[RE-wrenches] More Issues with Parallel Sol-Ark 15K System

[Poole, Jharen via RE-wrenches]

Our inverters utilize CANbus communications for establishing parallel operation 
between multiple Sol-Ark inverters. CANbus communication operates as a serial 
communication protocol. In this setup each inverter in the setup is linked via 
a parallel communication cable forming a daisy-chain configuration. If one 
inverter in the chain experiences a shutdown due to a fault, the communication 
chain is disrupted. Consequently, the other inverters will also power down when 
we see this loss, ensuring system protection and safeguarding the customer’s 
investment.

Paralleling must be done at a stage 0 they have to sync and that is done in the 
pre normal mode, functionality wise having them going into sync is extremely 
difficult due to timing issues. It's easier to time it from a stage 0 than to 
do it when one unit is already running.

Maintaining synchronization between inverters is critical; if the inverters 
were to operate out of parallel it can result in conflicts between the 
operation of inverters and desynchronization of the units. This misalignment 
can escalate, potentially causing significant damage to one or more inverters 
and risking harm to other connected equipment.


Best Regards,

Jharen Poole
Applications Engineer II
972-575-8875
[cid:09eb4ba0-f025-49ec-8033-336d60599649]
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Re: [RE-wrenches] NEP PVG wiring

[William Miller via RE-wrenches]

Lloyd:



Thank you for your reply.  That is how I read the instructions for all of
the aforementioned MLPE devices.



I think there is a flaw in the logic here, at least for the NEP and Tigo
products.  It is because both manufacturers offer rail or frame mounting
options.  This is significant for this reason:



If you are frame-mounting an MLPE device it is convenient to connect PV
leads to the MLPE first and you can easily comply with the instructions.



If, however, you are rail-mounting the MLPE it is quite inconvenient to not
be allowed to interconnect the MLPE devices before connecting the PV. You
really need to complete all of the hardware and wiring infrastructure
associate with your mounting system before you bring your modules to the
roof.  It is very awkward to be juggling a panel on the roof to connect it
to rail-mounted MLPE before you are allowed to interconnect the
rail-mounted MLPE devices.



It is my opinion that if your MLPE devices cannot be interconnected, you
should not offer a rail-mount option.



It is important that we use proper terminology for these parts of the
system. “Interconnecting” and “home-runs” are different things:
Interconnecting leads are between devices.  Home-runs are leads run between
the ends of strings of devices and the terminating equipment.  NEP equated
these in their quick start guide and this caused confusion.



I spoke to George with NEP today about this.  I presented this dilemma and
he seemed to understand the conflict.  George told me the concern is that
if an installer connected a PV panel to the series-string output of the PVG
units, damage to the MLPE unit could occur. They do have the same MC4
connectors so this is possible.



I get the concept that even the dumbest mistakes are possible, but it would
be hard to confuse the different connections.  The PV inputs are quite
short and the series-string connections are abundantly long.  Also they are
clearly labeled.  George told me that as long as the home-runs were left
unterminated, the interconnecting leads can be connected prior to
connecting PV without risking damage to the PVG units.



As always, the devil is in the details.  Success is achieved in
understanding and dealing with the details.



William Miller



Miller Solar

17395 Oak Road, Atascadero, CA 93422

805-438-5600

www.millersolar.com

CA Lic. 773985





*From:* Lloyd Hoffstatter [mailto:ll...@sunstruckconsulting.com]
*Sent:* Tuesday, November 12, 2024 7:44 AM
*To:* will...@millersolar.com; RE-wrenches
*Subject:* RE: [RE-wrenches] NEP PVG wiring



Hi William,



The RSD installation instructions mirror those of TIGO and APSmart per
connection order of PV to RSD first.



Best regards,

Lloyd



Lloyd Hoffstatter, M.S. Applied Solar Energy

Director, Sunstruck Consulting

*ll...@sunstruckconsulting.com *

845-657-8132 (office)

914-844-3404 (cell)



*From:* RE-wrenches  *On Behalf
Of *William Miller via RE-wrenches
*Sent:* Monday, November 11, 2024 11:30 PM
*To:* RE-wrenches 
*Cc:* William Miller 
*Subject:* [RE-wrenches] NEP PVG wiring



Friends:



I am repairing a site with NEP PVG RSD devices.  We will be removing all of
the modules and finding out why the system is underperforming and why 2 of
the units are not reporting.



The quick start guide includes this line:  PVG’s PV-lead pairs must be
connected to PV modules before connecting homerun cables between RSD device.



I find this wording confusing.  Homerun cables do not connect between RSD
devices, home runs connect to the PV input on an inverter (Soul-Arc in this
case).



I wish to rail mount the PVG RSD devices, connect the series wiring between
these modules and then connect the PV.  Can I interconnect the PVG units
prior to connecting the PV modules?  This sure would make the process
easier.



Thanks in advance for in any input on working with these units.





William Miller

Miller Solar

17395 Oak Road, Atascadero, CA 93422

805-438-5600

www.millersolar.com


CA Lic. 773985
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Re: [RE-wrenches] NEP PVG wiring

[Lloyd Hoffstatter via RE-wrenches]

Hi William,

The RSD installation instructions mirror those of TIGO and APSmart per 
connection order of PV to RSD first.

Best regards,
Lloyd

Lloyd Hoffstatter, M.S. Applied Solar Energy
Director, Sunstruck Consulting
ll...@sunstruckconsulting.com
845-657-8132 (office)
914-844-3404 (cell)

From: RE-wrenches  On Behalf Of 
William Miller via RE-wrenches
Sent: Monday, November 11, 2024 11:30 PM
To: RE-wrenches 
Cc: William Miller 
Subject: [RE-wrenches] NEP PVG wiring

Friends:

I am repairing a site with NEP PVG RSD devices.  We will be removing all of the 
modules and finding out why the system is underperforming and why 2 of the 
units are not reporting.


The quick start guide includes this line:  PVG’s PV-lead pairs must be 
connected to PV modules before connecting homerun cables between RSD device.

I find this wording confusing.  Homerun cables do not connect between RSD 
devices, home runs connect to the PV input on an inverter (Soul-Arc in this 
case).

I wish to rail mount the PVG RSD devices, connect the series wiring between 
these modules and then connect the PV.  Can I interconnect the PVG units prior 
to connecting the PV modules?  This sure would make the process easier.

Thanks in advance for in any input on working with these units.


William Miller
Miller Solar
17395 Oak Road, Atascadero, CA 93422
805-438-5600
www.millersolar.com
CA Lic. 773985


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