Question about AC coupling

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Mike Curran
Forum Emperor
Posts: 1817
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC (2007)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input (manual switch during grid outage only) from 14 Talesun 275W,
Enphase M215 microinverters, normally direct grid tied

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Question about AC coupling

Post by Mike Curran » Sun Oct 06, 2019 8:10 am

I have a couple basic questions about how AC coupling works in a grid-tied system with a Skybox. I realize the Skybox does not at present allow for this but I understand that a future firmware update will permit it using frequency "dithering", just as Radian inverters are capable of now.

If an AC array is connected to the output of the Skybox when the grid is "up" and operating, does the excess (not being used in the critical loads panel) AC power flow through the Skybox to the grid? If so, when the grid is down does the Skybox open the connection so that no power from the AC array reaches the grid?

Thanks for any help answering these. - Mike
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

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BoMagluyan
OutBack Product Management
Posts: 33
Joined: Mon Mar 19, 2018 12:29 pm
My RE system: SkyBox
12x EnergyCell PLR batteries in an IBR3
no PV

Re: Question about AC coupling

Post by BoMagluyan » Mon Oct 07, 2019 9:37 am

Hi Mike,

Yes. AC Coupling for SkyBox is in beta testing now.

When an AC array is connected to the output of the Skybox and the grid is "up" and operating, the excess (not being used in the critical loads panel) AC power flows through the Skybox to the grid.

When the grid is down, the Skybox opens its grid connection so that no power from the AC array reaches the grid.
Bo Magluyan
OutBack Product Management

OutBack Power Technologies, Inc.
An Enersys Company
1628 W Williams Drive, Phoenix AZ 85027 USA
www.outbackpower.com

Mike Curran
Forum Emperor
Posts: 1817
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC (2007)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input (manual switch during grid outage only) from 14 Talesun 275W,
Enphase M215 microinverters, normally direct grid tied

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Question about AC coupling

Post by Mike Curran » Mon Oct 07, 2019 1:19 pm

Thanks, Bo. Please let us know when Skybox AC coupling goes "live". I'm installing one now and plan on connecting 2 AC arrays to the output, plus a DC string to the PV input. - Mike
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

mhspohr
Forum Whiz
Posts: 41
Joined: Sun Jun 30, 2019 8:56 am
My RE system: 6.6 kW SolarWorld/Enphase and 2.6 kW Sunpower/SMA
Skybox with 10 kWh SLA (used for power outage backup only)
Tesla 2015 Model S 85D charged from the sun.

Re: Question about AC coupling

Post by mhspohr » Wed Oct 23, 2019 8:51 am

I just ordered a Skybox. I have Enphase inverters. (Plan to add a DC string in the future. )
My Enphase inverters are connected to the grid at service entrance.
Can I connect the grid input of the Skybox to these Enphase inverters (behind grid disconnect) and have them feed the Skybox during grid outage?

Mike Curran
Forum Emperor
Posts: 1817
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC (2007)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input (manual switch during grid outage only) from 14 Talesun 275W,
Enphase M215 microinverters, normally direct grid tied

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Question about AC coupling

Post by Mike Curran » Wed Oct 23, 2019 1:09 pm

No. If there's a grid outage, the grid input to the Skybox is lost and the Enphase units will detect this and shut themselves down.

Once OB has released firmware to enable the Skybox to AC couple, you can connect your Enphase string to the Skybox AC output and (edit:)during a grid outage they will continue to operate, charging your battery through the the SB and supplying the loads on the AC out side of the Skybox. However, once your batteries are charged while operating in this mode, and your loads are satisfied, the SB will alter its AC output waveform to stop the Enphases from continuing to operate (they will sense the irregular waveform and shutdown). This prevents overcharging your battery from the Enphase string.

Hope this makes sense. - Mike

Edited to clarify AC coupling operation during a grid outage.
Last edited by Mike Curran on Thu Oct 24, 2019 4:42 pm, edited 1 time in total.
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

mhspohr
Forum Whiz
Posts: 41
Joined: Sun Jun 30, 2019 8:56 am
My RE system: 6.6 kW SolarWorld/Enphase and 2.6 kW Sunpower/SMA
Skybox with 10 kWh SLA (used for power outage backup only)
Tesla 2015 Model S 85D charged from the sun.

