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Utility company visited me for exporting from my solar Off-grid growatt LVM-ES SPF 3000TL

SeaGal said:
OK, but if you have a grid-tied inverter it will accidentally export when a large load is turned off. As @ricardocello demonstrated in his graph above. The limitation is down to how quickly the inverter will respond to a change in load. From my experience, the speed of response also differs depending on whether it was powering the load from PV or battery.

Fortunately it's not an issue for us in the UK as everyone is permitted to export up to 16A (3.6kW), provided that the DNO has been informed and you are using approved / tested equipment.
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Ma'am, that would make entirely too much sense for the US to adopt that, not to mention the fact that the power companies are money hungry scumbags.
 
Mattb4 said:
Hmmm... I will have to think about this for a bit. My first assumption is that export would be much more likely during low household demand.
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Accidental exporting happens when a large load shuts off, and the inverter can't react fast enough to control the export.
With minimal loads running, it's not an issue. Because there isn't a large load that can shut off.
 
SeaGal said:
if you have a grid-tied inverter it will accidentally export when a large load is turned off
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My tests indicate that with a 200W draw, my Deye is no longer exporting when switching off large loads (if my measurement method is accurate)
 
Norwasian said:
A good friend of mine, in America, worked as a lineman, and had stories to tell of colleagues who were linemen. They often do their work, intentionally, with live lines. They know very well what they are doing, and must take proper precautions to avoid electrocution. If they can work on live lines which have hundreds of thousands of volts, why should they fear to work, taking similar precautions, on a supposedly dead line that has some residual voltage in the 120-220v range?
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doesnt that 120v backfeed from your house get stepped up by the transformer to thousands of volts?
 
Norwasian said:
A good friend of mine, in America, worked as a lineman, and had stories to tell of colleagues who were linemen. They often do their work, intentionally, with live lines. They know very well what they are doing, and must take proper precautions to avoid electrocution. If they can work on live lines which have hundreds of thousands of volts, why should they fear to work, taking similar precautions, on a supposedly dead line that has some residual voltage in the 120-220v range?
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Tell me you don't understand how the grid works, without telling me you don't understand how the grid works. The lines the linemen work on would never have 120-220V on them. Inverter voltage runs out to the transformer and gets stepped up to whatever the line runs at...
 
kolek said:
Definitely a concern. Have you tried what @Crowz and I are trying with your Victron ESS and seen if that addresses the feedback? By that I mean, pulling 200W either thru the inverter via settings or putting a load between the inverter and the grid to continuously suppress backfeed?
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The problem is, even with a setting like that, a really large load, like an air conditioner will always cause a blip if it's being offset by the inverter.

The only way to really prevent backfeed is to limit what your inverter is covering to your sustained loads.

For example: If you have a bunch of stand alone air filters, and you run them all the time, and they use 500watts consistently (never wavering). You can cover those 500 watts with your grid synced inverter / GTIL. However, if they turn off, you're gonna export.

If you cover something that goes up and down and all around, like an air conditioner, you are covering it on startup and when it's running without export, but as soon as it drops off, you are going to spuriously export. The synced inverters / GTIL simply can't react fast enough to cover any loads that drop off rapidly.. or really any loads that drop off at all. It has to be something that is ALWAYS on, and you can only cover whatever it's smallest base load is.

It doesn't matter if you have your inverter set to 200-500 watts of always pull from grid. Those big loads being covered are just going to power through that like a hot knife through butter for a brief period of time.

Double conversion is really the only way to do it with anything approaching a guarantee. Which sucks, because it's wasteful to double convert. Unfortunately, the most affordable prebuilt 48v high amperage charger is the EG4 Chargeverter. The product itself is pretty good, but some people aren't big fans of EG4/Signature Solar.
 
SparkyJJO said:
The "you'll kill a lineman" argument falls on its face because the only time the inverter is backfeeding any is when the grid is up and live anyway!
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LOL, narrow scope. The lineman does not know what or where the source of the power is coming from when the power is not coming from the expected direction.

Seems to me no back feed is the goal and because the inverter(s) is not achieving the goal...rationalizing enters. What's the harm of a little back feed?

And finally, I will drop the subject, the power lines are not my or your property. The owner of the power lines sets the requirements. If you owned the power lines you would want the same consideration.

<soap box off>
 
cs1234 said:
you can only cover whatever it's smallest base load is.
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I wonder about that. I'm not disagreeing with you, but in my tests, switching off a 1000W load was generating a short 340 watt export, then when I added 100 watts draw, it reduced that 340W export to only a 30W export, and a 200W setting reduced the export to zero. Again I need to point out my testing method is hardly "scientific," I'm just looking at my inverter display when we switch these appliances, which may be a very different reading then a smart meter designed to pick up these signals.
 
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Mark- said:
LOL, narrow scope. The lineman does not know what or where the source of the power is coming from when the power is not coming from the expected direction.

Seems to me no back feed is the goal and because the inverter(s) is not achieving the goal...rationalizing enters. What's the harm of a little back feed?

And finally, I will drop the subject, the power lines are not my or your property. The owner of the power lines sets the requirements. If you owned the power lines you would want the same consideration.

<soap box off>
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If you look at what's been said, the only time this is an issue is when the inverter is in a particular mode setting (SUB). If the U goes down, it isn't even touching it anymore because it can't use that as a source. So now the backfeed is a non-issue. Any "excess" solar production at that point when a load is switched off just goes back into the battery.

If you want to talk about ownership of lines and stuff then fine, but don't use the "you'll kill somebody" argument then move the goalposts when that doesn't hold water. Just talk about the ownership and leave it at that.
 
