Question about Solar + battery + grid

Cheap 4-life

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The topic of this thread is solar+battery+grid, I’m not so certain we destroyed the thread although we are getting deep into it.
As for antiislanding failing. I don’t see how that’s possible. Antiislanding means that the inverter cannot operate if grid power isn’t present. Grid tie inverters get their power to turn on from the grid, they can’t even be on without grid power being present.
I agree zero export isn’t needed for saving excess power into batteries. But it is also not just for people that don’t get paid to export. They might want to choose to not export due to not getting paid enough to export or not getting enough credit etc. Or in my case-area would have to spend a small fortune to have solar if they did export. Some people don’t have the money or know how or want to install an offgrid setup that is large enough to cover all of their homes usage. Yes they should still get the permits etc but sometimes like in my area they cost a lot. Imo my system is very safe and my system does not send anymore power back into the grid (when loads shutoff) than some motors sometimes do for a couple seconds.

Daromer your initial comment was that if the OP didn’t want to sell to the grid then they should have an offgrid system, which is generally the right way to think. I was mentioning grid tie with batteries or hybrid and zero export (legally done or not) so the option was there, that they don’t have to have a much more expensive offgrid setup that covers all of their loads-surges. Grid tied mode with or without Zero export is another way to implement solar+battery+grid. And if there’s no other option due to the extreme hoops-cost in some people’s areas they could choose to use grid tie or hybrid inverters with zero export. Although it might not be done legally, the electric company most likely would never know about it or care if you were not sending power past your meter. And as I explained above it can still be done safely;)
 
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Cheap 4-life

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This topic is interesting. I'd like to discuss mechanical UL listed ATSs (physically interlocked relays) vs 0 limiter systems. To me - a 0 limiter system (like this: https://www.ebay.com/itm/2241323088...1291&msclkid=6c6e115b173510f5d844719bcc111362 ) can be quite risky compared to a physically interlocked UL listed relay ATSs - because its a simple measurement and can easily measure 'wrongly'.... and allow power to out to the grid. On the other hand, physically interlocked relay ATS system seems a bit safer - because its physically (very unlikely/impossible) to send power to the grid unwittingly.

I'm not sure how hybrid (all-in-one/inverters) work but I assume they also use limiters? and therefore can be risky in the same way 0 limiters above - compared to mechanical ATSs as far as unwittingly allowing power to the grid?

I'd be interested in any comments on this.

Quick google search indicates that mechanical ATSs are legal in the U.S. - but may require electrician install in some jurisdictions.
Zero export-limiter is just as legal as an ATS. When I first started using zero export I made sure with a very accurate power monitor (I use Iotawatt) that power was not possibly being exported due to inaccurate measurements etc.
ATS has different functionality than a grid tie or hybrid limiter-zero export. ATS (as you know) are used to switch between grid-gen-offgrid. Ats is needed if offgrid and loads exceed the capabilities of the solar system. Where as grid ties keep operating at max output when loads exceed capabilities of the solar setup. Ats isn’t needed to switch to grid. Grid tie or hybrid keep running and allow loads to use excess grid power only when necessary. The zero export keeps power from being sold or fed past the meter similar to how an offgrid inverter works. Outback Radian in grid tie mode for example allows the grid to supply up to 1amp at 240v.
 
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not2bme

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I don't know about other grid-tied inverter hybrids, but my Schneider XW can limit the export to 0W. But what I've noticed is that even the total export is 0, the individual legs are not. The XW has a habit of 'balancing' the legs. So if one leg is taking 100W and another leg is taking 500W, there is an inbalance of 400W between the legs. What I see is an export of 200W of one leg, and an import of 200W on the other leg to balance the usage. The sum is 0W but the inverter is technically exporting on one leg if you're looking at just one phase.
 

