[RE-wrenches] RSD Troubleshooting Help

[Carl Adams]

Rick,
I was recently troubleshooting a similar problem.  Open circuit voltage on
all strings was as expected but under load one string was showing almost no
power.  Tracked this down to a failed APSmart device which had clear signs
of thermal damage.  Pictures 1.1 and 1.2.  .
A second failed unit some months later had a thermal failure and this one
toasted the module.  Picture 2.1.

These devices can make it difficult to do any meaningful string level
testing.  The devices output a nominal 0.7 volts in open circuit
conditions.  That documentation says this voltage reading is *+* 25%, so in
theory you could have a number of devices which were not working and your
string voltage would not indicate that.

APSmart does make a test device which can help you verify the
functionality.  The device is called  RSD-EYE+ Detector.  You can contact
YI Kang , *APPLICATION & TECHNICAL SUPPORT MANAGER,*
*MLRSD *at APSmart for additional information.    737.218.8486
[image: FailedAPSmart1.2.jpg]
[image: FailedAPSmart2.1.jpg]
[image: FailedAPSmart1.1.jpg]
With Kind Regards
Carl Adams, President
SunRock Solar, LLC
513.290.9072 (mobile)
513.766.6025 (office)



On Mon, Jun 21, 2021 at 11:55 AM Lloyd Hoffstatter <
lloyd at sunstruckconsulting.com> wrote:

> Rick,
> I would check with SMA to make sure you have the latest firmware.
>
> Best regards,
> Lloyd
>
> Lloyd Hoffstatter
> Sunstruck Consulting
>
> Get Outlook for iOS <https://aka.ms/o0ukef>
> ------------------------------
> *From:* RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org> on behalf
> of rick at solshineenergy.com <rick at solshineenergy.com>
> *Sent:* Monday, June 21, 2021 11:42:36 AM
> *To:* RE-wrenches <re-wrenches at lists.re-wrenches.org>
> *Subject:* [RE-wrenches] RSD Troubleshooting Help
>
> Wrenches,
>
> I’m in need of some troubleshooting help on a newly installed system with
> rapid shutdown. System consists 2 SMA SB5.0-1 SP-US-41 (RSD version), RSD
> devices are APS RSD-S-PLC. Each SB is configured with two strings of 9.
> Modules are REC Alpha 360s.
>
> This system was fully functional for about 1 week before things went awry.
> Initial symptoms were that one of the two strings read 0V 0A on the display
> while the other read ~315V, 5A. The RSD devices output ~700mV each when in
> the off mode (a nice verification feature). I’m reading the correct voltage
> - 6.75V - on both strings when in off mode. Once the Sunny Boy comes on
> line I’m reading around 10V on the faulty string and the correct voltage -
> ~315V - on the other string.
>
> The above seems to indicate that each RSD is getting sufficient DC voltage
> from the module. Short of pulling each module and doing a visual check what
> else can I look at? How do you isolate a faulty RSD device?
>
> And as luck would have it, everything is functional at the moment.
>
> Thanks,
>
> rick brown
> SolShine Energy Alternatives, LLC
> Electrical & Solar Contracting Services
> www.SolShineEnergy.com
> Check, Virginia 24072
> O: 540.235.3095
> M: 540.808.9502
>
> VA Class A Contractor Lic# 2705147660
> VA Master Electrician Lic# 2710062762
> VA Alternative Energy Systems Installer
> NABCEP Certified PV Installation Professional 110112-21
>
>
>
>
>
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