[RE-wrenches] Sol-Ark 15K Gen on Grid Terminal (with GTBB)

Poole, Jharen Jharen.Poole at sol-ark.com
Mon Jul 7 14:48:19 PDT 2025 

In most cases I would expect the generator to be detected as we tend to start a generator manually in some of our in house testing and the inverter sees it as a generator and there is no sell back. Although with there being variability of generators out in the field there could be a chance encounter where you could run into a situation where the generator could be mistaken as the grid if you were to manually switch the generator in this setup compared to letting the inverter initiate the start of the generator.

I would think of this as having a sure two-step way to make sure the inverter is interpreting the power that is received by the generator as the actual generator. The first step is to have the inverter test the power being received through the grid terminal to determine if the power is from a generator or the grid. If the generator happens to make it pass this initial test from the inverter and is still seen as a grid, then the two-wire start is the second confirming factor to truly make sure the power is coming from the generator.

Best Regards,

Jharen Poole
Applications Engineer II
972-575-8875
[cid:d73acd52-41a4-4305-87d5-012b9d135cf6]
________________________________
From: Jason Szumlanski <jason at floridasolardesigngroup.com>
Sent: Monday, July 7, 2025 3:24 PM
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Cc: Poole, Jharen <Jharen.Poole at sol-ark.com>
Subject: Re: [RE-wrenches] Sol-Ark 15K Gen on Grid Terminal (with GTBB)

Caution: This email is from an external source.


That is interesting. What happens if someone starts the generator manually and manually engages the transfer switch to the generator position? Will the inverter still detect it as a generator, or will that only happen if the 2-wire start is being called for?

Jason Szumlanski
Principal Solar Designer | Florida Solar Design Group
NABCEP Certified Solar Professional (PVIP)
Florida State Certified Solar Contractor CVC56956
Florida Certified Electrical Contractor EC13013208


On Mon, Jul 7, 2025 at 4:07 PM Poole, Jharen via RE-wrenches <re-wrenches at lists.re-wrenches.org<mailto:re-wrenches at lists.re-wrenches.org>> wrote:
For a setup such as this, it is recommended that the generator is started using the inverter’s 2-wire start function rather than a manual startup. We also want to make sure that the grid signal, gen signal, and gen connected to grid input settings are enabled on the inverter to ensure proper detection and operation. I wouldn’t recommend using this setup on a manual start with large generators rated 45kW or higher and are hospital grade. These tend to produce extremely clean power and can mistakenly be identified as the utility grid, which can interfere with its ability to properly determine the source of the input and affect the system behavior.

If you're using a typical residential generator with the recommended startup configuration, and the generator is called upon, the inverter will display a generator icon on the screen once it detects generator power (on the latest firmware). Although the “grid sell” setting remains enabled, the inverter is programmed to prevent power from being exported back to the generator. During a grid outage, it will operate using generator power, and once utility power is restored and detected, the inverter will automatically resume normal grid sell operations.

Best Regards,

Jharen Poole
Applications Engineer II
972-575-8875
[cid:ii_197e68ebc1a5e53039b1]
________________________________
From: RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org<mailto:re-wrenches-bounces at lists.re-wrenches.org>> on behalf of Jay via RE-wrenches <re-wrenches at lists.re-wrenches.org<mailto:re-wrenches at lists.re-wrenches.org>>
Sent: Thursday, July 3, 2025 4:11 PM
To: RE-wrenches <re-wrenches at lists.re-wrenches.org<mailto:re-wrenches at lists.re-wrenches.org>>
Cc: Jay <jay.peltz at gmail.com<mailto:jay.peltz at gmail.com>>
Subject: Re: [RE-wrenches] Sol-Ark 15K Gen on Grid Terminal (with GTBB)

Caution: This email is from an external source.


Sounds like what they want the sol ark can’t do.

I think either the eg4 flexboss and MID or the AIO might work.



On Jul 3, 2025, at 2:33 PM, Jason Szumlanski via RE-wrenches <re-wrenches at lists.re-wrenches.org<mailto:re-wrenches at lists.re-wrenches.org>> wrote:


That might be their recommendation, but it doesn't stop someone from manually starting the generator when the utility is down. Their wiring diagram leave a lot to be desired in terms of how program the system in this configuration.

Even if they strongly recommend that in webinars, it still isn't clear to me if Grid Sell is automatically disabled when the 2-wire start relay is closed. Honestly, I wouldn't trust the answer from a random tech support agent, especially with various firmwares floating around.

This is just another example of poorly documented and ambiguous operational control that plagues all of the all-in-one inverters.


Jason Szumlanski
Principal Solar Designer | Florida Solar Design Group
NABCEP Certified Solar Professional (PVIP)
Florida State Certified Solar Contractor CVC56956
Florida Certified Electrical Contractor EC13013208

On Thu, Jul 3, 2025, 4:14 PM Lloyd Hoffstatter <lloyd at sunstruckconsulting.com<mailto:lloyd at sunstruckconsulting.com>> wrote:
Sol-Ark strongly recommends only using a line side generator under inverter 2 wire control and with AC coupled inverters off, per several webinars.
Best regards,
Lloyd

I’m lLlCOGet Outlook fo<https://aka.ms/o0ukef>
________________________________
From: RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org<mailto:re-wrenches-bounces at lists.re-wrenches.org>> on behalf of Jason Szumlanski via RE-wrenches <re-wrenches at lists.re-wrenches.org<mailto:re-wrenches at lists.re-wrenches.org>>
Sent: Thursday, July 3, 2025 3:10:07 PM
To: RE-wrenches <re-wrenches at lists.re-wrenches.org<mailto:re-wrenches at lists.re-wrenches.org>>
Cc: Jason Szumlanski <jason at floridasolardesigngroup.com<mailto:jason at floridasolardesigngroup.com>>
Subject: Re: [RE-wrenches] Sol-Ark 15K Gen on Grid Terminal (with GTBB)

This guy wants the smart load capability, too.


Jason



On Thu, Jul 3, 2025 at 8:42 AM Jay via RE-wrenches <re-wrenches at lists.re-wrenches.org<mailto:re-wrenches at lists.re-wrenches.org>> wrote:
It’s got generator input terminals.
Why not use them for the generator?


On Jul 3, 2025, at 5:05 AM, Jason Szumlanski via RE-wrenches <re-wrenches at lists.re-wrenches.org<mailto:re-wrenches at lists.re-wrenches.org>> wrote:


The attached wiring diagram from the manual shows both a generator and grid connected to the Sol-Ark Grid input with a transfer switch to select between grid and generator.

Question: If you program the inverter for GEN on Grid Input and allow Grid Sell, how would the inverter know what the input source is and prevent selling to the generator inadvertently?

I suppose if it is an automatic transfer switch and the two wire start is called for, the inverter might stop grid selling when calling for the generator (but I'm not sure if that's the case). In any case, that's not a failsafe solution because the generator could be started and selected manually with the transfer switch and the inverter would not know it.

I have someone insisting that Sol-Ark supports this configuration with Grid Sell enabled. I can't imagine that is the case. At a minimum, it would be bad practice.

In my opinion, the interface should disallow Grid Sell altogether when GEN on Grid Input is selected. Maybe it's already doing that internally, but it isn't clear at all from the interface or the manual.

Of course, the Off-Grid section of the manual does tell you to not use the Grid Sell option.


Jason Szumlanski
Florida Solar Design Group


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