Any thoughts on this problem? I just can't win

[Salts]

2ga for 32 amps at 180feet seems fine. I was thinking it was a single feed line for both inverters which would push up the voltage drop.

Have you considered switching the inverters around? Change places and see which one trips?

Going to try one more suggestion but it might seem silly. Have you gone into the inverter's configuration menu and made sure they have the same settings? Maybe the one that is tripping has its grid parameters set tighter than the other one?

[Markyrocks69]

2ga for 32 amps at 180feet seems fine. I was thinking it was a single feed line for both inverters which would push up the voltage drop.

Have you considered switching the inverters around? Change places and see which one trips?

Going to try one more suggestion but it might seem silly. Have you gone into the inverter's configuration menu and made sure they have the same settings? Maybe the one that is tripping has its grid parameters set tighter than the other one?

Switching the inverters around seems like a tremendous amount of work just to for a test. Yes I have checked all the settings to see if they're the same. They look the same to me. With the sma inverters it doesn't allow me to change settings related to the ac voltage parameters ect. I would need to obtain a grid guard code from sma to do that. Setting one inverter a little higher might fix the issue but idk if I'm going to be able to get a grid guard code.

As an update I changed the wiring around a bit to see if it fixes anything. Doesn't seem like it has. It's just weird bc when one inverter is pumping out its maximum the output hovers around 255v. I just checked the voltage in the panel and it says its around 251-253v it kinda steadily fluctuates between the 2 values. So as you can see the voltage drop is relatively small. Now what is stopping the other inverter from operating in the 255-260v range? 264 should be the maximum. I realize that theres not a huge margin of error here but these numbers aren't telling me that the thing should just shutdown and not work, even if I could get it to scale back a bit so it slides under the point of needing to shut off. I'm going to have to get back on the phone with sma.

[Markyrocks69]

Ok so I knew this was possible but was hoping it wouldn't come to this point but apparently I can dial back the maximum power output until I can get both inverters to stay on. It's not exactly ideal but I'll be able to keep tweaking it until I find a happy medium. Common sense would say that even if both inverters had to be scaled back to only putting out 5kw maximum 5+5>7.7.... hopefully I wont have to scale back that far. I'm hoping I only have to drop it down to 7kw maybe a hair lower but like I said I can't imagine that its attempting to operate that far out of range. Its pretty crappy the only other thing I might be able to do is get the inverters to sync up so they are both outputting the exact same power so they aren't trying to one up each other.

[Salts]

Switching the inverters around seems like a tremendous amount of work just to for a test. Yes I have checked all the settings to see if they're the same. They look the same to me. With the sma inverters it doesn't allow me to change settings related to the ac voltage parameters ect. I would need to obtain a grid guard code from sma to do that. Setting one inverter a little higher might fix the issue but idk if I'm going to be able to get a grid guard code.

As an update I changed the wiring around a bit to see if it fixes anything. Doesn't seem like it has. It's just weird bc when one inverter is pumping out its maximum the output hovers around 255v. I just checked the voltage in the panel and it says its around 251-253v it kinda steadily fluctuates between the 2 values. So as you can see the voltage drop is relatively small. Now what is stopping the other inverter from operating in the 255-260v range? 264 should be the maximum. I realize that theres not a huge margin of error here but these numbers aren't telling me that the thing should just shutdown and not work, even if I could get it to scale back a bit so it slides under the point of needing to shut off. I'm going to have to get back on the phone with sma.

Well its not like you'd have to change them back unless you discovered the problem. I had to flop out my SMA US6.0 inverter, its just a few wires.. took me an hour to take it off and put a new one on.

An hour of work will tell you if its the wiring or the electronics.

I have a grid guard code, it was a simple process to get it. Needed the code to take my inverter off-grid for AC Coupling to a Sunny Island inverter. That said, I only mess with one setting and followed a specific set of instructions designed for a specific purpose to do it. I wouldn't think of screwing with grid-tie parameters.