Cheap 4-life

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I don't know about other grid-tied inverter hybrids, but my Schneider XW can limit the export to 0W. But what I've noticed is that even the total export is 0, the individual legs are not. The XW has a habit of 'balancing' the legs. So if one leg is taking 100W and another leg is taking 500W, there is an inbalance of 400W between the legs. What I see is an export of 200W of one leg, and an import of 200W on the other leg to balance the usage. The sum is 0W but the inverter is technically exporting on one leg if you're looking at just one phase.
My 240V GTIL2s do the same. 200w on one leg and 214w on the other to equal roughly 14w power still used. My Iotawatt uses 120v references from each leg, that’s why I see -200w and +200w. Most homes meters read our power usage with a 240v reference. They read the power used by a 240v sinewave. Inside the electric companies meter both of the legs go through one CT in opposite directions. So technically the backfeed is only happening if reading the power usage of each leg separately. Most meters put on our homes do not sense each leg separately.
 
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Cheap 4-life

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I don't know about other grid-tied inverter hybrids, but my Schneider XW can limit the export to 0W. But what I've noticed is that even the total export is 0, the individual legs are not. The XW has a habit of 'balancing' the legs. So if one leg is taking 100W and another leg is taking 500W, there is an inbalance of 400W between the legs. What I see is an export of 200W of one leg, and an import of 200W on the other leg to balance the usage. The sum is 0W but the inverter is technically exporting on one leg if you're looking at just one phase.
With the Schneider XW, are you using a watt node? From what I hear without the watt node the Schneider does still slightly feed past the meter. This is why my GTIL2s and Outbacks always allow the grid to supply some power to the loads. It gives the inverter some wiggle room-time to limit when loads change. It also just simply lets the grid supply some power so there’s not a chance it will end up backfeeding.
I’m asking because I’m still considering which inverter to get next
 
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Maarten

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The topic is getting rather technical but that is fine, the more info the better :)
'Antiislanding' is not really what I would desire, I still want to be able to use my power and systems when the grid stops working. I believe that is possible using the Vicron hardware, if I understand the information correctly.
Anyone any experience with that?
 

daromer

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Hybrid inverters also need permits if used with grid-tie enabled in the software. My inverter is Hybrid and it need the permit to be approved. Doesnt matter if i send back to the grid or not but its installed towards the grid.

Maarten: If you want to use your system when grid aint there and you want to do it legally a proper Hybrid system is the way to go where you have permission to install it.

I dont have experience with Victron though i wished i had but it was just to expensive so i went with MPP instead. Antiislanding is on all grid-tie systems and even hybrids. And on hybrids they use battery as main power. Victron can for sure do hybrid where you basically tell it when or how or how much to send to grid or not and use from battery/solar. And they are pretty efficient to :)
 

not2bme

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With the Schneider XW, are you using a watt node? From what I hear without the watt node the Schneider does still slightly feed past the meter. This is why my GTIL2s and Outbacks always allow the grid to supply some power to the loads. It gives the inverter some wiggle room-time to limit when loads change. It also just simply lets the grid supply some power so there’s not a chance it will end up backfeeding.
I’m asking because I’m still considering which inverter to get next

Not sure what a watt node is. I'm also using the old combox and not the newer gateway (that was almost 500 dollars which is just too high of a price to justify). I am not feeding it back through the grid yet. My goal is to use the modbus and have it match the utility meter at some point. But most of my usages are through the inverter itself so I haven't had a real need to backfeed. So even though it's in grid-tie mode I set it not to export and using the inverter side on the sub-panel. But even with that, it is technicaly tied to the grid so it's doing that balancing thing.

What I've found is that the XW isn't as low in power consumption as the specs say. When it's in grid-tie mode it consumes a lot more power. I wrote up a whole review of it but haven't posted it up yet. It's just a very complicated unit that has a million of options that really doesn't make sense or actually needed, and to this day I have a cheat sheet to make it work, but still don't quite understand it. It's as if it was built by one eccentric engineer that only programmed it the way he liked it, even though it makes no sense.
 
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