Re: Question about AC coupling

Post by mhspohr » Wed Oct 23, 2019 1:21 pm

Great!
Thanks for this information. I understand now.

mhspohr
Forum Whiz
Posts: 41
Joined: Sun Jun 30, 2019 8:56 am
My RE system: 6.6 kW SolarWorld/Enphase and 2.6 kW Sunpower/SMA
Skybox with 10 kWh SLA (used for power outage backup only)
Tesla 2015 Model S 85D charged from the sun.

Re: Question about AC coupling

Post by mhspohr » Sun Oct 27, 2019 8:45 am

BoMagluyan wrote:
Mon Oct 07, 2019 9:37 am
Hi Mike,

Yes. AC Coupling for SkyBox is in beta testing now.

When an AC array is connected to the output of the Skybox and the grid is "up" and operating, the excess (not being used in the critical loads panel) AC power flows through the Skybox to the grid.

When the grid is down, the Skybox opens its grid connection so that no power from the AC array reaches the grid.
So, if I'm reading this correctly, the Skybox will feed AC solar connected to the load output back to the grid input if there is excess and the grid is up.

(Just bought a Skybox and most convenient would be to hook my 2.8 kW AC Enphase array to it. Looking forward to the AC coupling feature.)

DrewS
Forum Junior Member
Posts: 3
Joined: Mon Dec 09, 2019 9:09 pm
My RE system: System at issue: Stacked Skyboxes with SimpliPhi batteries and a hybrid DC and Emphase IQ7 panels

Re: Question about AC coupling

Post by DrewS » Wed Dec 11, 2019 5:46 pm

In case you have not updated, AC Coupling is in the current release and works great.

Unfortunately, it's not operational for stacked Skyboxes.

Outback, any idea of when we will see AC Coupling on stacked Skyboxes???

thanks,
Drew

User avatar
BoMagluyan
OutBack Product Management
Posts: 33
Joined: Mon Mar 19, 2018 12:29 pm
My RE system: SkyBox
12x EnergyCell PLR batteries in an IBR3
no PV

Re: Question about AC coupling

Post by BoMagluyan » Wed Dec 11, 2019 6:05 pm

@DrewS wrote ... Outback, any idea of when we will see AC Coupling on stacked Skyboxes???
I don't know when or if we will see AC Coupling and stacking. It looks like it might be difficult.
We have our next major firmware release in the development queue for early 2020. Maybe before March. There are more than a few exciting features in that release. But not AC Coupling and stacking.
@DrewS wrote ... In case you have not updated, AC Coupling is in the current release and works great.
Yay! That's wonderful to hear. Thank you.
Feel free to post photos and specs if you want us to write up a case study and share it with the community. And please give us any positive, negative, or 'please make this different' feedback.
Bo Magluyan
OutBack Product Management

OutBack Power Technologies, Inc.
An Enersys Company
1628 W Williams Drive, Phoenix AZ 85027 USA
www.outbackpower.com

Mike Curran
Forum Emperor
Posts: 1817
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC (2007)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input (manual switch during grid outage only) from 14 Talesun 275W,
Enphase M215 microinverters, normally direct grid tied

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Question about AC coupling

Post by Mike Curran » Thu Dec 12, 2019 4:33 am

@DrewS - Thanks, didn't know the latest firmware incorporates AC coupling. I'm going to switch my arrays over today. Good news! - Mike
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

mhspohr
Forum Whiz
Posts: 41
Joined: Sun Jun 30, 2019 8:56 am
My RE system: 6.6 kW SolarWorld/Enphase and 2.6 kW Sunpower/SMA
Skybox with 10 kWh SLA (used for power outage backup only)
Tesla 2015 Model S 85D charged from the sun.

