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Question About Preventing Grid Backfeed

zanydroid said:
Parallel means the grid AC and the inverter output AC touch directly.

This can happen with systems that don't blend, too, EG active standby.

The relay/contactor stuff people talk about refers to systems where the outputs are air gapped by some sort of isolation. For instance, an inverter in UPS mode can be pre-synchronized to grid (by letting the inverter "see" the waveform via voltage sensors), but the inverter can be kept disconnected from the output while the output is connected to grid.
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I understand what you are saying. I guess what I'm getting at is can I blend with an off grid inverter without the risk of backfeeding like with a hybrid.
You and I are both PG&E so you can understand why I'm trying to avoid dealing with them as much as possible.
 
jeff88 said:
You and I are both PG&E so you can understand why I'm trying to avoid dealing with them as much as possible.
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PG&E isn’t that bad. The red tape is easy because there is a huge volume of projects being installed in the territory so you can easily find answers and outsource CAD work, etc for permit ready planset

The main issue is the UL9540 cost. If you have good site conditions your ROI can still be acceptable under NEM3 esp with DIY discount. Have you asked for a turnkey estimate? You can get stuff like Aurora Shade report to see what conditions you have, as well as an ROI calculation. From which you can divide by 2 and see what your DIY ROI will be.
 
Also if you live in a city above the population cutoff, you have access already to streamlined permitting via SolarApp+. And if below the cutoff the mandatory date for adoption is this September
 
cs1234 said:
If I want to put some batteries in my garage, I shouldn't have to put huge concrete / metal pillars into the floor to keep a car from running into them.. that's asinine.
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There needs to be some sort of carproof protection. Crush testing is often used as a way to start a battery fire, to observe how they burn and how the fire propagates.
If you think about it, we wouldn't even have electricity, or telephones, or any other number of modern technologies if we had all these rules and regulations in the first place.
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Right. They get put in later. For solar, it's "later."
 
ChrisG said:
Neighbor hooked up a Solark and POCO swung by the same day and made him disconnect.
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Can confirm that my Deye (maker of Solark) also exports small amounts by default in both zero export mode.
 
ChrisG said:
Only actual evidence I have that the 6000xp I have doesn’t send anything back to grid is: Neighbor hooked up a Solark and POCO swung by the same day and made him disconnect. My XP has been running for months without incident.
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Is your 6000XP connected to the grid?
 
ChrisG said:
Sure is. No panels attached at the moment but handles the grid down issues no problem which happens frequently as seen in the second picture. 10kwh DIY battery attached.
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So is an 6000XP an alternative to double conversion if you want to 100% prevent all exporting to grid?
 
Last edited:
kolek said:
So is an 6000XP an alternative to double conversion if you want to 100% prevent all exporting to grid?
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I can’t say for sure but the POCO has never contacted me about it. They caught my neighbor in just a few hours with his Solark.
 
kolek said:
Tim maybe this is obvious but you decided to have things setup that way to avoid trouble with your PoCo? Essentially you're doing double conversion?
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Not really an issue with POCO. Just don't want any connection to the grid,
unless it is isolated.
Yes, double conversion by choice.
Also future plans are for multiple sources to charge from, or use as backup.
(Generators, EV's, grid, or whatever else I can dream up)
 
ChrisG said:
How does one do this out of curiosity.
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Now that I re-read the post, it looks like it would be difficult.
diysolarforum.com

Luxpower tek important US users press release includes EG4 6000XP

This was released on X the other day and I asked LUXPOWER if this included the EG4 6000xp. They confirm it does. Not sure what it means to most of us but sounds like they are emphasizing not to connect to the grid with these inverters. Am I reading this wrong? Thoughts folks.
diysolarforum.com diysolarforum.com
 
I'm confused about this double conversion thing. Are you guys saying that the inverter will blend self gen power with grid power and not have the ability to backfeed? Does the double conversion not convert the other way so it can't send power back?
 
jeff88 said:
I'm confused about this double conversion thing. Are you guys saying that the inverter will blend self gen power with grid power and not have the ability to backfeed? Does the double conversion not convert the other way so it can't send power back?
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Correct
Double conversion just means that the only connection to grid is through a battery charger.
 
In my case.
When my battery bank falls to 48v, the charger kicks in and covers whatever loads it needs to, in order to keep the bank from going any lower.
 
jeff88 said:
I'm confused about this double conversion thing. Are you guys saying that the inverter will blend self gen power with grid power and not have the ability to backfeed? Does the double conversion not convert the other way so it can't send power back?
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Yes. It is AC to DC to AC conversion.

Grid -> AC -> Battery Charger -> DC -> Inverter -> AC -> Loads

It's less efficient, in that you have losses converting the AC to DC and back again to AC.. but it doesn't have any risk of feedback.. and you can run as many chargers as you want from different sources.. say a generator, or a car with inverter on it, etc..

Whatever inverter you have hooked up to the charger, it treats the output from the charger no different than it does incoming current from the battery.. it's just DC current to it.
 
jeff88 said:
I'm confused about this double conversion thing. Are you guys saying that the inverter will blend self gen power with grid power and not have the ability to backfeed? Does the double conversion not convert the other way so it can't send power back?
Click to expand...
There is no blending of grid power when using a battery charger (chargeverter is a battery charger) hooked to the grid and charging your battery. Using the grid through your AIO in certain ways can have the inverter operating in parallel with grid (blend-your word). Double conversion is just a fancy description for using a separate battery charger to keep your setup operating off the inverter with no AC input.
 
jeff88 said:
I'm confused about this double conversion thing. Are you guys saying that the inverter will blend self gen power with grid power and not have the ability to backfeed? Does the double conversion not convert the other way so it can't send power back?
Click to expand...
I don’t think there is an AIO with double conversion. It requires an external box like a Chargeverter.

One stage of double conversion is a ac/dc charger/power supply. This is unidirectional except for random leakage (and it is acceptable since same can happen for any power supply. Well, ok if we want to go down the rabbit hole the POCO can complain about injection of bad power quality from stuff plugged into the grid but typically won’t do this for a residence).

There is no blending with grid because of the DC step in the middle
 
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