I did not consider that the buzzing is not sounds, instead it is electrical interference picked up by an unshielded microphone.

Sorry, I must be confused. Where is everyone getting the idea that the sound(s) are coming from an unshielded microphone? Have I missed something?

 

I had assumed that "the buzz" was acoustic, being produced by every item connected to the solar panel tied mains. I did suggest a directional microphone for locating the source.

 

Sorry, I must be confused. Where is everyone getting the idea that the sound(s) are coming from an unshielded microphone? Have I missed something?

This is a thing that happens around here if you don't stay on top of things and keep discussion steered in the right direction. We (not everyone, but as a whole) sometimes get distracted by squirrels or whatever and stampede off in unforeseen directions. Totally normal.

So, it is not EMI on an unshielded microphone. It is acoustic noise faithfully recorded by an unmolested microphone. So we can stop discussing the microphone.

 

This is a thing that happens around here if you don't stay on top of things and keep discussion steered in the right direction. We (not everyone, but as a whole) sometimes get distracted by squirrels or whatever and stampede off in unforeseen directions. Totally normal.

So, it is not EMI on an unshielded microphone. It is acoustic noise faithfully recorded by an unmolested microphone. So we can stop discussing the microphone.

Understood, appreciate that clarification.

I made a discovery today, much to my dismay. Well after dark (about 2 hours), the neighbor's solar array was still making that lovely sound and all my lights were still flickering. As far as I can tell, they do not have a battery assembly on their solar. Most home owners do not, in the state I live in.

I decided to walk down the neighborhood to see if other substations in my area were making that lovely buzzing sound. As far as I can tell, it's just the service substation for my house and my neighbor's. I do not believe that anyone else is tied to it. 4 doors down from me is a second substation that had none of the related noise. It sounded like a standard transformer.

TL;DR, my neighbor and I are on the same transformer and it has that horrid sound and flickering lights in my house. The transformer 4 doors down does NOT and sounds like a normal transformer. I am going to try calling my power supply company again and get them to come check the transformer itself, whereas last time they only checked my tie-off.

 

And how did the power company respond when you brought this to their attention?

 

What part of the world is the TS located in? There are areas where flickering power is common.

 

So much for the solar inverter theory. TS assured us before that before that the buzzing happened only during the day. Now it occurs after dark as well.

On a more optimistic note, I asked in post #3 whether neighbors on the same transformer and neighbors on different transformers experienced the buzzing, and 81 posts later I finally get the answer.

 

So much for the solar inverter theory. TS assured us before that before that the buzzing happened only during the day. Now it occurs after dark as well.

I agree this is A nail in the coffin of the inverter theory but by no means the final nail, and I see no reason to wipe it completely off the table.

As far as I can tell, they do not have a battery assembly on their solar.

No offense to @geong1 but I do not think he is really qualified to make this speculation. I'm not either, so don't take it personally.

If the inverter is suspect already, should it be any surprise that it acts unpredictably (not running, running erratically, running after dark, etc.)? I don't know the specifics of battery-backup solar systems but I googled a bit and saw terms like "night mode." But how do inverters know when it's "night?" Based on a timer or on voltage? Some sources indicated an inverter might enter "night mode" on a cloudy day, so I assume it's based on voltage. If demand in the home was low or nil during the day and the (hypothetical, maybe nonexistent) battery bank were still charged to daytime levels after dark, would the inverter remain on after dark? What if the installer did not set up the inverter correctly for the battery bank voltage, and so the inverter thinks the bank is overcharged? Are there any other settings in an inverter (with or without battery backup) which, if set incorrectly, could manifest in a way that explains both making this buzzing sound and running after dark?

 

running after dark, etc.)? I

That’s a good trick. Can you tell me how to make mine run after dark?

Of course, it is possible that he actually does have batteries, which is further evidence that the statements of the TS are all suspect.

 

That’s a good trick. Can you tell me how to make mine run after dark?

Overcharge the batteries maybe? IDK. Seems plausible to me, but maybe only because I'm ignorant.

I'm actually curious, and if I had a solar inverter I would test it by putting a battery charger on the bank after dark and pumping the DC voltage level up to daytime levels and see if it comes on. If it does, then it should be equally plausible that an inverter setting is at fault. If your bank is 48V but the inverter is configured for say a 40V bank then the inverter will always think the bank is overcharged and (in my theory) continue running until the bank is discharged to 40V.

 

Of course it would come on after dark it has batteries. What did you think the batteries were for if not to produce power when there is no sunlight?

