess the situation and often cut large holes into the roof directly over the blaze to vent the heat. Solar installations that have wall-to-wall solar panels make access difficult or impossible. One fire official told me “At some point we may look at a roof (with an out-of-code installation) and declare the structure a loss because we can’t fight the fire. We’d hate if that happened”
Not only is physical access to the roof an issue but there’s also the matter of live wiring on or near the roof. If the fire happens during the daytime those panels will be generating electricity and the circuitry on the roof will be energized with potentially harmful voltages.
As a result, CalFire (the state fire agency better known for fighting wildfires during our dry summers) came up with a set of guidelines for designing “firefighter safe” solar installations. The city of Santa Rosa recently adopted those regulations and any new installation will need to conform to those rules. You can look at the local adaptation of the CalFire rules here
As I mentioned in the first video, the rules for access are straightforward: No panels within three feet from the ridge of the roof to allow ventilation and leave a three foot access pathway from the ground to the roof. This means no more wall-to-wall coverage with PV panels but that’s pretty easy to incorporate into any layout. Here’s my roof:
Leaving the three foot access path turned out to be pretty helpful during the installation; it gave us plenty of room to work when carrying those large panels. I can imagine a firefighter in full gear on the roof needing just as much room to maneuver. On the right is a picture of the ridge setback of the same array (click on the photo to see full size):
The electrical concerns are just as easily addressed. Any current solar system design will include a disconnect switch to remove the rooftop array from the household wiring. This is handy for keeping the system offline during installation and makes for easy disconnection for repairs or in an emergency. The codes call for clear labeling on the disconnect switch and a warning label on the main meter panel:
The last piece of code calls for specific labeling for the conduit. There are two reasons for this:
- For single-inverter systems, even after the disconnect switch is thrown the DC wiring coming down off the roof is still energized. It’s no longer connected to the inverter and no current is flowing but the wires in that conduit are charged to hundreds of volts and any breach of the conduit with a firefighter’s chainsaw or axe will cause a massive short-circuit.
- Conduit on the roof makes for a tripping hazard. For cooling purposes the standard construction technique calls for a standoff of an inch or more to keep the conduit up off of the surface of the roof. The fire code calls for reflective warning labels to be put on the raised tubing to reduce the possibility of tripping.
So there you have it – the rules are simple to understand and have a very important purpose: to make it easier for emergency personnel to safely protect your house if a fire should break out. Even if your local jurisdiction doesn’t have these setbacks and labeling requirements you may want to consider following them when designing your solar PV installation.