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nick5000 avatar image
nick5000 asked

Should the solar arch on my boat be grounded? I'm reading ~60V AC from the metal support

I have the Multi RS Solar on my boat that is connected directly to 5x550W solar panels in series. The Multi is grounded. The inverter AC output is connected to a breaker box. Even when all the breakers are turned off I can measure ~60VAC from the solar arch whenever the inverter is on. I sometimes feel slight electricity when holding the solar arch.

Why is the Mutli RS sending AC power out to the connected solar panels?


solarGroundingMulti RS
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2 Answers
Alexandra avatar image
Alexandra answered ·

@nick5000

It is possible induced voltage (capacitive coupling). Check with a low resistance/impedence meter. With alot of normal DMM meters often it reads a 'phantom' voltage. There is a fancy name for it. But I do know the meter type changes whether it is 'there' or not.

If you are able check the frequency of the AC voltage.

Real question is do you feel a tingle when you touch it. Or someone who is sensitive to those kinds of things? I know I pick up voltages where my husband does not.

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Alexandra avatar image Alexandra ♦ commented ·
On a different note. Make sure the voltage isn't being transmitted from actual AC lines through the boat.
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nick5000 avatar image nick5000 Alexandra ♦ commented ·
Thanks, yes AC out from Multi RS goes to a breaker box, when all the breaker are off there is still voltage on the solar arch. It disappears when I turn of the inverter (set Multi RS setting to charge only).
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nick5000 avatar image nick5000 commented ·

Thanks, yes I feel a tingle sometimes, if the deck is wet especially. Does that mean it's not a phantom voltage?

I used Mastech ms2108a

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Al avatar image Al nick5000 commented ·
Do you have a shore connection, fed through an Isolation transformer or galvanic isolator, and are your breakers protected by an RCD or GFCI?
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Alexandra avatar image Alexandra ♦ Al commented ·

Is the inverter properly grounded as well? Not interrupted etc.

You can get 'AC' voltages on but it is not actually AC but a combination of the capacitors and high frequency switching of the MPPT (or at least that is how I have understood it's cause). So feels like AC (hence the suggestion to check frequenc). Grounding them does help. I used to get that when I had a Phocos, had not noticed with the Multi RS, but then we have everything grounded now. I have no idea how that would work on a boat.

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nick5000 avatar image nick5000 Al commented ·
There is no shore connection, and the breakers doesn't have a RCD or GFCI. However this happens also when all breakers are off.
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Paul B avatar image
Paul B answered ·

I would suggest that the solar arch be grounded as a priority as this can cause lots of issues if you have a lighting strike or even a side strike, and it will also remove that tingly feeling you get sometimes. I would suspect that one of the panels maybe leaking to earth as you dont have any connections currently to the frame from what you say. anyway any metal structures above deck should be grounded.

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Related Resources

Mutli RS Solar Datasheet

Mutli RS Manual


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Ground, earth and electrical safety


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