Power flow?

Discussion about adding energy storage to grid-dependent inverters using OutBack Power technology
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mhspohr
Forum Whiz
Posts: 27
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.

Power flow?

Post by mhspohr » Wed Jan 22, 2020 5:59 am

I'm not clear on power flow through/around Skybox given different power sources.
If you have AC solar connected to the Skybox load output, it would seem to me that this could push any arbitrary amount of power to the loads since this bypasses the Skybox. I assume that this will all go to satisfy loads first and then if there is excess power, it would be fed back to charge the batteries. If there is still too much power for the batteries, I assume that the Skybox would then manipulate the frequency to shut off the AC solar.
Is this correct?

Mike Curran
Forum Emperor
Posts: 1418
Joined: Sat Aug 28, 2004 6:28 pm
My RE system: Outback - Garage roof:
- 8 (2x4) Evergreen 180's into one FM80 (2007/2020 repl'd 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, no longer AC- coupled

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 from 14 Talesun 275W, Enphase M215 modules

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

Re: Power flow?

Post by Mike Curran » Wed Jan 22, 2020 6:16 am

I can't verify from personal experience, and I'm grid-tied so excess gets sold back, but your understanding sounds right to me. If I have a grid outage it will work exactly as you describe, theoretically anyway :smile: - Mike
http://www.tigoenergy.com/site.php?95b2dca2-ca6c
https://enlighten.enphaseenergy.com/public/systems/Hctc107221

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