[RE-wrenches] PREVENTING Another PV fire

Fri Nov 12 11:18:28 PST 2010

All,

i don't know the cause behind the Meridian Winery situation, but Bill's
comment offers a particularly good opportunity for a teaching or refresher
moment...

The "blown up combiner and melted-down modules" caused by reversed polarity
is way more common than it should be. And it is 100 percent preventable. One
hundred percent!

The damage, in these cases, cannot occur without the fuses installed in the
combiner or re-combiner. As far as i'm concerned, any manufacturer who
actually ships a combiner product with the fuses installed is guilty of
negligence. Including inverter manufacturers, and especially the central
inverters with the integral re-combiners. i've personally told many
manufacturers how i see this over the years. The funny thing is, every
single one i've had these conversations with admits that reversed polarity
installations has caused them quite a bit of headache and cost. Quite a bit
of frustration in some cases. Most of these folks say that the costliest
part is that the installer insists he installed it correctly <<< ya think?
>>> and, at the end of the day, it's hard to prove he didn't and they want
to keep a customer, so replacements are shipped... Often at reduced or no
cost to the installer. Why anybody would want to lose money in order to keep
a lying customer is beyond me. But it goes farther than that...

Why in the world would a manufacturer want to ship a product in a state that
increases the potential for disaster in the first place? Why don't they
include specific instructions for testing individual input circuits before
installing fuses? Why don't they include a basic commissioning form with
every combiner? Checklist, basic project data, and measured values... It's
not that hard.

i advise that they SHIP COMBINERS WITH ALL FUSES REMOVED. Most ignore this
simple advice... How many more catastrophic events is it gonna take before
they adopt this practice? Probably just the one where they get sued for
negligence and lose.

The larger these systems get, the higher the absolute danger. One of the
worst potential situations is a reversed polarity in a feeder between a
string combiner output and the re-combiner input. A combiner full of reverse
polarity strings, on one half of a quasi-bi-polar array, is on a comparable
scale of bad. The more re-combiner input circuits there are, the bigger the
meltdown. i've seen the damage caused by this condition in more cases than i
care to think about... It ain't pretty. And it's really expensive. And,
again, it's 100 percent preventable. There is no excuse for this happening.
NONE!

i urge each of you to review your practices and, if you haven't already,
adopt the following rule:  NO FUSES IN ANY COMBINERS UNTIL ALL ASSOCIATED
CIRCUITS HAVE BEEN CHECKED FOR POLARITY AND GROUND FAULTS, AND HAVE THEIR
VOC MEASURED AND CONFIRMED TO BE CORRECT.

Measured and recorded. On a form. Then reviewed to make sure the measured
values look like the expected values. In addition to preventing catastrophic
meltdowns and job delays, there are other very important safety aspects as
well. Like the fact that this engages somebody's brain before the switch
gets thrown. Like the fact that, as long as the fuses are out of the
combiners, the incident energy on any given circuit is limited to just that
circuit and doesn't include the neighboring circuits. Like the fact that you
will find and fix any small "oopsies" before they become big "Oh Shirts!"
and 911 calls.  

None of us are perfect and never will be. Our installers are never gonna be
perfect. Hell, the equipment ain't gonna be perfect. We need to take
responsible steps to minimize the negative impacts of imperfection.

Any qualified person who energizes power distribution systems, without
checking polarity and voltage of all sources at a minimum, is either not
truly qualified or negligent.

So, which is it? Each of the worst cases of reversed polarity meltdown, that
i've personally dealt with, were done by journeymen electricians working for
a C-10 or equivalent. All but two of them have been union shops. Qualified?
They each insisted that they are the most qualified... Arrogant bravado and
blustery bull-stuff from just about every electrician involved, in fact.
Couldn't be their fault, they are the best electrician ever... Even after
they obviously blew stuff up. i'll take them at their word and say they were
negligent.

