Fire safety and PV

Even if it’s nighttime and the solar panels have not been exposed to direct sunlight for several days, they still are energized and can kill you. It is estimated that the panels would need to be covered with an opaque tarp for 7-10 days before the panels will “de-energized” down to minuscule levels. (although the handouts specify that this as an option for safety steps - it is not accurate per the presenter)

The final question which was asked really put things in prospective - someone asked that since Califorina is number one when it comes to Solar Panel Syatem installations, “…what do their Firefighters do when a structure fire involves these systems?” Answer was “… they let it burn!”

Fire station burns down for the second time

An early morning Sunday fire on January 11th at a fire station caused 2 million dollars in damage and destroyed all six of it’s fire engines.

This isn’t the first time the German fire department has burned down, in 1994 another fire destroyed the building and all of it’s fire engines.

250 fireman from nearby cities had to drive to the Syke fire station to control the blaze.

Due to the quick response of other fire stations only the vehicle bay and all of the fire fighting equipment was destroyed. The kitchen, offices, and lounges were saved.

One local complained that a fire station that can’t even save it’s own fire engines doesn’t exactly inspire confidence.

Police are investigating the blaze to determine the source of the fire at the fire department.

I wanted to offer some clarity to this discussion. It is an area we all need to know about, but as is often the case; a few misconceptions can spin some VERY tall tales!

I will address the issues one by one:
1. Panels are only energized in daylight. Overcast days too, but NEVER at night. Scene lights will NOT energize the panels.

2. If the panels, or the roof are on fire you will not get shocked by spraying water on them. Put the fire out.

3. The voltages of panels are are anywhere from 24-48 volts each and generate from 125 to 200 watts in optimal conditions.

These panels are "strung" together in series to increase the voltages to 120 vdc to 400 vdc. While 600 vdc is possible, it is pushing the UL ratings of the enclosures, wire, etc.. The current of these strings is usually from 5-9 amps. And that is only when there is a load (or put more simply, the inverter is sending the power back into the grid). If the inverter is off, there is no current only voltage, i.e. open circuit.

4. The inverters that change the power from DC to AC, are powered by AC. If you shut off the main service breakers, the inverter is OFF and there is NO AC power being sent into the structure. There are capacitors in the inverters that can hold a charge for about 5 min, but in the daytime the panels are producing power anyway. When the sun goes down. Everything is de-energized.

Here is the danger: There is ALWAYS energized DC power in the conduit from the panels to the inverter IN THE DAYTIME. So, secure all utilities (per SOP's) and stay away from the panels, and the conduit in the daytime.

5. Do not break a panel with your axe! Each panel in the string could be carrying the FULL VOLTAGE of that string (120-400 VDC), so if you put an axe through it, you will very likely be getting the rest of the shift off! Don't do it....There is no need to do it, vent somewhere else, and kill the utilities at the main panel.

6. There are often junction boxes on the roofs (residential systems), but these do not always have fuses. If you do pull a fuse under load, you can cause a fire. Don't do it...Bad idea.

7. In California, we will not let a house burn because it has PV Panels on the roof. I may not be able to put my hole in the best place, but I will put one in where I can.

As to the comments on water heating systems, they are pressurized to 15 psi if they have antifreeze (food-grade glycol) and up to 60 psi with water only, so while the water can be as high as 180 degrees F, there is not high pressure involved.

A little about how I know this:
I teach classes on FF Safety on PV Systems, have a degree in Solar Technology, and I have PV and Solar water heating systems myself. I am also a member of the California State Fire Marshals PV Task Force.

I hope that helps. The article that started this has caused many people in both the fire service and the solar industry a lot of stress. It makes us look uneducated.

Stay Safe Brothers!

FE Matt Paiss, Truck 13B
SJFD

I had been working with the Arizona Public Service (APS) and the Salt River Project (SRP) on a program to identify high-voltage electrical vaults and substations within Phoenix. About a year ago, Phoenix Fire responded to a reported fire in the basement of a residential high-rise building in downtown Phoenix. After arriving on-scene, firefighters forced entry into an “unmarked basement” and began extinguishing a small fire involving what appeared to be electrical equipment. When the electrical company arrived, it was discovered that the “basement” our fire crews were working in was actually an electrical vault. In addition, the equipment involved was a high-voltage transformer. Fortunately, a lighting strike had damaged the transformers, and they were not energized. Had they been energized, discharging a dry chemical extinguisher on this equipment most certainly would have led to electrical injuries to our firefighters, at the very least.
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In 2002, a firefighter in Switzerland was injured as the result of an electrical shock he received from a PV; fortunately, the injuries were not serious. In 2007, a firefighter in Sedona, Arizona, received an indirect electrical shock while fighting a house fire. In this case, the home electricity was secured at the utility box. The firefighters operating at this incident were unaware that the PV system was still energized.
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It’s also important to remember that environmental factors can affect a PV system’s performance. Cloud cover, smog, and temperature are just a few things that can reduce the amount of electrical energy created by a PV system. Although the time of day and the weather can affect PV performance, firefighters should always treat the system as if it were energized electrical equipment.
Whenever the sun is shining, a PV system is creating electrical energy, and it can’t be turned off. A fire department in California attempted to black out a PV system by using a salvage cover to block out sunlight. The energy created by the system was reduced, but it did not completely block out the sun, and the system still produced enough electricity to shock a potential victim. Firefighters in Germany attempted to cover solar panels with foam to block out the sunlight, with a similar result. Sunlight was able to penetrate through the foam, and the PV system continued to create electrical energy. In this case, the foam kept sliding off the panels. The bottom line for the fire service is to treat the system as any other electrical equipment and assume it’s energized.
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Also, the “hot stick” many fire departments carry on their engines and ladders detects only alternating current; using a hot stick to determine if a PV system is energized will mislead firefighters into a false sense of security because everything between the solar cells and the inverter is direct current. Some PV systems include batteries that store the solar-generated electricity. Do not cut into these batteries, and keep in mind that if they are exposed to fire, they will release corrosive fumes and gases. Additionally, if these corrosive fumes come into contact with certain metals, they will produce explosive gases and toxic fumes. When responding to emergencies involving batteries, always wear full protective turnouts and SCBA.