Need an advice to select GS4048 or GS8048

Discussion about adding energy storage to grid-dependent inverters using OutBack Power technology
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mkimid
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Posts: 3
Joined: Tue Nov 19, 2019 3:33 pm
My RE system: GS4048A AC Coupling

Need an advice to select GS4048 or GS8048

Post by mkimid » Tue Nov 19, 2019 3:46 pm

Hi,

I have a plan to add an AC coupled back-up on my GTI system.
I have installed sub-panel (for essential power), the peak load usage should be 0.1~3kW
and, I have 320W(OTI inverter output) x 16 panel = ~5kW

for the back-up system, I have expected that GS4048 is more than enough for me when consider my essential power load,
But, I found two issues

(1) if the load is used in a hot line, such as only one line L1 or L2, maybe inverter output power is going HALF as 2kW. is it correct ?
I found, 16.7AAC is a maximum continuous power, 16.7AAC * 120V = ~2kW

(2) Even I made a good balance, I found 2nd problem. the maximum utility interactive current is 15A (3.1kW).
GRID is ON, and PV generate ~5kW in peak, Maybe GS4048 can not sell whole current.
or Can sell UPTO 50A (limit of bypass relay contact rate) ?

AC coupled system cost with GS4048 is ~$3k, and GS8048 is ~6k. It is too big difference even I need < 3kW essential power load for backup

Could you give me an advice about it ?

EMCF
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Posts: 96
Joined: Thu Jul 21, 2016 10:22 am
My RE system: FX3048, 4 200a batteries, FM60. 3 kw array

Re: Need an advice to select GS4048 or GS8048

Post by EMCF » Tue Nov 19, 2019 4:40 pm

What is the brand of your GT inverter? One thing you need to ask around is if your kind of GT inverter plays well with a Radian(GS) inverter. The other thing is, one of the requirements is the Outback inverter must be of higher capacity than the GT inverter. In their application note example,Radian GS8048A rated at 8kW was paired (AC Coupled) with a 6 kW grid tie inverter. You should comply with the ratio along that example.
Outback Fanboy at your service

Mike Curran
Forum Emperor
Posts: 1751
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 (2x7) Talesun 275W (DC array input to SB 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: Need an advice to select GS4048 or GS8048

Post by Mike Curran » Tue Nov 19, 2019 4:53 pm

Looking at the gs4048/8048 manual, it appears you're right about the max power output from either L1 or L2:
Screenshot_20191119-192815.jpg
As far as max PV input from an AC - coupled array, per OB's app note on AC coupling, it looks like it's 6kw:
Screenshot_20191119-194232.jpg
Here's links to the pertinent documents: http://outbackpower.com/downloads/docum ... p_note.pdf

http://outbackpower.com/downloads/docum ... erator.pdf
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

mkimid
Forum Junior Member
Posts: 3
Joined: Tue Nov 19, 2019 3:33 pm
My RE system: GS4048A AC Coupling

Re: Need an advice to select GS4048 or GS8048

Post by mkimid » Wed Nov 20, 2019 9:53 am

EMCF wrote:
Tue Nov 19, 2019 4:40 pm
What is the brand of your GT inverter? One thing you need to ask around is if your kind of GT inverter plays well with a Radian(GS) inverter. The other thing is, one of the requirements is the Outback inverter must be of higher capacity than the GT inverter. In their application note example,Radian GS8048A rated at 8kW was paired (AC Coupled) with a 6 kW grid tie inverter. You should comply with the ratio along that example.
I have installed SunPower X21-350-D-AC panels (I feel it is enphase ODM, but maybe Subpower own band),
16 x 320W (maximum inverter power) = 5.12kW, Practically little under 5kW in my measurements.

It has connected on essential power panel, my essential power usage is peak ~3kW, general usage 1~2kW, and < 0.1kW most of time.

Thank you for your advice,

mkimid
Forum Junior Member
Posts: 3
Joined: Tue Nov 19, 2019 3:33 pm
My RE system: GS4048A AC Coupling

Re: Need an advice to select GS4048 or GS8048

Post by mkimid » Wed Nov 20, 2019 9:58 am

Mike Curran wrote:
Tue Nov 19, 2019 4:53 pm
Looking at the gs4048/8048 manual, it appears you're right about the max power output from either L1 or L2:Screenshot_20191119-192815.jpgAs far as max PV input from an AC - coupled array, per OB's app note on AC coupling, it looks like it's 6kw:Screenshot_20191119-194232.jpg
Here's links to the pertinent documents: http://outbackpower.com/downloads/docum ... p_note.pdf

http://outbackpower.com/downloads/docum ... erator.pdf
I feel, practical spec for 4048/8048

GTI 3kW 6kW
Line Power 2kW 4kW

Maybe, I have to find the other method even a manual connections,
but, it is hard to find a battery charger which can charge the battery from GTI Solar Power Source [unstable],
do you have any idea ?

Mike Curran
Forum Emperor
Posts: 1751
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 (2x7) Talesun 275W (DC array input to SB 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: Need an advice to select GS4048 or GS8048

Post by Mike Curran » Wed Nov 20, 2019 11:42 am

it is hard to find a battery charger which can charge the battery from GTI Solar Power Source [unstable]
So, you're saying your grid-tie AC modules are so "unstable" that the OB inverter won't invert it to charge your battery? How big is the battery, amphours? FWIW, unless there's some problem with your AC modules' output, seems like a 4048 would be perfectly adequate for you.

Edit: My impression from the app note is that both the 4048 and the 8048 will accept up to 6kw of AC coupled input, since the note only refers to the Radian and not to a particular variant of it.
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

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IanMcCluskey
OutBack Product Management
Posts: 154
Joined: Tue Aug 28, 2018 1:16 pm

Re: Need an advice to select GS4048 or GS8048

Post by IanMcCluskey » Mon Jan 20, 2020 10:34 am

I am moving all threads related to AC Coupling to the new AC Coupling forum, and I notice the last post on here is incorrect.

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
Ian McCluskey
Product Manager


Alpha Technologies Inc. / OutBack Power Technologies
3767 Alpha Way Bellingham WA 98226 USA
http://www.alpha.com

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