[RE-wrenches] Insurance and rapid shutdown

Fri Apr 10 16:30:59 PDT 2026

Hi William
We've also had issue with RSD switches. Most of our issues have been with
Tigo, but another contractor that I know has had issues with the AP smart
RSD switches as well. The irony doesn't escape me that we are installing
expensive products that are supposed to help protect fire fighters, but the
very thing we're installing can cause fires.

I'll take your suggestions to heart.

Thanks,

Vince McClellan

President

NABCEP PV Professional

p: 541-485-8122

a: 860 Conger St. Suite 12,. Eugene, OR 97402

e: vince at solarenergydesgin.com

w: SolarEnergyDesign.com

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On Fri, Apr 3, 2026 at 12:58 PM William Miller via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Below is a message I received off-line a while ago re: AP Smart, along
> with photos.
>
>
>
> I thought I’d contact you off list.  You have been asking about RSD units,
> I wanted to pass along my experience with the AP Smart RSD unit.  I’ll let
> the pictures do most of the talking - see below.  Bottom line, APSmart is a
> nice little easy piece of plastic junk to install and commission.  However,
> when something goes wrong it can be a real pain to ID the fault.  They have
> a little gadget that you have to wave over the conductors to listen for a
> pulse (not always easy on a roof!  I went thru 2 inverters about 6 hrs on
> the phone with SMA (I got ALL sorts of weird errors, but only 1 arc fault),
> 2 weeks of back and forth with AP Systems/Smart.  After I finally got the
> arc fault, in an act of desperation, I started tearing the array apart at
> significant expense and much frustration by my client (he totally lost
> faith in solar and had been wanting it for years) I finally found the
> problem.  Luckily this one was on a new install on a metal roof and not on
> a system that had been through a few seasons with build up of leaf detritus
> under the array on an asphalt shingle roof.  I’ve been at this for 17yrs
> now and have never had a piece of equipment fail this catastrophically -
> especially a piece of unnecessary safety equipment.  Their tech support
> engineer, while well meaning, is extremely difficult to understand due to
> language barrier and completely failed to take any responsibility for this
> failure which could have resulted in a house fire and who knows what else….
> My strong recommendation is to limit the use of any RSD unless pressed to
> do so by an AHJ.  It’s my opinion that these units should be at least in
> metallic enclosures.  I worked at Tigo back before RSD was a “thing” and do
> see the advantages, but I just think (like BB) that there are more
> downsides than up at this point in time given the available tech.  I keep
> this unit in my van and show every AHJ then ask them to tell me what they
> want me to do in writing.  I am not going to be on the hook the
> consequences of such a catastrophic failure.
>
>
>
>
>
>
>
>
>
> William Miller
>
> Miller Solar
>
> www.millersolar.com
>
> CA License C-10 77398
>
>
>
> *From:* Tyrone Houck [mailto:tyronehouck at gmail.com]
> *Sent:* Friday, April 3, 2026 10:17 AM
> *To:* william at millersolar.com
> *Subject:* Re: [RE-wrenches] Insurance and rapid shutdown
>
>
>
> Thanks for sharing. I've asked this group multiple times for any anecdotes
> or pictures of APSmarts failing and never recieved any response. Tigo
> failures are mentioned often. Personally, I've installed upwards of 1000
> APs  with no issue(I don't make a habit of stress testing them by
> repeatedly hitting the switch during peak production though). All that
> said, I wouldn’t bother installing them in a situation that didn't warrant
> RSS.
>
>
>
>
>
>
>
>
> On Fri, Apr 3, 2026, 10:06 AM William Miller <william at millersolar.com>
> wrote:
>
> I have seen photos of one AP Smart RSD that had melted and burst into
> flames.
>
>
>
> The job they are required to do : open a high voltage, arc sustaining
> circuit under load is a difficult task to accomplish, especially in a small
> package in an extreme environment.
>
>
> William Miller
> Miller Solar.com
> 805-438-5600
> www.millersolar.com
>
>
>
>
>
> On Fri, Apr 3, 2026 at 10:00 AM Tyrone Houck <tyronehouck at gmail.com>
> wrote:
>
> If considering retrofitting rapid shutdown I would recommend APSmart. I
> have never had any failures or heard of anyone else who has.
>
>
>
>
>
>
>
>
> On Fri, Apr 3, 2026, 8:05 AM William Miller via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
> If he wants to be more assured of filing an insurance claim he should
> install RSS.
>
>
>
> Seriously, the equipment has a bad safety record. I would recommend a
> safety inspection and a modern charge controller with arc flash and ground
> fault detection over RSS.
>
> William Miller
> Miller Solar.com
> 805-438-5600
> www.millersolar.com
>
>
>
>
>
> On Fri, Apr 3, 2026 at 7:46 AM Drake Chamberlin via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
> Hello All,
>
>
>
> A client, for an off grid system, is in an area with no code requirements
> nor inspections. He is concerned that if he does not get rapid shutdown, it
> could affect his ability to get an insurance claim paid, if ever needed.
>
>
>
> The array is on a separate utility building that houses a water pump and
> tank as well as the inverter and batteries. Since there is more in the
> building than just solar related equipment, RS is technically required.
>
>
>
> Has anyone ever had to deal with this issue?
>
>
>
> Thank you,
>
>
>
> Drake
>
>
>
>
>
> --
>
> *Drake Chamberlin*
>
> *Athens Electric LLC*
>
> *Ohio Electrical Contractor’s License 44810*
>
> *NABCEP Certified PV Installation Professional*
>
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