SHOCKED! by my solar panel!!!

[Murby]

I'm installing a 7.5KW ground mount solar system. My wife and I were wrapping the individual solar panels in an old blanket because we had to slide them up the array into position and didn't want to scratch the pre-installed panels we were sliding them across. I had to climb a ladder on the back side and pull them up with a rope into position.

Anyhow, before putting the panels up, we'd put a blanket down on a large pallet, lay the panel on the blanket and wrap it up.. then pick up the entire thing and set it on the array on top of the lowest panel.. I'd then climb the ladder on the back side and hoist it up. My system is using 28 Solar World panels (SW270) and when we were installing the last row, we got shocked by the power the panel was generating!

The panel was still on the pallet..(not even touching the array) The original wire tabs still installed with the orange tape securing them to the back of the panel, MC4 connectors intact.. nothing was wet.. and we had done this same procedure 24 times previous without incident.

When we went to pick the panel up, both of us felt a tingling sensation in our hands.. Being familiar with what 36 and 48 volts DC feels like, I knew exactly where that voltage was coming from..

I can not figure out how this could be possible. Upon testing the panel with a meter, I'm getting about 36 volts and 8 amps (varies with tilt to sun).. I also checked the voltage from the positive to frame and negative to frame and not seeing anything...

Any ideas?

[sensij]

I can not figure out how this could be possible. Upon testing the panel with a meter, I'm getting about 36 volts and 8 amps (varies with tilt to sun).. I also checked the voltage from the positive to frame and negative to frame and not seeing anything...

Any ideas?

Did you try to measure the resistance between each lead and the frame? I'd do it at night.

[max2k]

I'm installing a 7.5KW ground mount solar system. My wife and I were wrapping the individual solar panels in an old blanket because we had to slide them up the array into position and didn't want to scratch the pre-installed panels we were sliding them across. I had to climb a ladder on the back side and pull them up with a rope into position.

Anyhow, before putting the panels up, we'd put a blanket down on a large pallet, lay the panel on the blanket and wrap it up.. then pick up the entire thing and set it on the array on top of the lowest panel.. I'd then climb the ladder on the back side and hoist it up. My system is using 28 Solar World panels (SW270) and when we were installing the last row, we got shocked by the power the panel was generating!

The panel was still on the pallet..(not even touching the array) The original wire tabs still installed with the orange tape securing them to the back of the panel, MC4 connectors intact.. nothing was wet.. and we had done this same procedure 24 times previous without incident.

When we went to pick the panel up, both of us felt a tingling sensation in our hands.. Being familiar with what 36 and 48 volts DC feels like, I knew exactly where that voltage was coming from..

I can not figure out how this could be possible. Upon testing the panel with a meter, I'm getting about 36 volts and 8 amps (varies with tilt to sun).. I also checked the voltage from the positive to frame and negative to frame and not seeing anything...

Any ideas?

may be just static from all the sliding?

[max2k]

Did you try to measure the resistance between each lead and the frame? I'd do it at night.

you can try measuring voltage during day between frame and each lead- should be 0V.

[Mike90250]

A tingle or buzz feeling is AC, either leakage from a ungrounded device (not likely) or some induced voltage from power lines. I used to get that from my car parked in the street, but only when touching the chrome gutters above the door frame and standing on the lawn, Any overhead Ac powerlines nearby ?

If it was DC, there would be a notice in the newspaper.

[sensij]

If it was DC, there would be a notice in the newspaper.

Just one panel is less than 40 V, not going to do much against the resistance of the body, hand to hand under the conditions described.

There is also the small detail that the frame is anodized, and probably not conductive unless scratched. Probing it for voltage or resistance won't give accurate results if the lead is only touched to the surface without getting through that oxide layer, and it makes it harder to guess what the OP (or his wife) was holding.

[Murby]

may be just static from all the sliding?

This wasn't a single zap type of shock.. it was a continuous tingling as we were holding the panel wrapped in the blanket and didn't cease until we put the panel down. We both felt the same sensation.