SparkyJJO said:
If you look at what's been said, the only time this is an issue is when the inverter is in a particular mode setting (SUB). If the U goes down, it isn't even touching it anymore because it can't use that as a source. So now the backfeed is a non-issue. Any "excess" solar production at that point when a load is switched off just goes back into the battery.

If you want to talk about ownership of lines and stuff then fine, but don't use the "you'll kill somebody" argument then move the goalposts when that doesn't hold water. Just talk about the ownership and leave it at that.
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#1 OK, I did not move the goal post; the issue changed from no back feed to a bit is OK and I opine that is not OK and gave additional reasons.
#2 The issue is back feed, the source is not relevant.

>What is "the expected direction" of AC?

What? You think because AC cycles it does not have a power flow direction?
 
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I ran my 120V critical loads sub panel in SUB mode (no batteries then) for about 8 months last year, and this was also when the Poco came out and changed my meter. I'm sure the tech saw my array in the yard while he changed out the meter, but he didn't ask any questions nor did I offer any info. Anyways I never got a visit from them then telling me I was back feeding.

If I am feeding this sub panel from my inverter (EG4 6500) only, should I be worried about any back feeding?

Since I added a second 5kwh battery in March, we have been pretty much off-grid (and SBU mode) since then. I still have the grid hooked into the inverter input, but really haven't used the grid since we added the second battery. So, I probably should just shut off the AC input breaker on the service pole panel..
 
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kolek said:
How did you test? I need a better way of testing.
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My load is on the wrong side. You need something to sink the current into on the grid side. I misunderstood what was being said as my load is on the load side. It makes sense if you think about it.
 
kolek said:
I wonder about that. I'm not disagreeing with you, but in my tests, switching off a 1000W load was generating a short 340 watt export, then when I added 100 watts draw, it reduced that 340W export to only a 30W export, and a 200W setting reduced the export to zero. Again I need to point out my testing method is hardly "scientific," I'm just looking at my inverter display when we switch these appliances, which may be a very different reading then a smart meter designed to pick up these signals.
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I don't disagree that it helps reduce the backfeed. But reducing is not eliminating. The power companies are complaining about 1watt for a fraction of second in some of these stories. Throw a bigger device on there, like an 3 ton air conditioner.. and 200watts probably won't help.
 
cs1234 said:
I don't disagree that it helps reduce the backfeed. But reducing is not eliminating. The power companies are complaining about 1watt for a fraction of second in some of these stories. Throw a bigger device on there, like an 3 ton air conditioner.. and 200watts probably won't help.
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You very well may be right. I'm just testing and hoping for a solution short of doing double conversion.
 
LOL, narrow scope. The lineman does not know what or where the source of the power is coming from when the power is not coming from the expected direction.

Seems to me no back feed is the goal and because the inverter(s) is not achieving the goal...rationalizing enters. What's the harm of a little back feed?
Click to expand...

The backfeed only occurs when the power is working and the inverter is able to sync up to the grid. Once power goes down, so does the backfeed. The only reason 100% no backfeed is the goal, is to keep the power company from noticing you are generating some of your own power against the rules. It's not to save linemen, who aren't in any danger in the first place.. other than perhaps for the tiniest second or two before the inverter drops off because there is no AC coming in from the grid. I have a hard time believing the lineman have that fast of a response time to downed power conditions.

Mark- said:
And finally, I will drop the subject, the power lines are not my or your property. The owner of the power lines sets the requirements. If you owned the power lines you would want the same consideration.
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Do you feel that the power companies, as government approved monopolies deserve the exact same property rights as a truly private company/individual that doesn't receive subsidies / monopoly provisions?
 
kscessnadriver said:
Tell me you don't understand how the grid works, without telling me you don't understand how the grid works. The lines the linemen work on would never have 120-220V on them. Inverter voltage runs out to the transformer and gets stepped up to whatever the line runs at...
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I didn't say I was a lineman. I won't claim to have special knowledge in that department myself, but I did enjoy my friend's stories, such as the one where linemen were killed while working on 600,000 volt lines when their boom truck somehow moved unexpectedly and became a conductor, earthing some serious amperage. The men in the truck attempted escape, but at least one of them, while shuffling away from the truck through the pools of electrical current, stumbled. The voltage potential between his feet and his head when it reached the ground was more than enough to cause his instant demise.

I've often heard it said that it's the amps that kill you, not the volts. By the time you convert 5 kw of 220v current up to 600,000 volts, how many amps would you have left?

In any case, it's my understanding that this "backfeeding" only occurs when the lines are live, because if the grid shuts down, so does the inverter--and it cannot backfeed if it isn't producing. The brief moment just after the lines have gone down and when backfeed may still be occurring is not likely the moment that the linemen are already working on it--and if it was, then they were fully expecting live lines already.
 
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Mark- said:
The owner of the power lines sets the requirements.
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Since you seem to speaking for the utility companies, can you please cite one case where the power company or someone working for the power company was injured by backfeed that occurred when the grid was up as a result of a homeowner solar install backfeeding to grid? I'm not aware of any, and I don't understand how backfeeding small amounts of power to the grid when the grid is up hurts anyone or anything. To me it seems utility companies are just looking for ways to protect their business interests and safety has nothing to do with this.
 
cs1234 said:
Double conversion is really the only way to do it with anything approaching a guarantee. Which sucks, because it's wasteful to double convert. Unfortunately, the most affordable prebuilt 48v high amperage charger is the EG4 Chargeverter. The product itself is pretty good, but some people aren't big fans of EG4/Signature Solar.
Click to expand...
I use the HEP-2300-55 and yes it's 4x the cost of the chargeverter per kilowatt but you get:

95% Efficiency

Fanless!

Up to 55kWh per day

Native two wire control support for on off signaling by dry contact relay
 
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