Re: Question about AC coupling

Post by mhspohr » Thu Dec 12, 2019 6:06 am

Great news. I'll update ASAP

Ampster
Forum Guru
Posts: 119
Joined: Sat Apr 11, 2015 5:14 pm
My RE system: 5.7K solar system with Solaredge inverter. Heat pump water heater.
28 kWh pack of LFP batteries powering a Skybox which is used for load shifting and backup.
Location: Sonoma, Northern California

Re: Question about AC coupling

Post by Ampster » Mon Aug 10, 2020 2:16 pm

I have been AC coupling 4 Enphase inverters through my critical loads panel and it works great.
I now want to move my Solaredge inverter over to the critical loads panel but I am tight on breaker space. I have heard you can run it through the generator input but I don't see any settings for that. The solaredge inverter is 3.8kW and the Enphase micros total less than 1kW. I have 28 kWh of batteries so I have plenty of buffer.

Anybody AC couple through the Generator in port of the Skybox?
Drive Tesla Model X and Model 3 which are charged at Super Off Peak rates.

Mike Curran
Forum Emperor
Posts: 1817
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 - replaced MX60)
- 6 (2×3) ALEO S79-300's into one FM80 (2017)
- 2 grid-tied GVFX3524's classic stacked for 120/240VAC (2007)
- 12 Surrette/Rolls 2V x 1766Ah (2007)
- Hub10.3, Mate3s, FNDC, RTS, OpticsRE. Tigo Energy ES maximizers on each PV module.

Westinghouse Solar - Barn roof: (2012)
- 30 (2x15) 235W panels with Enphase M215 microinverters, grid-tied

Outback Skybox - Barn roof: (2019)
- 14 Talesun 275W in series (DC array input to SB inverter/charger)
- 3 SimpliPhi 3.8 batteries, 48V, 225Ah total
- AC coupled input (manual switch during grid outage only) from 14 Talesun 275W,
Enphase M215 microinverters, normally direct grid tied

All self-designed and self-installed
Location: Chagrin Falls, Ohio

Re: Question about AC coupling

Post by Mike Curran » Mon Aug 10, 2020 3:04 pm

Anybody AC couple through the Generator in port of the Skybox?
The AC coupling connection must be made to the output of the inverter, where your grid-tied inverters will find the 120 volts AC they need to stay connected. It will not work if connected to any inverter input.
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

User avatar
Greg T Fordan
OutBack Technical Service
Posts: 369
Joined: Fri Dec 29, 2017 1:56 pm
My RE system: Radian, FM80, FNDC, 48V batt bank

Re: Question about AC coupling

Post by Greg T Fordan » Mon Aug 10, 2020 3:17 pm

Ampster wrote:
Mon Aug 10, 2020 2:16 pm
xxx I have heard you can run it through the generator input but I don't see any settings for that. xxxxx

Anybody AC couple through the Generator in port of the Skybox?

It is INCORRECT to connect a battery less grid-tie inverter to the Generator port just as INCORRECT to connect it to the Grid port.

It must be connected to the Skybox output, which is what you presently have now when you connect it the critical loads panel.

And for added info, there is an "interlock" between the Grid port relay and Generator port relay. Only one can be energized at any time.
Greg T Fordan
EngTech
Outback Power Technologies

Ampster
Forum Guru
Posts: 119
Joined: Sat Apr 11, 2015 5:14 pm
My RE system: 5.7K solar system with Solaredge inverter. Heat pump water heater.
28 kWh pack of LFP batteries powering a Skybox which is used for load shifting and backup.
Location: Sonoma, Northern California

Re: Question about AC coupling

Post by Ampster » Mon Aug 10, 2020 3:59 pm

Okay, I disconnected my EV charger breaker which is on the critical loads panel (Inverter Out) and got it working through that.
I don't know why I thought I could do it through the generator port. Something about it being bidirectional in some Webinar, but that is why I asked because I could not find it documented.
I upgraded my pack and I want to try Self Consumption but I did not have enough solar on the Skybox to get a full charge after running the house all the time. Now I can use that GT inverter to charge my new pack and still sell some back to the grid when the pack is full and my house loads are met. After two years I think I can start getting the full benefit of my system. No fault of Outback. My original pack was not big enough and swinging the GT inverter to be AC coupled was the last piece of the puzzle.

We are heading into fire season and I am now ready for a three day outage like we had last year.

Thanks both of you for your quick response.
Drive Tesla Model X and Model 3 which are charged at Super Off Peak rates.

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