My panels buzz when I touch the frames?!

[Handmade Matt]

I have 380watts of PV at around 80volts.
It's on a ground mounted wooden frame that I have made.
When I touch the aluminium frames there is a buzzing noise.
Everything's working well.
Is this OK? Do I need to earth the panels to a grounding rod maybe? Pros and cons of doing that?
Thanks.

[Sunking]

Is the wind blowing when you do this? Grounding will do nothing.

[Handmade Matt]

Is the wind blowing when you do this? Grounding will do nothing.

Wind?! How do you mean? I don't think the wind has anything to do with it.
When I touch the frame it buzzes, that's all.

Grounding will do nothing.

So no need for that then.

[inetdog]

Wind?! How do you mean? I don't think the wind has anything to do with it.
When I touch the frame it buzzes, that's all.


So no need for that then.

Is the buzz a constant 60 Hz or 120 Hz audio frequency? If so be very cautious.

The first thing I would do is measure the voltage from the panel frames to a good ground reference.
Then I would (carefully) check to see whether the buzz comes when you touch the frames with an insulated object (rubber gloved hand, dry stick, etc.) or only when you touch them with your bare skin. If the latter, be very very careful since there is probably a dangerous AC voltage/current combination present on the frames. Get help from a qualified electrician before proceeding!

The voltage measurement may be high (even close to 120 volts AC if the panel frames are not grounded at all) but if the current is limited to under a milliamp it may not be a great hazard. But regardless of whether or not one side of the Panel output DC is grounded, the panel frames MUST be grounded effectively for safety.

[billvon]

I have 380watts of PV at around 80volts.
It's on a ground mounted wooden frame that I have made.
When I touch the aluminium frames there is a buzzing noise.

Is this a grid tied or off-grid system? Are there utility transmission lines nearby? I'd suspect a grounding problem if it's a 60Hz buzz. As another poster mentioned, measure AC voltage from frame to ground. It should not be more than a few volts. Also measure current from frame to ground. It should be tiny (milliamps.)

Do I need to earth the panels to a grounding rod maybe? Pros and cons of doing that?
Thanks.

You ALWAYS need to earth the panels to ground. Failure to do that can result in a risk of fire or (in higher voltage systems) risk of electrocution in the case of a conductor to frame fault.

[Handmade Matt]

I've solved it. It was silly... So here it is:

I had an audio hiss/ buzz some time ago on my hifi, so I bought a mains filter. I wired that in and it needed earth which I earthed to the earth ring of our workshop (on grid.) So the AC is feedback from the grid earth ring. Silly and dangerous. As soon as I removed this my hifi hiss comes back but the solar panels aren't "live" anymore. I'm going to go and buy and earth spike tomorrow and use that instead for my filter.

You ALWAYS need to earth the panels to ground. Failure to do that can result in a risk of fire or (in higher voltage systems) risk of electrocution in the case of a conductor to frame fault.

I run at around 80volts. Is this considered high voltage?
SunKing say earthing does nothing, you say I should earth the panels... Anyone else care to comment? I'm confused about that one!?

[Sunking]

So no need for that then.

No Matt that is not what I mean. I am not even going to go into what you need to do. It takes more than just a rod stuck into the ground. That would do nothing to protect you other than give lightning a path to earth, or operate a utility transformer fuse if the 13.2 KV lines fell on the panels which there are none to fall.

What might be happening is you have some wiring crossed and feeding AC back to the panels on the DC line. Disconnect the panels and see if they still buzz.

[billvon]

I had an audio hiss/ buzz some time ago on my hifi, so I bought a mains filter. I wired that in and it needed earth which I earthed to the earth ring of our workshop (on grid.) So the AC is feedback from the grid earth ring. Silly and dangerous. As soon as I removed this my hifi hiss comes back but the solar panels aren't "live" anymore. I'm going to go and buy and earth spike tomorrow and use that instead for my filter.

Ah, the noise was coming out of your _radio_? That explains a lot right there. Yes, that points to an entirely different set of potential problems.

I run at around 80volts. Is this considered high voltage?

Fairly high for DC. If you're working on them and you're wet, you could get a surprise.

[Handmade Matt]

Ah, the noise was coming out of your _radio_? That explains a lot right there. Yes, that points to an entirely different set of potential problems.

I don't think the noise was coming from my hifi. It was coming from the grid earth ring. I was earthing my mains filter to the earth ring of my workshop which is on grid. There must be some appliance leaking in my area putting some power through the earth... This was somehow coming back through my system and making the panel frames "live" with 1.5volts AC.

No Matt that is not what I mean. I am not even going to go into what you need to do. It takes more than just a rod stuck into the ground. That would do nothing to protect you other than give lightning a path to earth, or operate a utility transformer fuse if the 13.2 KV lines fell on the panels which there are none to fall.

Can anyone point me to some further reading about earthing then? I have searched around and read a bit here and there but I am unsure and am keen to learn, I don't expect other people to do all the work for me, I'm sorry if it comes across like that.

What might be happening is you have some wiring crossed and feeding AC back to the panels on the DC line. Disconnect the panels and see if they still buzz.