Get your checkbooks out, boys... There's some repairs to be made... Oh,
wait... You're just the employee and this is your boss' problem? And your
boss can't write a check for a half million dollars? Guess you need to call
your boss' insurance carrier... Glad nobody got hurt or dead as a result of
your negligence... This time. i am bummed that the customer is now scared of
PV and the job is severely delayed and we can't get enough replacement
modules of the same model and now the bank and insurance companies are
making us do $50,000 of additional testing and inspections so the module
manufacturer will honor the warranty for the "undamaged" modules and all the
internal time and resources that this has cost and the PR problems... Yeah,
that stuff is all a real bummer. 

And those are the realities. Beyond just the physical damage to modules and
combiners and wiring and roofing... There are all these other costs.
Big pricey problems because two lousy wires are reversed. Problems which
would have been prevented if the fuses were not installed until AFTER
polarity and voltage were checked. TAKE THE DAMNED FUSES OUT!

>From an electrical safety standpoint, the safest guy i ever worked with in
solar was absolutely petrified of electricity. He knew two things about
electricity... That he couldn't see it and it could kill him. He used to say
he preferred rattlesnakes to electricity 'cause you can see and hear a
rattlesnake before it bites you. He worked all over the US on jobs of all
types and sizes. Residential to utility scale. He terminated thousands and
thousands of conductors, though he wasn't an electrician. He made up
thousands and thousands of circuits over ten years in the trade. He claims
that he never got shocked or shorted anything out even once. The reason? He
knew what he didn't know. He made sure that he knew exactly what was
connected to everything he touched and, if he was ever unsure, he had
somebody else verify. He communicated with co-workers and verified that both
ends of wires were marked the same. Basic, simple, fundamental things. If he
had any doubts about whether or not he did something correctly, he brought
it to somebody's attention so they could check it out before anybody got
hurt or anything got damaged. If he didn't like or understand the situation,
he wouldn't work on it. If he saw fuses installed in something, he would not
touch it. Plain and simple. He saw plenty of other people get shocked or
short something out, and he didn't want anything to do with that. This guy
had a truckload of machismo, but he didn't let that get in the way of asking
for help or doing a safe job. There's a lesson in here.

People, people, people... If a combiner shows up with fuses installed, pull
them out, put them in the job-box, and leave them there until you have fully
commissioned each string and feeder. This is super critical for inverter
integral combiners and re-combiners. i also insist on opening the DC
grounding jumper when the inverter lands onsite, too. But that's another
conversation.

Be safe out there. Keep your workers and customers safe. Pull those fuses.
Tell your suppliers to ship fuses separately from combiners. Bang on
manufacturers to ship with fuses out!

Pray for Fuse Free Combiners!

Solar Janitor

  _____  

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Bill Brooks
Sent: Thursday, November 11, 2010 10:06 AM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] Another PV fire

William,

Apparently this fire was started by miswiring a combiner box. Most likely
reverse polarity of a string or whole combiner box feeder at the inverter.
Details to come.

Bill.

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of William
Miller
Sent: Thursday, November 11, 2010 8:21 AM
To: RE-wrenches
Subject: [RE-wrenches] Another PV fire

Colleagues:

This is starting be more common.  Below from our local paper:

Rooftop solar panels catch fire at Meridian Winery east of Paso Robles

Solar panels on a building at Meridian Winery east of Paso Robles caught
fire Wednesday morning, according to Cal Fire.The panels were on the roof of
the building where red wine is fermented. Firefighters are trying to see if
the flames spread to other solar panels, but have to wait for the
electricity to be turned off.
Meridian Winery is located at 7000 Highway 46 East. The fire was reported at
10:25 a.m. 

William Miller

Please note new e-mail address and domain:

William Miller 
Miller Solar
Voice :805-438-5600
email: william at millersolar.com
http://millersolar.com <http://millersolar.com/> 
License No. C-10-773985

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