Most homes solar installations, mine included, do not have batteries.

 

Of course it would come on after dark it has batteries. What did you think the batteries were for if not to produce power when there is no sunlight?

I think you and I do not communicate on the same frequency.

Most homes solar installations, mine included, do not have batteries.

Noted. Thanks.

 

I think you and I do not communicate on the same frequency.

Apparently. This statement implies to me that you think it would be wrong for the inverter to run at night in a battery backed solar installation, or that that inverter can run with no power input if not battery backed.

If the inverter is suspect already, should it be any surprise that it acts unpredictably (not running, running erratically, running after dark, etc.)?

 

Those folks who live off grid will certainly have batteries for their systems. And I would assume that the main purpose of having a solar power array would be to avoid dependence on the grid, and that will certainly require batteries charged during sunlight and providing power during darkness. Even more interesting is that the mode of operation may change a bit from charging batteries during daylight to discharging them during darkness. So whatever noise is generated in one mode may not be generated in a different mode.. The fact is that a typical solar power system is a bit complex, and some portions may generate electrical noise.

 

Apparently. This statement implies to me that you think it would be wrong for the inverter to run at night in a battery backed solar installation, or that that inverter can run with no power input if not battery backed.

If the inverter is suspect already, should it be any surprise that it acts unpredictably (not running, running erratically, running after dark, etc.)?

Ok I understand you now, and after re-reading my posts I can understand how you reached that conclusion.
I did not mean to imply that; I meant the opposite actually.
I meant that if the neighbor's system did have battery backup then it could conceivably still be polluting that small corner of the electrical grid after dark, but that if it is doing this it might reflect poorly chosen parameters in the inverter (battery bank nominal voltage not set properly I would suspect). My underlying assumptions behind this are:

• During the day the system should be trying to power the home from solar as much as possible, and if there is surplus, send it into the grid.
• During the night the system should be dormant, home powered from the grid.
• The battery is primarly for backup purposes.
• Although it is possible, it is not ideal for the inverter to be discharging the battery at night and sending its stored energy out into the grid.
  (because then it is not available in case of utility outage, its primary purpose)
• The system probably detects "day" and "night" based on voltage. That makes more sense to me than based on a timer. Especially if the unit is capable of having other sources like wind turbine involved, in which case it would make total sense to be powering the grid during the night.

Maybe my assumptions are bad, let me know.

If my assumptions are correct and if the system detects higher than nominal battery voltage then it should indicate that the sun is out, PV array is generating more power than the house is consuming, and it should be sending as much excess power as it can, to the grid. But what it might mean is that the the nominal voltage setpoint in the inverter is too low, so it's trying to power the grid off battery power during the night.

My probably-haribrained ideas here are pretty far off on a speculative tangent and not contributing much to the thread so I don't want to continue this. Feel free to correct me if I'm wrong about any of this but don't feel dissed if I don't reply to it.

 

I certainly am no expert on solar power, but my understanding is that systems are either grid tie or not, and grid tie systems cannot work from a battery, and cannot supply power to the house if the grid is down. They need the grid to be active in order to run at all. A different kind of inverter is needed for off grid operation.

 

I certainly am no expert on solar power, but my understanding is that systems are either grid tie or not, and grid tie systems cannot work from a battery, and cannot supply power to the house if the grid is down. They need the grid to be active in order to run at all. A different kind of inverter is needed for off grid operation.

I'm also not an expert, far from it. But the system i described exists, even if it doesn't work totally like I think it does.

https://realgoods.com/grid-tie-solar-battery-backup

 

What is described there sounds like two different inverters bolted together. Certainly possible, but not commonly done I expect.

 

First,"Grid Tied" is the only scheme in which the system can sell power back to the utility. and second, why spend anything for a solar power system that is not able to deliver power when the grid fails????? THAT ALONE is the primary reason to invest in a solar power system. Certainly the payback in power cost is not that much, given the price of most solar power systems. At least in most areas that I am familiar with. There may be exceptions where power from the utilities is terribly expensive, of course.

 

why spend anything for a solar power system that is not able to deliver power when the grid fails?????

Because it is cheaper and avoids burning fossil fuels maybe? My system will pay for itself in about 8 years. It also adds nearly the full price I paid to the value of my house. And the economics only keeps getting better as utility rates go up year after year.

Nearly all residential systems are grid tied without batteries. For grid outages, a generator is far cheaper than a solar / battery system.