I believe it was AC coming from this grid earth that I was using to earth my mains filter. Now that I have removed this my Hifi buzzes again but the panels are no longer "live" with 1.5volts of AC.

[Sunking]

I assume you are using a digital meter right? That 1.5 volts is most likely a ghost or phantom voltage due to the high input impedance of your meter. Try this: set your meter up to read AC volts. Take one probe and hold it between your two fingers on your left hand, repeat with the other probe in your right hand. Now read the voltage.

The other thing is what you are describing is step potential voltage difference. It is caused by utilities using the earth as a return conductor in a multi-grounded neutral system. There is virtually nothing you can do about it and not really something to worry about unless you are a farmer with dairy cattle or live stock not drinking from a tank or giving milk.

Your hiFi is buzzing because you are either using two different ground points, or missing a ground. All equipment grounds need to come from a common point in a star fashion and no daisy chaining.

[Handmade Matt]

I have stopped using the grid earth in the workshop now, I bought a 4foot earth rod and have driven it into the soil under my cabin. It's damp clay so it should make a really good earth. I've connected the mains filter to this now and am back with the same problem. There is AC power in my panel frames. I can feel the electricity in my finger and now measure 5volts AC with my meter.

The only earth in my whole system is this earthing rod, the only connection to it is this mains filter that I bought on eBay to get rid of the HiFi buzz.
NOTHING else is earthed at them moment.

I assume you are using a digital meter right? That 1.5 volts is most likely a ghost or phantom voltage due to the high input impedance of your meter. Try this: set your meter up to read AC volts. Take one probe and hold it between your two fingers on your left hand, repeat with the other probe in your right hand. Now read the voltage.

Yes, it's a digital meter. I get no reading between my hands and am not getting 5volts AC between the panels and the wet clay underfoot.

Your hiFi is buzzing because you are either using two different ground points, or missing a ground. All equipment grounds need to come from a common point in a star fashion and no daisy chaining.

The HiFi is connected directly to the inverter output using a 6meter extension cable and a couple of four way extenders to power a laptop, the HiFi, and a monitor. The extension is on the AC side. The inverter is powered directly from the battery bank with short heavy duty cables. None of it is "grounded" to "mother earth" apart from this mains filter that reduces the audio buzz in the HiFi but makes my panel frames live.

Something's not right?!
Thanks so much for all your input everyone.

[wotechsolar]

you are so clever, use the wooden supoort, which can reduce your whole cost. great.

[billvon]

The HiFi is connected directly to the inverter output using a 6meter extension cable and a couple of four way extenders to power a laptop, the HiFi, and a monitor. The extension is on the AC side. The inverter is powered directly from the battery bank with short heavy duty cables. None of it is "grounded" to "mother earth" apart from this mains filter that reduces the audio buzz in the HiFi but makes my panel frames live.

Then my guess as to what is happening:

Your filter contains a lot of capacitors and inductors that couple between hot, neutral and ground. They are sized so that they present a high impedance at 60hz (i.e. do not "steal" any power away at low frequencies) but present a low impedance to higher frequencies (i.e. they short the noise to ground.) If your inverter is noisy, then the energy in the high frequency noise is being shunted from hot (and potentially neutral) to ground.

On a normal system this doesn't do anything since the system neutral is grounded near the service entrance. However since you have no other grounds, there is no return path for the current your filter introduces to the ground - so the entire system "bounces" up and down as current is shunted through those capacitors.

Low frequencies couple only poorly to things like panel frames, but higher frequencies couple a lot better. Thus I'd bet that you are seeing some high frequency common mode noise on your entire system, and that includes the frames of your panels (due to the capacitive coupling to the rest of the system.)

[Handmade Matt]

...Thus I'd bet that you are seeing some high frequency common mode noise on your entire system, and that includes the frames of your panels (due to the capacitive coupling to the rest of the system.)

Thanks. So is it OK? Everything works fine. Is it dangerous or am I causing any damage to any components? Is there a solution? (Essentially, solving my audio buzz in the HiFi and eliminating the filter would solve all of this.)

I feel like I (we) are getting somewhere with this, it's like being a detective! Thanks everyone!

[Sunking]

Matt I have tried to help you with all your questions up to this point. So I am going to give you the best answer and advice on this subject and I mean No Offense but you are in way over your head. You really need to hire an electrician with experience to help you out on this one who is familiar with your local codes and solar battery systems.

I can tell you right now adding a rod at the panels will do you absolutely no good and just cause you even bigger problems. It is not the rod itself but the 15 other things that have to be done like dig a trench and all the other things you do not know about or even know what questions to ask.

So take it from a PRO, hire a PRO to take care of this correctly. Otherwise you could burn your home down or get yourself electrocuted. This will be my last reply to this thread.

What I see as problem is you are in the UK, and said your HiFi is plugged directly into the inverter. This tells me a few things. 1. your inverter is likely 240 VAC being a Euro unit. 2. If you inverter has receptacles built into it that it is a mobile unit made for Rv's Boats, and Autos and not meant to be used in premise wiring systems or has any means to properly earth the system. It is not made to be earthed or as us Yanks would say a Grounded System.

Good Luck and be safe.

SK