By the way, the SMA inverters do not accept 2 gauge wire as far as I know, and if I remember correctly, they specifically say Copper Only. How are you dealing with that? I ran 4ga wire out to my array, but I put in a subpanel breaker box and then wired one of the breakers to the inverter. This allows me to add a 2nd inverter down the road or add a power outlet near the array if I want.

[Salts]

Ok so I knew this was possible but was hoping it wouldn't come to this point but apparently I can dial back the maximum power output until I can get both inverters to stay on. It's not exactly ideal but I'll be able to keep tweaking it until I find a happy medium. Common sense would say that even if both inverters had to be scaled back to only putting out 5kw maximum 5+5>7.7.... hopefully I wont have to scale back that far. I'm hoping I only have to drop it down to 7kw maybe a hair lower but like I said I can't imagine that its attempting to operate that far out of range. Its pretty crappy the only other thing I might be able to do is get the inverters to sync up so they are both outputting the exact same power so they aren't trying to one up each other.

Those two inverters shouldn't even know the other exists. Just my opinion, but I think its that aluminum wire. Every time I have ever had a problem with wiring, it was aluminum wire that was guilty. Who knows, maybe you have a faulty inverter, which is why I say flop them out with each other.. that would tell you for sure.

[foo1bar]

As an update I changed the wiring around a bit to see if it fixes anything. Doesn't seem like it has. It's just weird bc when one inverter is pumping out its maximum the output hovers around 255v. I just checked the voltage in the panel and it says its around 251-253v it kinda steadily fluctuates between the 2 values. So as you can see the voltage drop is relatively small. .

So just in the short wiring from the panel to the inverter you have 4V difference. While not big, I would not discount it.
Presumably you double the current on that, you'll have another 4V on that section.
Then you have the wiring from the panel to the POCO transformer, and how much resistance that has. We don't know how big that is - but it could easily be another 5-10V when you're at full power.

What's the voltage at the panel when you are *NOT* producing anything? If you see a voltage swing from 240V (no production) to 252V (one inverter production) then a good part of your problem is the wiring between your panel and the POCO's transformer.

[Markyrocks69]

They don't know the other exists and that's part of the problem. If one has pumped the voltage up to 255 and the other thinks it needs to go higher to overcome the resistance and so on that seems to be the problem. What would lead you to believe aluminum wire is the problem? I used the anti oxidant and tightened to spec. As far as I can tell the majority of service entrance cable is aluminum, I don't think anyone uses copper for that anymore. Not unless you have a ridiculous long run and various other factors would force that scenario. But I feel like only dropping 2 volts over 180 ft I'd say the aluminum wire is doing a heck of a job.

The inverters have all kinds of watertight conduit running into them so it's not as simple as just disconnecting a few wires.

How am I dealing with the 2 gauge aluminum to the inverters, lol you got me I just shaved the wire to make it smaller to fit....lol no I'm just kidding. I installed a ac safety switch at each inverter that the aluminum connects to one side and on the other side I have 6 gauge copper from the switch into the inverter 🤓

[Markyrocks69]

What's the voltage at the panel when you are *NOT* producing anything? If you see a voltage swing from 240V (no production) to 252V (one inverter production) then a good part of your problem is the wiring between your panel and the POCO's transformer.

The voltage at the panel when nothing is happening is like 252

[foo1bar]

I I attached a pic of how its connected now vs how I'm going to test it.

Looking at your drawing, how is the solar subpanel and the main panel connected?
It looks like the solar subpanel is tap connection of the wires leading to the main panel.
Is that connection a good connection?
What's the voltage in your main panel's busbar vs. the voltage in the solar subpanel when you're producing?

I honestly think the inverters are fighting in the panel bc the breakers are right next to each other and theres no other loads in there. I'm going to split them up hopefully it fixes it. Just kinda annoying.

Really unlikely.
IF the main panel and solar sub panel are tied together with sufficiently low resistance connection you will see no difference between the two things you're planning to do. And I would normally expect a low resistance connection between them - easiest way to check that is just put a voltmeter on the bus bars. - or even from bus bar in one to bus bar in the other while you're producing (should be very close to 0V difference between the ones on the same leg - but there's at least 3 connection points from one panel to the other and usually the connection points are where there can be a problem and a higher resistance.

