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Temporarily turn off selling

Posted: Mon Dec 09, 2019 7:15 am
by Gamebrewer
I have a radian GS8048 that the installer configured for ac coupling. I don’t have my Netmeter yet so I cant sell back power. How do I need to change my configuration to temporarily turn off selling power back so I can use my system for now? Thanks!

Re: Temporarily turn off selling

Posted: Mon Dec 09, 2019 7:48 am
by Kurt Lundquist
If the entire array is AC coupled you can disable selling power by turning off the AC breaker that feeds the micro-inverters.

-Kurt

Re: Temporarily turn off selling

Posted: Tue Dec 10, 2019 2:25 pm
by Gamebrewer
Thanks Kurt. Sounds like I need to describe situation better

I have grid power going to the radian that feeds a sub panel of loads. The sub panel is also fed from the microinverters on the panels. If there is more power going to the sub panel from the microinverters than the load needs the excess power it fed back to the grid by the radian. I don’t want the excess power to be fed back to the grid. It seems like I should be able to configure the radian to not sell that back.

Any thoughts. Thanks!

Re: Temporarily turn off selling

Posted: Tue Dec 10, 2019 2:40 pm
by Mike Curran
What about setting the Radian's AC input mode to "generator"? That would prevent it from selling but I'm not sure what drawbacks it might have...

Re: Temporarily turn off selling

Posted: Tue Dec 10, 2019 3:01 pm
by Kurt Lundquist
Gamebrewer wrote:
Tue Dec 10, 2019 2:25 pm
The sub panel is also fed from the microinverters on the panels.
Turn off the breaker in the sub-panel that goes to the Micro-Inverters. They cannot sell if there isn't an AC source to sync to.
Mike Curran wrote:
Tue Dec 10, 2019 2:40 pm
What about setting the Radian's AC input mode to "generator"? That would prevent it from selling
When AC coupled the Radian isn't really selling anything. The micro-inverters are doing the selling. When connected to the Grid the AC input and AC output on the Radian is common. The Radian cannot tell the power that is provided to the output panel by the AC coupled array to NOT flow back to the input.

The only other option would be to drop the grid at the Radian input and operate as an Island. When islanded the Radian can frequency shift to reduce the AC coupled array power output to a level that is acceptable to the battery bank. That is about all the control the Radian has over the other inverter system.

Keep in mind the Radian only sells excess power that comes in on the DC bus. Since PV is AC coupled nothing is directly feeding the DC bus so there is nothing for the Radian to sell. If PV, Wind, or Hydro were DC coupled to the system that would be a different story.

Cheers,

-Kurt

Re: Temporarily turn off selling

Posted: Tue Dec 10, 2019 4:17 pm
by Mike Curran
Thanks for that, Kurt. =D> Always good to get the right answer from an OB expert. Glad you chimed in.

Re: Temporarily turn off selling

Posted: Wed Dec 11, 2019 5:44 pm
by Gamebrewer
That helps so much. My installer has been useless. Thanks for taking the time to help us. Jeff

Re: Temporarily turn off selling

Posted: Thu Dec 12, 2019 7:31 am
by Kurt Lundquist
Happy to help. Sorry to hear about the installer. When you have time feel free to post your system details like PV array with # of modules and size, and battery bank with make/model and number of batteries. This is good info to include in your user profile. Others will use that info to help quickly answer questions you might have.

Cheers,

-Kurt

Re: Temporarily turn off selling

Posted: Thu Dec 12, 2019 8:12 am
by Gamebrewer
I’ll do that. I had a thought. If the ac input is a pass thru will my batteries charge from the panels if I have a power outage?

Re: Temporarily turn off selling

Posted: Fri Dec 13, 2019 7:37 am
by Kurt Lundquist
The battery can charge if the loads on the critical load panel are less than the power output from the AC coupled PV array. I haven't looked at the spec in a long time but I think your PV array has to push less than 3000W back through the GS4048A Inverter to ensure the battery charger circuit doesn't get fried. How big is your PV array?

-Kurt

Re: Temporarily turn off selling

Posted: Sun Dec 15, 2019 8:38 am
by Gamebrewer
There are 22 300w panels going to the radian. That sounds like it could be a problem.... I haven’t had time to upload my configuration to my description.

Re: Temporarily turn off selling

Posted: Sun Dec 15, 2019 9:12 am
by Mike Curran
This AC coupling app note says up to 6000 watts can be connected: https://documentcloud.adobe.com/link/tr ... 0e96067769
Screenshot_20191215-120147.jpg
But, this note was written for OB's remote operated circuit breaker (ROCB) AC coupling solution.
Bigger but :smile: :

OB Tech support told me this:
Screenshot_20191215-120737.jpg
And this was written for the newer frequency- shifting acc approach with a Skybox. Not sure if it applies for you.

Re: Temporarily turn off selling

Posted: Mon Dec 16, 2019 7:47 am
by Kurt Lundquist
Mike Curran wrote:
Sun Dec 15, 2019 9:12 am
This AC coupling app note says up to 6000 watts can be connected
Gamebrewer has the 1/2 size GS4048A Radian so it can only handle 1/2 of the GS8048A rating (3kW vs 6kW). AC coupled or not the Radian's charging circuit can only handle so much power. For AC coupled array sizing I would shoot for 80% of the inverter's charger rating.

For this setup, I would only AC couple 10 panels. The rest should be tied into the AC input panel side of the system.

-Kurt

Re: Temporarily turn off selling

Posted: Mon Dec 16, 2019 4:56 pm
by Gamebrewer
I got very lucky and they originally ordered the 4048 but realized the error and installed the 8048. They just never updated my paperwork. I’m going to update my system description to fix that.

Re: Temporarily turn off selling

Posted: Mon Jan 20, 2020 10:36 am
by IanMcCluskey
Moving this to the new AC Coupling forum, and adding a few sizing examples for reference.

We warranty up to 75% of the Radian(s) rating in AC Coupled inverter output.

Example 1 - GS4048A with twelve 250W micro inverters, or 3,000 W total
Example 2 - GS8048A with 1 6,000W grid dependent string inverter
Example 3 - Four GS8048A with three 7,600 W grid dependent inverters, or 22,800 W total