[Murby]

A tingle or buzz feeling is AC, either leakage from a ungrounded device (not likely) or some induced voltage from power lines. I used to get that from my car parked in the street, but only when touching the chrome gutters above the door frame and standing on the lawn, Any overhead Ac powerlines nearby ?

If it was DC, there would be a notice in the newspaper.

I have extensive experience with both 36 volt and 48 volt forklifts and can say with a high level of certainty, this was around 36 volts dc.. Between 30 and 60 volts DC, I have so much electrical experience that my fingers are almost like multimeters.. This wasn't a static shock "zap" and it wasn't AC because there was nothing to conduct AC..

[Sunking]

In order to be shocked or electrocuted, there must be a complete circuit. In a human body there must be a point for current to Enter, and another point for current to Exit.

In an AC system that is pretty easy to do because we reference our AC systems to dirt. All you need to do is have your feet below your knees standing on something, then touch an energized circuit and you now because part of the circuit with current entering your hand, flowing down to exit through your feet. Or one hand against say an equipment frame like a breaker box, and the other hand on a live circuit.

Not sure what happened or how it could have happened. Because the only way a panel; can shock you is if you place yourself between both polarities. Now with most panels, the Frames are not Bonded to either circuit polarity and that would most certainly would be required to electrocute you and only half the requirements. OK having said that there are a very very unwise panel manufacturers that Bond the positive circuit polarity to the Solar Panel. To receive a shock all that is required is for you to touch the panel frame and the Negative Circuit conductor.

So to the OP here is the answer you are looking for. You either bought a Solar Panel using Bonded Frames like Sun Power (I think is one), or you have a faulted panel shorting a circuit conductor to one of the panels polarity.

Here is an Oxymoron for you. In the electrical world, most of it anyway. If a circuit conductor comes in contact with equipment framing, chassis, raceway ect, is called a Fault, operates breakers, and sets off alarms and whistles to alert you of danger. Sun Power calls it normal when they bond Positive to the Frame.

[Sunking]

Did you try to measure the resistance between each lead and the frame? I'd do it at night.

Take it you have never done this. No need to do it at night, and in fact if you did would not work great if at all. Waste of time and so DIY

Besides you would not measure resistance silly, at least not initially if even at all. Who taught you that? A Pro would measure for DC Voltage and test between the Frame and each circuit conductor polarity for voltage. If you see a Voltage on one conductor and not the other, guess what that means?

It means the Polarity with ZERO VOLTS is faulted or bonded to the frame, and you know have a Hot Conductor with voltage on it. Then if you want you can confirm by measuring resistance on the conductor with ZERO VOLTS to the Frame. An Apprentice would not waste his time doing any DC Resistance. Instead he would have used his time boxing the panel back up and getting a replacement.

[sensij]

Sun Power calls it normal when they bond Positive to the Frame.

Sunpower never internally bonded positive to frame. On panels made 10 years ago or so, they recommended that the DC+ be grounded for better performance ( instead of grounding DC-, as was conventional at that time), but that requirement was eventually designed out.

[sensij]

It means the Polarity with ZERO VOLTS is faulted or bonded to the frame, and you know have a Hot Conductor with voltage on it. Then if you want you can confirm by measuring resistance on the conductor with ZERO VOLTS to the Frame.

So you are saying that after measuring voltage ( which the OP said he did in the first post), you would measure resistance to confirm ( which is what I posted). Glad we agree.

[Sunking]

So you are saying that after measuring voltage ( which the OP said he did in the first post), you would measure resistance to confirm

Not me, I would box it up. I already know it is faulted.

[max2k]

This wasn't a single zap type of shock.. it was a continuous tingling as we were holding the panel wrapped in the blanket and didn't cease until we put the panel down. We both felt the same sensation.

It is not possible for 30-40V DC to do what you describe: assuming both of you were holding panel frame with your bare hands the part of frame between your hands would simply prevent any voltage difference.

[max2k]

Not me, I would box it up. I already know it is faulted.

My understanding is they simply lifted panel off the pallet and got shocked, the panel was not touching array. Unless OP has lonely high current AC power wire passing nearby as Mike suggested I don't think it is possible to get shocked from the panel voltage even if one of its leads developed short to the frame, there's just no path for that current to return to the other lead.