Solar Edge major unresolved problem

[Treepmeyer]

I'm making a little headway, at least in my understanding. Solar Edge says that they expect a 3% voltage increase with power generation with a 200ft. run, such as I have. With grid voltage set at 250v, I should expect to see 257.5v. However, I routinely see 260v which is the inverter shutdown threshold. They also say that excessive voltage increases are due to wire size being too small. However, they confirm that the existing #6 wire is per spec and should be fine.

The power company volunteered to dial down the local regulator to 248v and Solar Edge said that they can bump the shutdown threshold up a couple of volts. The combination may preclude the majority of shutdowns. I will also have an electrician the PV array connections and apply the conductive grease, as recommended here. We'll see. Thanks for all the comments and advice. I will let you know what happens. It only took a full year to get to this point!

[oregon_phil]

There is something else you can do....it will take some time and effort on your part. It appears that the voltage rise (drop in electricians terms) is increasing over time. This leads me to believe that you have high resistant connections in your system. And those connections are getting worse over time.

My suggestion is to inspect EVERY connection in the system, clean and apply silver conductive grease on every connection. Do not confuse this with dielectric grease which will have the opposite effect. You are only out your time and about $50 worth of silver grease.

Good luck.

I believe all connections should be properly torqued to manufacturers specification too. Solar connections go through more thermal extremes than normal electrical connections as pclausen thermal images showed us.

[DanS26]

Something that has not been mentioned is that are their any new solar producers that have come on line in your neighborhood? Surely your POCO should have forewarned you of those additional systems if any.

[DanS26]

Use this......

https://www.amazon.com/Silver-Conductive-Grease-Temp-70/dp/B0047D3QLG/ref=sr_1_1?keywords=silver+conductive+grease&qid=1664934299&qu=eyJxc2MiOiIzLjcyIiwicXNhIjoiMi43NCIsInFzcCI6IjIuMDcifQ%3D%3D&sr=8-1&ufe=app_do%3Aamzn1.fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840

But use it sparingly on the connections, if it oozes it can create short circuit.

[Treepmeyer]

I will ask Solar Edge support tomorrow about the effects of wire distance and guage. I will also clean all the contacts. Would Deoxit work? I use that on all my stereo contacts.

By the way, where do I find the margaritas?

[DanS26]

There is something else you can do....it will take some time and effort on your part. It appears that the voltage rise (drop in electricians terms) is increasing over time. This leads me to believe that you have high resistant connections in your system. And those connections are getting worse over time.

My suggestion is to inspect EVERY connection in the system, clean and apply silver conductive grease on every connection. Do not confuse this with dielectric grease which will have the opposite effect. You are only out your time and about $50 worth of silver grease.

Good luck.

[Mike 134]

Before throwing $4100 at the issue, I'd first ask Solar edge if the distance and wire gauge would have an effect. Remember we're offering advice from the "internet cafe" and they have a margarita special tonight.

[Treepmeyer]

I have a quote from my current installer to replace the #6 line with a #4 line for $4100. That was what the service electrician recommended initially. Then the installer's master electrician stepped in arguing that the #6 wire was OK and the problem was likely the power company's ground/neutral connection. He was trying to save me some money. But then the tier 3 Solar Edge service people agreed that the #6 line was OK, so I discounted the line guage as the problem. Sounds like everyone here agrees that I need to go ahead with the #4 line replacement.

[oregon_phil]

Good point about tighter specs. For my SMA 7.7-40 grid parameters, there is a set of parameters to follow when the inverter is up and running and another set of voltage parameters to follow after a fault occurs. Lower reconnection limit= 106VAC, Upper reconnection limit = 127 VAC (obviously one leg). I couldn't find anything in SE documentation that details these exact parameters however.

I think my SMA inverter would act just like the OP's inverter in his situation due to the voltage reconnection limits.

[peakbagger]

FWIW I have three arrays that feed into a subpanel and then the subpanel is tied to my main panel via a wire run that goes out to a utility disconnect switch, a production meter and then on to the panel. When I first installed it I reused some existing wires that were borderline for the new application and I was having occasional issues with inverters staying synched to the grid. It wasnt all the time but on occasion it took awhile. I ran the numbers on sizing and replaced the wires with a larger gauge and the problem went away.

Usually inverters are set up with tighter than standard voltage range, there is usually an option through the installer of the manufacturer to bump up that range if things are acting weird. I have a friend that had bad power from the utility and that tided hm over until the utility hooked up a power quality analyzer and found out problems with their grid. This seems to happen far more in the country than in the city.

[Mike 134]

Solar Edge, the original installer, and the current installer's master electrician are all wrong? Depends on the allowed voltage drop. Did anyone tell solar edge the wire size and distances?

Let's assume that the wire is undersized, what would the effect be? Would it heat up, with increased resistance? Would that result in a voltage increase? And would that be proportional to the amperage produced by the array? I'm trying to understand how the symptoms we observe can be explained.

Your #6 will have a voltage drop of 3.1% or almost 8 volts. Perfectly acceptable in the real world. NEC code "recommends" no more than 3% you're a tick over.

Your questions should be asked to the solar edge tech support how a 200' run with 3% voltage drop will impact their inverter.

[SunEagle]

Solar Edge, the original installer, and the current installer's master electrician are all wrong?

Let's assume that the wire is undersized, what would the effect be? Would it heat up, with increased resistance? Would that result in a voltage increase? And would that be proportional to the amperage produced by the array? I'm trying to understand how the symptoms we observe can be explained.

They may have errored on the lower cost side. While a #6 should be able to carry 40amps my fear is that you may exceed the 2% voltage drop allowed by the NEC. That could also cause issues on the input side of the panel which could lead to over heating.

And yes a voltage drop calculation is based on the amount of amps the distance and the resistance of the wire. If it was for a DC voltage calculation it would need to include both the + and - distance runs. Which is probably close to 400 feet.

Since it is an AC voltage run you still might be a little shy of the voltage drop allowed

[Treepmeyer]

Solar Edge, the original installer, and the current installer's master electrician are all wrong?

Let's assume that the wire is undersized, what would the effect be? Would it heat up, with increased resistance? Would that result in a voltage increase? And would that be proportional to the amperage produced by the array? I'm trying to understand how the symptoms we observe can be explained.

[SunEagle]

It is #6 which both Solar Edge and the installer's electrician said is appropriate.

That #6 wire will not carry 40amps or work to stay below 2% voltage drop over 200ft. I think the installer's electrician is wrong.

[Treepmeyer]

It is #6 which both Solar Edge and the installer's electrician said is appropriate.