[RE-wrenches] Tigo TS4-A-F

[William Miller]

Zeke:



When this subject came up one of the wrenches replied to me off-list and
shared photos of an Alps RSD that had burned up.  He said tech support was
of little help.



Since then I have heard similar stories about Tigo products.



I think the problem is trying to interrupt high voltage / high current PV
DC under load.  To do this with a mechanical switch you would see large
blades surrounded by arc chutes, plastic shields and a metal can.  Doing
this switching in a small plastic nodule seems impractical.



I am the last one to discount safety equipment--electrical fires kill a lot
of people.  However I am convinced that the RSS requirement preceded the
availability equipment to implement the requirement and that gap has not
closed.  Now with UL3471 diluting the seriousness of hazard levels, RSS
seems even more ludicrous.  It is especially onerous to require module
level RSS on ground mount arrays.



Even more galling is the inability to complete a job I am in the middle of
because there is apparently a nationwide shortage of RSDs.



William



Miller Solar

17395 Oak Road, Atascadero, CA 93422

805-438-5600

www.millersolar.com

CA Lic. 773985





*From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
Behalf Of *Zeke Yewdall via RE-wrenches
*Sent:* Tuesday, November 18, 2025 10:52 AM
*To:* RE-wrenches
*Cc:* Zeke Yewdall
*Subject:* Re: [RE-wrenches] Tigo TS4-A-F



Exactly what kinds of failures have people been having on the APsystems RSD
units?  That's what I've been using when I encounter a roof (mostly because
of availability with my distributors, but also being able to easily tuck
them into the channel instead of having to mess with bolts or clips).  I
have not had any failures that I know of yet... but depends on what their
failure mode, failing open or closed or what.  If they fail closed, it
would not be apparent till someone tested or tried to use the RSD system.



Zeke



-- 

Zeke Yewdall

PV Engineer

NABCEP #031508-89

zeke at darkforestsolar.com

303-523-3592
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