Critical load question

Dual Input, 120/240, stainless steel form factor design for unsurpassed surge capability
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rickd
Forum Member
Posts: 7
Joined: Mon Dec 23, 2019 6:12 pm

Critical load question

Post by rickd » Fri Oct 16, 2020 1:34 pm

I'm getting a GS8048A with battery backup and grid-tie, and have some questions about the load panels and when they are live and what is supplying the power.
1. If the grid/generator is down and the battery is charged, only the critical load panel is up, correct?
2. If the battery is flat and panels are not producing, and the grid/generator is up, will both panels be powered?
3. If the battery is charged and the grid/generator is up, will both panels be powered by both sources? E.g. non-critical panel has a load that the generator-only can't support, the inverter will assist.

Mike Curran
Forum Emperor
Posts: 1804
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: Critical load question

Post by Mike Curran » Fri Oct 16, 2020 2:52 pm

rickd wrote:
Fri Oct 16, 2020 1:34 pm
I'm getting a GS8048A with battery backup and grid-tie, and have some questions about the load panels and when they are live and what is supplying the power.
1. If the grid/generator is down and the battery is charged, only the critical load panel is up, correct?
Yes
rickd wrote:
Fri Oct 16, 2020 1:34 pm
2. If the battery is flat and panels are not producing, and the grid/generator is up, will both panels be powered?
Yes
rickd wrote:
Fri Oct 16, 2020 1:34 pm
3. If the battery is charged and the grid/generator is up, will both panels be powered by both sources? E.g. non-critical panel has a load that the generator-only can't support, the inverter will assist.
Yes, I believe in grid-tied mode according to this table from the Radian manual:
Screenshot_20201016-174930.jpg
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

fcwlp
Forum Czar
Posts: 542
Joined: Wed Jan 22, 2020 9:40 am
My RE system: GS8048A, FM80 w/3,600 W PV Fixed, FM80 w/2,700W on Zomeworks tracker, Mate3, 24 Trojan 2V L16 1100AH @ C20, Grid-Tied with Kohler 14RESA LPG Generator and MEP-803 Diesel if needed
I also install and maintain grid-tied and off-grid systems, details will be given for these system if required
Location: 80 miles NE of Phoenix at 5500'

Re: Critical load question

Post by fcwlp » Sat Oct 17, 2020 11:59 am

Mike, I am going to do a little clarification. The Radian has both a Grid input and a Generator input.
rickd wrote:
Fri Oct 16, 2020 1:34 pm
2. If the battery is flat and panels are not producing, and the grid/generator is up, will both panels be powered?
- If grid is up, both load panels are powered
- If grid is down and gen is up, only the critical loads panel is powered.
rickd wrote:
Fri Oct 16, 2020 1:34 pm
3. If the battery is charged and the grid/generator is up, will both panels be powered by both sources? E.g. non-critical panel has a load that the generator-only can't support, the inverter will assist.
Only one AC input (grid or gen) is used at a time.
- If grid is up, both load panels are powered
- if grid is down and gen is up, the generator pass-thru will assist the inverter with powering the critical loads panel.

Mike Curran
Forum Emperor
Posts: 1804
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: Critical load question

Post by Mike Curran » Sat Oct 17, 2020 3:22 pm

Thanks - Sorry to have given incorrect info. I totally overlooked the difference between how gen and grid inputs are used, even though my own system would behave exactly the same way as you describe, were I ever to use my generator.
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

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