High Voltage over L1-L2

[sdscuba]

All the way to the transformer? Or just to the service? I thought you said above the service was #6?

It was thought that it was #6, but in fact #8 from the street to the service panel.... ~ 15' length. From the transformer to the street hookup, I believe is #0 just based on the size.... as there are no outer markings.

So...
#0 Transformer to Street hookup ~100'
#8 Street hook up to Service Panel (with 2 - 40amp breakers!) ~ 15'
#8 Service Panel to Breaker Panel ~50'
#8 Breaker Panel to Inverter ~50'

I calculate that your voltage drop along the inverter output will be a volt or two higher with #8 than with, say, #4. If this were the US and it was a 100A service with a #2 feeder to the sub then you'd probably have a couple extra volts of cushion. Still, it doesn't change the nature of the problem. It's about 1% Vdrop. I'm sure I've ever seen an nominal 240V supply read higher than about 255V in my work. (Which has been all in fairly urban areas in the states, to be sure.)

Will look into pulling #4 from street hookup to breaker to inverter with the hopes of at least getting in down a few volts as this might be enough to stop the inverter from tripping.

Still working on getting electric company to agree a problem exists.

Thanks for all the input!

 

[69gp]

I've searched the forum to find similar issues with what I am trying to resolve, but didn't see an exact answer or resolution. Here's the problem I'm trying to resolve.

I have 22 - 250w solar panels with a Sunny Boy 5000 inverter.
The system has been flawless over the past 2 years.

Voltage at the service panel, that I have measured, ranges from 255v to 265v. :blink:
This is not a US installation..... install is in Mexico.

Recently, about 10 times over the past 2 months, the inverter will report grid fault errors when the voltage over L1-L2 exceeds 264v.

I've had the PoCo here several times to troubleshoot this. Each time they come out, they report no problems.
L1 and L2 would read between 128-132v. This they say is within their acceptable range.

Will a buck transformer do the trick, if installed at the service panel, to maintain 240v over L1-L2?
And will a transformer work with a PV system installed?

Any feedback will be greatly appreciated.

Greg.

.

 

[sdscuba]

I would check with Sunny Boy of what the alarm triggers are set for. If the inverter is setup for 240 volts then I am sure the alarm would be legit. They may be able to give you some direction if this is going to hurt the inverter. They may have an accessory kit to run at a higher voltage along with being able to make adjustments with the alarm settings.

I would start there before going to buck boost transformers.

I'm awaiting for a reply from SMA as to if changes can be made to raise the tolerance. I doubt any harm will be done to the inverter as this is why they auto disconnect it from the grid when a disturbance or grid fault is triggered.

My thoughts on a buck transformer was to protect assets inside the house as well. Worried that the life expectancies for items such as refrigerator, washer/dryer and tv's will be diminished or even burn out!

 

[gadfly56]

Thanks for the feedback!

Inverter is approximately 30' from the service panel.

They have seen voltage in and around 133v per leg. This they say is within tolerance. They say power here in Mexico is not 120v but rather 127v.

They are routinely hitting 260v-264v.

For what it's worth, Wikipedia backs them up. With a 5% allowable swing on service side voltage, up to 267 volts could be considered "normal".