PV Fires - Installer Error??? [RE-wrenches]

[Gary Higbee, Solutions from the Land]

Yes, equipment problems can present "spectacular" failures. About a month
ago I got the call nobody wants to hear. A client called to say that the
smoke alarms had gone off in his then-unoccupied house, that the fire
department was on the way, and that he hoped he'd have a house left when he
got there. Conversations en-route confirmed that the AEI Multimode 5000
inverter was the failure point.

The fire department followed the labels (very important) on the house when
securing outside power, and made their way into the equipment room. Only
after they powered-down the equipment did the smoke stop belching.

Part of the power board on the inverter was completely delaminated, and
everything was covered in black crud. Interestingly, though, none of the
ribbon cables were melted, so I don't think there was an actual fire. I
wonder what would have happened, though, had there not been such a quick
response. If I had a big 48-volt battery bank and a few kW of PV laying
around I'd hook it up again in the driveway, turn on the video camera, and
see!. Would it actually start on fire inside? Would any flames get to the
outside? Would it continue to smolder until something burned through and
opened a circuit, or shorted out and tripped the 175A disconnect or one of
the PV input breakers? If anyone has any ideas for an experiment, I've got
the old machine, though the point may be moot because we may never see these
inverters again (later).

The installation (see www.oceansolar.com) was robust, with a full array of
those wonderful Outback components, and the room has thick plaster walls.
The inverter, coupled with a 5.2kW STC multi-aspect PV array, had worked
fine since it was installed last Spring, and we were impressed with it.
Then, a couple weeks or so before the event the machine quit. Working with
the factory led to upgrading the processor, running a calibration, and then
tightening some screws on the power board. It started working again, ran
fine while monitored for a time, and continued running fine until the bells
went off.

Then, in the midst of calls to AEI they announced bankruptcy. Fortunately
Mark Robinson (Director of Customer Support) and Robert Wills (V.P. of
Engineering) were helpful through this, and Rob personally spent a great
deal of time working through a replacement machine--with numerous revisions,
including a different power board construction.

It's tough to see a machine, and a company, go down like this. I sure hope
we get a lot of kW out of the replacement inverter!

WHAT'S TO BE LEARNED HERE?

* We need more testing?
* We need disclosure from companies of known failures?
* We should ensure that installations have all the safety stuff we can think
of (this did)?
* We make sure mounting locations are highly fire-resistant (this is)?

Maybe it is that sometimes UL-listed production equipment breaks, sometimes
spectacularly, and that we do our best to insure a solid and safe
installation, so that the damage is contained if there is such a failure. It
is heartening to note that this sort of failure seems rare.

Thoughts?

A version of this text will appear soon in the "What we've Learned" section
of the www.oceansolar.com web site soon. I haven't decided whether to put
burned inverter pictures there, yet. There will also be an update of our
wind machine experience, including a subjective evaluation of unacceptable
noise we heard while running the Proven WT600. As well, we'll detail a
failure of the stop switch on a small wind turbine, a theory as to why this
happened, and why we may want to considerably oversize these switches.

Gary Higbee

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