The commentary in the handbook says
There is no intent or requirement to have a disconnecting means located in each PV source circuit or located physically at each PV module location. Unlike load circuits (e.g., rooftop air conditioners), PV source-circuit conductors may be energized at any time from the PV modules. A centrally located disconnect meeting the requirements of 690.14(C)(1) near the inverter or batteries serves to disconnect the PV source circuits from the other portions of the electric power system.
There has been a concern with the Fire Departments, our's also, the need for a disconnect at the panels in case of fire.
I wiuld contact the local AHJ and ask him what the rules are there.
I suppose the FD could say "OK try to hold that fire down, we will be there right afrter sunset"
A small house fire caused by a solar panel in San Diego last week exposed a potentially dangerous flaw in the building codes of many cities across California, which is pushing for tens of thousands of homeowners to install the generating systems on their rooftops.
Experts say that in most cities, installers are not required to place a switch on the roof to cut power from panels in an emergency ---- leaving firefighters unable to put out certain fires and helpless to stop dangerous amounts of electricity from flowing along wires as long as the sun is shining. Temecula, which requires a separate shut-off, appears to be the sole local exception.
Amy Pavis had a solar-powered electrical fire on her Lake Murray-area home on Wednesday, and it wouldn't go out.
Fed by electricity from her rooftop solar panels, the fire smoldered for hours despite repeated applications of a household fire extinguisher and the efforts of the San Diego Fire-Rescue Department. Only after an electrician arrived to cut the wires leading from the panels were the flames put down for good.
Pavis was home with her two children Wednesday when a painter she'd hired came in reporting "a funny smell." Soon he returned to report smoke coming out of the inverter box, the unit that converts DC power from the solar panels to AC current for the house.
Pavis flipped the cutoff switch to disconnect the power and began calling electricians. After five declined to help, she reached Mark Snyder, a Poway-based master electrician and solar installer. "While on the phone with Mark, the converter box caught fire," Pavis said.
One of the painters emptied a fire extinguisher onto the box, keeping the flames down until the San Diego Fire-Rescue Department arrived. But all the firefighters could do was keep the fire down to a smolder.
Finally Tom Doherty, an electrician dispatched by Snyder, arrived on the scene wearing a fireproof suit and gloves insulated against 1,000 volts of electricity. "When I hit it with a screwdriver, it started arcing and started to burn again," Doherty said. Doherty reached in and cut the wires from the panels. With its source of energy throttled, the fire went out. The fire department estimated the damage at $4,000.
Doherty and Snyder said that if Pavis hadn't been home, or if the workers hadn't noticed the smell, the flames would have heated the metal casing until, eventually, the frame of the house was ablaze. Snyder, who has investigated electrical fires for 25 years, said he's seen 50 solar-fed fires like this one, and on five occasions there was major damage.
Snyder said the fire illustrates a clear failure of building codes governing solar installations, especially given the proliferation of residential solar arrays.
Spurred by state and federal incentives, an appetite for carbon-free energy and a desire to protect themselves against electric rate hikes, California homeowners have been installing solar panels in increasing numbers. San Diego County issued 432 permits for solar installations between July 2008 and June 2009. In the nine months since then, it has issued 760.
Nearly all of these installations include two switches next to or even inside the inverter box: one that cuts AC flowing into the house, and one that cuts the DC current flowing down from the panels. Pavis had an older inverter with the DC cutoff switch in the box, which exacerbated the problem. But Snyder thinks even the two-sided set up is inadequate.
He argues there should be a way to cut DC power right up on the roof, as close to the panels as possible.
"When you throw the breaker in the house, it should cut power on the whole system," he said.
San Diego County follows the state's building codes, which do not require such a switch. In the region, only Temecula has such a requirement, Snyder said. Charlie DeHart, a battalion chief in Temecula for the California Department of Forestry and Fire Protection, said the stricter rule is preferred because firefighters can effectively cut power from the panels. Outside of Temecula, they have to be wary.
"We can safely kill the interior side of the structure, and our folks are still safe," he said. "If they have to go on the roof, they have to know to be careful, unless they have that cutoff switch."
But some industry experts said that's exactly the problem.
Sue Kateley, the executive director of the California Solar Energy Industries Association, a trade group, said DC cutoffs create danger because they mislead firefighters. The solar panels remain energized as long as the sun is up, and they even retain some electricity when it's dark. Putting a cutoff on the roof only neutralizes the wire running from the panels to the inverter box, but it doesn't eliminate the danger to firefighters.
"It's that perception of safety we want to avoid; they think they're safe, when there's potential from getting a shock, and falling off the roof," she said.
Requiring DC cutoff switches remains a subject of debate among electrical engineers nationwide. Gig Conaughton, a spokesman for the San Diego County Department of Land Use and Planning, said the county monitors the national discussion carefully.
Yet no national requirement appears to be on the horizon.
"There's no national movement for DC cutoff switches on the roof," said Bill Brooks, an engineer and electricity consultant who has worked extensively on national electrical standards.
Kateley said there are other solutions to the problem of energized solar cells, but she didn't provide examples. She said the real lesson of last week's solar panel-sparked house fire is that homeowners need to have their systems inspected on a regular basis, to make sure nothing needs replacement or repair. But she also conceded that data on solar panels and safety is still coming in.
"The challenge is, until we had enough systems out there, if we had an incident it was so actuarially insignificant," she said. "There was no generic problem."
In the meantime, Pavis said she isn't sure if she wants to continue being a solar guinea pig. "I had them cut all the wires to both of the panels right now until we find out what the heck is going on," she said. She said it had been a stressful day. "It wasn't fun."
I am going to ask around and see what the thinking is about getting this into our state code. (Fla). The local amendment is probably the fastest way to get this implimented.
I've heard the same thing as far as new code changes. The fires seem to be the reason for taking a new look.
Do you know of any good 'inspection chk lists' for P.V. systems?
What are you looking at during inspection? I want something to hang my hat on.