Dock solar ground?

[dkyork]

Hey All,

Can't find much on this topic, but conflicting information. I'm installing a 6000xp on a boat dock with 4 solar panels feeding power. Do I need to ground the solar panels to something? Shore is 300' away and I've heard you don't need to ground out there over the water to I should run a 6awg copper wire to a rod on shore.

This is a complete off grid system. With the bonding enabled in the 6000xp, should I ground the solar panels to the breaker panel, inverter, or elsewhere?

Thanks!

 

[12VoltInstalls]

should I ground the solar panels to the breaker panel, inverter, or elsewhere?

That’s a different scenario yet the principle is the same. I don’t know specifically what EE’s might say, but if the water is not so deep I’d want to drive a rod at the dock that embeds into to river/lake bottom to ground the panels. While a large submerged aluminum plate should essentially do the same thing (make the panel frames at zero potential with the water/earth), there’s potential issues with galvanic degradation of a plate submerged in an electrolyte.

I would suggest looking up ABYC guidelines for grounding, bonding, and isolation of the 120/240VAC components as well. A floating or piling-supported offshore dock is essentially the same as a boat.

 

[JoeHam]

Note that fresh water is not conductive so Great Lakes vs ocean is a big difference. Fresh water will likely require a ground back on land.

I would probably run the ground back to land either way to be safe as I’m not aware of any real data for long term conductivity with copper wire in salt water but I would think corrosion would be a major issue.

I believe the solar panels and 6000xp need to be grounded at the same place.

 

[JoeHam]

You may want to consider installing the panels and inverter on land if protection from wind, waves, tides etc. is a concern.

Then you could run power out with plenty of safety resources available to guide you. Just one example :

Technical Bulletin: More Electrical Changes in Marina Code | Marina Dock Age

Editor’s Note: This article, thanks to expert Gary Loftis will explain the intent and purpose of the Tentative Interim Amendment (TIA) by National Fire Protection Agency (NFPA). It will explain the new definitions and how they impact marinas electrical systems; break down … Learn More

www.marinadockage.com

 

[12VoltInstalls]

te that fresh water is not conductive so Great Lakes vs ocean is a big difference. Fresh water will likely require a ground back on land.

I would probably run the ground back to land either way to be safe as I’m not aware of any real data for long term conductivity with copper wire in salt water but I would think corrosion would be a major issue

The purpose of grounding the panels is to be at zero differential with the earth surface which in this case is water. I don’t believe one would need to ‘ground’ on dry land to solve the issue at hand. Freshwater is less conductive than saline water due to electrolytic potential but it is still conductive.

You can still get galvanic action with freshwater

Check what ABYC has regarding grounding a boat and due that.

Related:

 

[JoeHam]

Fresh water is MUCH less conductive. I couldn’t even get Lake Erie to pop a breaker my 3kW inverter was powering when I dropped a live extension cord in.

See this old thread :

Fresh Water Conductivity and GFCI

So here is my latest display of stupidity: Last Friday I was up on top of a boat lift inside a metal boathouse. I was running an angle grinder powered by my 48v LiFePO4 through a 3KW inverter. I know this starts out like a @ghostwriter66 oilfield idiot story and I guess it is! As I moved...

diysolarforum.com

The videos linked in post 11 are entertaining and worth a watch.

 

[JoeHam]

@dkyork , are you planning to power your boat or a boat lift or a tiki bar with blenders and refrigerators or what on the end of your dock ?

The fact that you are installing a 6kW power system makes me think it’s to run more than your boat, but that’s just my best guess at this point .

 

[dkyork]

@dkyork , are you planning to power your boat or a boat lift or a tiki bar with blenders and refrigerators or what on the end of your dock ?

The fact that you are installing a 6kW power system makes me think it’s to run more than your boat, but that’s just my best guess at this point .

Lots of things, but the 6000xp is so cheap, it made sense to just get it. I mounted my solar panels yesterday on the boat house roof. Still waiting on cabinet to be built, so I can install the inverter and breaker panel.