[foo1bar]

The voltage at the panel when nothing is happening is like 252

So you have no difference in voltage at your breaker panel for solar when switching between producing and not producing? I would expect to see at least a few volts difference.
If it's 252V when not producing, then I think part of your problem is a high-ish POCO voltage. You can ask your POCO what their spec is. If they're out of spec, they'll fix it. If they're in spec for your POCO then you ask SMA to help you change the inverter settings so that it handles the POCO's voltage range

[Markyrocks69]

The subpanel connection is a tap and it's a very good connection. Those taps are top of the line , not some junk. But you're right there is next to no difference, the test basically is a failure lol. And theres next to no difference between the 2 panels as far as voltage. The only connections between the 2 panels are the nuetral and ground. That all seems legit. The difference I was hoping for was the house loads being in between one solar breaker and the other hopefully dropping voltage just a bit to possibly make the difference but theres obviously such small resistance there that it's not making a bit of difference

[Markyrocks69]

So you have no difference in voltage at your breaker panel for solar when switching between producing and not producing? I would expect to see at least a few volts difference.
If it's 252V when not producing, then I think part of your problem is a high-ish POCO voltage. You can ask your POCO what their spec is. If they're out of spec, they'll fix it. If they're in spec for your POCO then you ask SMA to help you change the inverter settings so that it handles the POCO's voltage range

The main panel sits around 252 when nothing is happening, when its producing it seems to fluctuate between 251 -253 pulses. I don't think it needs to ramp up much higher than the idle system voltage it just needs to be higher so it can overcome the resistance. More power doesn't necessarily automatically mean the inverter needs to keep pushing volts up, more power equals more resistance and the resistance is why it goes up. If the voltage after the transformer is 252.8v the voltage from the inverter only needs to be 252.9v bythe time it hits that point for the electricity to flow up stream.

I agree that I have a couple options, I'm assuming that the voltage is high in this area bc is rural and many people's houses are far back from the road. The ordinance is you cant build within 50ft of the road anyways. My house is roughly 150ft from the road my one neighbor across the street house is like 500 feet away from the road. The point of this was to hopefully find an immediate fix. Going through sma and the poco is kinda a long path to travel. I will probably explore all options to get the most out of the system. The way this system is designed though is to get the most out of bad conditions. In western pa the weather and conditions aren't exactly ideal for solar so I honestly expect the system to operate more in cloudy, rainy, snowy conditions than at its peak. Like the past few days have been ideal but that's a rarity. Today is partly clowdy. Were moving into October and usually October weather starts a serious nose dive and stays crappy until like may lol. I think the average peak solar irradiation here during the winter is less than 2 hrs lol. So again fringes.

[Salts]

Marky,
I'm confused. You said each inverter is on its own set of aluminum 2ga wires. I understand you have somewhere around 180 feet to the furthest inverter and 150 feet to the closest inverter.

Are you saying that each inverter has its own set of 2ga wires going all the way back to the breaker box in your home?

[Salts]

The voltage at the panel when nothing is happening is like 252

That's high.. way high. I've never seen more than 246 volts from a POCO anywhere.

So with the inverters off, your POCO is giving you 252 volts? Seems like a nice way to limit solar production.

[Markyrocks69]

Marky,
I'm confused. You said each inverter is on its own set of aluminum 2ga wires. I understand you have somewhere around 180 feet to the furthest inverter and 150 feet to the closest inverter.

Are you saying that each inverter has its own set of 2ga wires going all the way back to the breaker box in your home?

Yes. They are 2 separate circuits. Each with its own wires, there are no combiners ect. Theres 2 safety shutoff switches in there so it's not directly from inverter to panel.

Yes roughly 252v at idle. I highly doubt it has anything to do with solar, solar is not very popular around here. Honestly in this area solar isn't financially feasible unless you DIY. So the only people who have it are either rich and don't care, elderly people who are just getting swindled or someone like me that paid cash for my system and installed it myself. So like I said few and far in between, I only know of one other pv system within like a 5 mile radius from my house. As I said b4 my money is on the fact that it's a rural area and the houses are generally far away from the transformer.