advances
| solar safety
Firefighters Learn To
Work Around Rooftop PV
By KEN SHEiNKOPf
Ken Sheinkopf has been
working in renewable
energy for 25 years.
He writes the “Ask
Ken” column for SOLAR
TODAY; see page 62.
firefighting
Facts and Fiction
Myth: “Solar panels cannot be shut down; they are
always energized and with
up to 600 volts of DC current.”
FACT: In strong sunlight, a
single photovoltaic panel
on a residential rooftop may
produce up to about 250
watts, typically at 48 volts
(larger panels on commercial
installations may produce
300 watts). That’s enough
power that you don’t want
to put an axe through it.
And you don’t want to cut
through cables, which may
carry high voltage.
Myth: “Even if it’s nighttime
and the solar panels have
not been exposed to direct
sunlight for several hours,
they are still energized and
can kill you.”
FACT: When the light fails,
the panel goes inert. No light,
no current, no danger.
Bottom line: Don’t be afraid
of the panel. Walk across it, if
necessary. Vent the roof next
to the panel, not through it.
in December, a scary post appeared in a website forum
for firefighters, firehouse.com. It said, “What do firefighters do when a structure fire involves these systems
[solar panels on the roof]? They let it burn.”
Why would they do that? It turns out a lot of firefighters
believe they could suffer electric shock while working near
a solar array.
According to Matt Paiss, a firefighter in San Jose, Calif.,
“I recently talked to a firefighter in New York, and his perspective on solar panels is simply that they present a hazard
because he doesn’t know too much about them, and it just
seems to him that the potential for getting shocked while
putting out a fire is a big one. We’ve got to get the right
information out to the fire industry, because otherwise I’m
concerned that they won’t be as aggressive in fighting a fire
on a building with the panels as they ought to be.”
Paiss knows a lot about solar energy. He studied solar
engineering in college and has thermal and photovoltaic
not been exposed to direct sunlight for several hours, they
are still energized and can kill you. It is estimated that the
panels would need to be covered with an opaque tarp for
seven to 10 days before the panels will ‘de-energize’ down
to miniscule levels.”
Paiss is well-placed to set the record straight. “Because
firefighters are more apt to listen to one of their own
explaining these systems, I’m doing my best to help get the
word out,” he said. One way he’s doing this is by writing
about it, and he’ll have an article in one of the field’s major
publications in a couple of months.
Brooks notes that the issue has been blown out of proportion because of the perception of a real hazard. “
Electricity is not put into different categories by firefighters,”
he explained. “To them, electricity means death. Because
standard practice is usually to ventilate the attic and ceiling
areas by cutting through the roof, they need to be sure that
they’re not cutting into a live electric current.”
“We’ve got to get the right information out to the fire industry, because
otherwise I’m concerned that they won’t be as aggressive in fighting
a fire on a building with the panels as they ought to be.”
matt Paiss, firefighter, San Jose, Calif.
(PV) systems on his own home. When the state fire marshall started holding meetings on the PV safety issue in
2007, Paiss called Bill Brooks, a PV engineer and training
consultant in Vacaville, Calif., and said he’d like to help
educate other firefighters. Now he teaches classes on PV
safety for firefighters.
Paiss acknowledged that the issue certainly is real, and
firefighters do sometimes get shocked by line voltage. But
they need to understand that the dangers presented by
the PV systems are usually not as severe as other electrical
issues they deal with, such as overhead power lines, junction
boxes and live cables in burning walls.
“I’ve been following this issue pretty closely for about the
past five years,” Paiss said. “Sometimes I read absolutely
mind-boggling statements.”
The December post on firehouse.com, for example,
included inaccurate comments like, “Solar panels cannot
be shut down; they are always energized and with up to
600 volts of DC current. If you put an axe through them
to open up a roof to vent, you’re putting the axe through
600 volts. Even if it’s nighttime and the solar panels have
The main concern firefighters have in these cases, especially on residential rooftops, is getting a shock and suffering
involuntary movements that could cause them to fall to the
ground. A rooftop disconnect would solve only part of the
problem — it would still leave a voltage on the panel side
of the circuit.
Brooks and others in the solar industry in California
have actively been working on this issue since 2007. At the
request of the governor’s office, the California Solar Energy
Industries Association has organized a number of meetings
to draft photovoltaic installation guidelines. The draft document requires roof access for safe fire suppression and rescue
operations. The key paragraph, Brooks says, requires that
solar panels be set back several feet from the edges and peaks
of roofs. This reduces the area for solar panel installation but
provides room for emergency personnel to work around the
array. It also allows for roof-peak venting in case of fire.
Brooks also notes that firefighters must understand the
difference between water-heating and PV systems, since
there isn’t the electrical problem with the water heaters.
“It’s really education,” he said. “The bottom line is that if