Thanks!

 

[12VoltInstalls]

Fresh water is MUCH less conductive.

Yes. But the goal of “grounding” in this instance* is to put the panels at the same electrical potential as the surrounding earth which is in this circumstance is the lake water.

Question: would not it be sufficient to use a long grounding rod (3/4”x10’, $50) and drive it into the lake bottom? With a 6- or 4ga bare copper clamped to it that would be a great termination for panel grounding.

You wouldn’t really want the inverter to have any feedback potential so the current ABYC convention of an RCD - handling the inverter as if it were a separately derived system (it is) safely just like on a boat. That way electrolytic erosion won’t occur and all the safety protocols to isolate personnel from any possibility of becoming part of a circuit would be handled.

I don’t think running back to the onshore dirt offers any advantages to the panels, and perhaps it would not even be advisable to ground like a dirt-based independent system: just bond everything using marine protocols.

*FWIW department: freshwater is conductive enough that I use zincs (anodes) or other appropriate means to cause the effective voltage between the boat’s bonding system (fyi: not the same as N-G bonding) and freshwater to influence the effective voltage into a certain range that may sometimes make one’s salmon fishing activities more successful (by optimizing voltage range) or perhaps at least eliminate or minimize voltages that may be undesirable to fish.
So if freshwater is enough of a conductor to induce a small voltage that one can passively manipulate to an optimal range, it is sufficient to precipitate a voltage differential that creates an atmospheric discharge (lightning).

 

[JoeHam]

Looks nice, is that salt, fresh, or brackish water ?

I will defer to @12VoltInstalls here since I’m a self taught DIY’er (still learning) and his name suggests some level of professionalism.

 

[dkyork]

Looks nice, is that salt, fresh, or brackish water ?

I will defer to @12VoltInstalls here since I’m a self taught DIY’er (still learning) and his name suggests some level of professionalism.

I'd say brackish because I'm off the intercoastal Waterway in VA.

Appreciate all your help!

 

[dkyork]

Yes. But the goal of “grounding” in this instance* is to put the panels at the same electrical potential as the surrounding earth which is in this circumstance is the lake water.

Question: would not it be sufficient to use a long grounding rod (3/4”x10’, $50) and drive it into the lake bottom? With a 6- or 4ga bare copper clamped to it that would be a great termination for panel grounding.

You wouldn’t really want the inverter to have any feedback potential so the current ABYC convention of an RCD - handling the inverter as if it were a separately derived system (it is) safely just like on a boat. That way electrolytic erosion won’t occur and all the safety protocols to isolate personnel from any possibility of becoming part of a circuit would be handled.

I don’t think running back to the onshore dirt offers any advantages to the panels, and perhaps it would not even be advisable to ground like a dirt-based independent system: just bond everything using marine protocols.

*FWIW department: freshwater is conductive enough that I use zincs (anodes) or other appropriate means to cause the effective voltage between the boat’s bonding system (fyi: not the same as N-G bonding) and freshwater to influence the effective voltage into a certain range that may sometimes make one’s salmon fishing activities more successful (by optimizing voltage range) or perhaps at least eliminate or minimize voltages that may be undesirable to fish.
So if freshwater is enough of a conductor to induce a small voltage that one can passively manipulate to an optimal range, it is sufficient to precipitate a voltage differential that creates an atmospheric discharge (lightning).

Thanks much 12volt. Looks like gfcis are the way to go and I already planned on using all gfcis in my panel. I don't have a lot of circuits. Lights, outlets, 4 lift motors on 3 different circuits.

I wonder if afci/gfci are the way to go.

Appreciate your wisdom!

Dale

 

[12VoltInstalls]

his name suggests some level of professionalism

Ha! Fooled ya! LOL

Looks like gfcis are the way to go and I already planned on using all gfcis in my panel.

There’s some good info here.
If you treat it like a marine/boat mobile system it will be safe and dependable.