Darren Orange
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I just came across this video. Does this actually work?
Reverse feeding a inverter?
- Thread starter Darren Orange
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sunshine_eggo
Happy Breffast!
This is simply AC coupling a grid tie system to an off grid system. Very common for folks that want to actually have power when their grid goes down. Here's another video that popped up at the end of the video you linked (RIP Amy):
It has limited utility to a grid tie system as you won't get any more AC power available as the AC power is still limited by the off-grid inverter's output.
This is the guy in the video you posted:
@HighTechLab
It has limited utility to a grid tie system as you won't get any more AC power available as the AC power is still limited by the off-grid inverter's output.
This is the guy in the video you posted:
@HighTechLab
HighTechLab
AKA Dexter - CTO of Current Connected, LLC
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Hello!
OzSolar
Whatever you did, that's what you planned.
I've done AC coupling with SMA's system but never mixed and matched brands because its such a head scratcher for me. My little brain tells me to stop before I blow something up.
Does anyone know if you can AC couple the wth old Trace SW Inverters? I actually have a dual stack of SW4048 of them and might just have try it someday.
Darren Orange
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Hey!
So I watched your video, great work by the way. I'm trying to understand does it mater? Do all inverters work this way? Also if the batteries have a BMS it would stop the charging from hurting the batteries but would bad stuff happen with the grid tided inverters?
sunshine_eggo
Happy Breffast!
Page 83 discusses grid interaction modes/methods:
I don't believe it has the "phase shifting" or battery charging options.
HighTechLab
AKA Dexter - CTO of Current Connected, LLC
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BMS would cut off but the bus voltage would continue to rise, until the inverter trips out on HVD and the ac shuts down. It would be a swingset effect.
OzSolar
Whatever you did, that's what you planned.
It certainly does not. Thank you very much for digging into that and replying!!
Obviously it's not "built in" but I still think there's a way to do it. Albeit a very clumsy way. Ha. I need to watch the video you shared from Amy a few more times because she did lay it out pretty well. Specifically where mentioned the ratio of the array sizing vs the battery based inverter.
I have four 3 kW strings (~12 kW total) on a 10 kW string inverter tied into to my main 200 AMP breaker box.
Additionally I have ~70kWh of 2v FLA batteries tied to a 8kW worth of Trace SW inverters stacked in a split phase 120/240v configuration. That system is backing up most of my house.
What I think I got from Amy's commentary is that as long as my batteries aren't fully charged and I'm not over the KW rating of the Trace's I can AC couple. Since this would just be for emergencies probably what would happen is I would disconnect two of the strings on the string inverter and then get the AC of the string inverter wired directly to the Trace's. I think where things will get silly is when my batteries get full and there's no where to put the KW's from the string inverters.
Then again I've got a 14 kW Kohler generator so I'll probably just start it after 2 to 5 days when my 70kWh's of batteries get depleted.
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