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Author Topic: Earthing Solar Panels on a Steel Barge, with Victron and SMA?  (Read 6475 times)
al barge
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« Reply #30 on: April 02, 2015, 05:37:04 PM »

..for my 0.02 worth, I'd DC couple them.
So it's DC to battery and AC on demand to loads. I can't see it being more efficient to invert the entire PV output to satisfy the base load and then rectify it back to DC to charge the batteries.

I'll have to look through some Outback etc manuals to see how they deal with grounding.

In the fronius Galvo manual they show if the panels need grounding, it can be done in the inverter, I assume as it is galvanically isolated from the AC this is a safe bet, although "The inverter's insulation monitoring must be deactivated when the solar modules are grounded"

Maybe class II modules with any type of MPPT which monitors things is safe enough? How clever are Outback/midnight/morningstar? as without galvanic isolation but high panel capacitance, i'd guess there could be stray currents with differential ground potential on the Hull?

 Huh







* Fronius panel grounding.JPG (18.94 KB, 385x246 - viewed 268 times.)
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38m Belgian Spits Barge, Victron Multi 24/3000/70-16, 420Ah (c5) Used Forklift Batts, Smartgauge, DIY wood Stove, DIY diesel drip stove heat exchanger circuit, Spare roof space..
al barge
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« Reply #31 on: April 02, 2015, 05:55:07 PM »

need a bigger barge.   Grin

It's never big enough! Cheesy How did you go about grounding Billy?


Quote from: Scruff
"What about a 24VDC workshop?"

Don't think Festool make any 24v kit, and my shop vac and dust extractors might run a bit slow! I like the battery though Smiley


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38m Belgian Spits Barge, Victron Multi 24/3000/70-16, 420Ah (c5) Used Forklift Batts, Smartgauge, DIY wood Stove, DIY diesel drip stove heat exchanger circuit, Spare roof space..
Scruff
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« Reply #32 on: April 02, 2015, 05:55:17 PM »

In the fronius Galvo manual they show if the panels need grounding, it can be done in the inverter, I assume as it is galvanically isolated from the AC this is a safe bet, although "The inverter's insulation monitoring must be deactivated when the solar modules are grounded"

Could be centre tapped. Best be sure.

Maybe class II modules with any type of MPPT which monitors things is safe enough? How clever are Outback/midnight/morningstar? as without galvanic isolation but high panel capacitance, i'd guess there could be stray currents with differential ground potential on the Hull?

Hard to say without sticking an O-scope to yer hull.
They're pretty clever, I use a TriStar for everything mains/PV/alternator I've never seen a better charger. I'd go midnight for MPPT though. Never had to worry about galvanic corrosion myself so I've never looked for it.
Surely the differential PD is only an issue if you multiple bond?
Sorry I'm not much help but interested all the same.

I don't know if this is any interest to you. Looks like the isolated small scale version still requires PME earthing of a kind and I'm not sure what to make of that dashed capacitance between earths
http://www.bender.org/documents/Solar_brochure_NAE1111041.pdf
« Last Edit: April 02, 2015, 06:14:28 PM by Scruff » Logged
Scruff
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« Reply #33 on: April 02, 2015, 05:59:16 PM »


Don't think Festool make any 24v kit, and my shop vac and dust extractors might run a bit slow! I like the battery though Smiley

Makita do, cheap as chips second hand without the battery because them li-ions are too expensive to replace.  Grin

One step at a time doesn't have to be exclusively one voltage or another (as long as they have different plugs).
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al barge
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« Reply #34 on: April 02, 2015, 06:27:33 PM »


Makita do, cheap as chips second hand without the battery because them li-ions are too expensive to replace.  Grin

One step at a time doesn't have to be exclusively one voltage or another (as long as they have different plugs).

I already have a nice grey and green collection, (dangerous statement alert!) going back to throw away blue would be a cardinal sin i vowed never to do again over 10 years ago..

I'll have a gander at the Bender pdf, thanks!

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38m Belgian Spits Barge, Victron Multi 24/3000/70-16, 420Ah (c5) Used Forklift Batts, Smartgauge, DIY wood Stove, DIY diesel drip stove heat exchanger circuit, Spare roof space..
Billy
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« Reply #35 on: April 02, 2015, 06:44:56 PM »

All 24V negs go to earth stud, as do earths from Victron, and all other stuff that needs earthing.  Isolation trans if we have shore power.  Frames and mount for PV earthed to studd.  PV runs are 70V ish not 600V so no worries there I hope.   Grin  My Rolls are nearly ten year old and seem fine and I try not to go below 85% charge.
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al barge
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« Reply #36 on: April 02, 2015, 06:52:09 PM »

All 24V negs go to earth stud, as do earths from Victron, and all other stuff that needs earthing.  Isolation trans if we have shore power.  Frames and mount for PV earthed to studd.  PV runs are 70V ish not 600V so no worries there I hope.   Grin  My Rolls are nearly ten year old and seem fine and I try not to go below 85% charge.

Are your panels classII insulated, and you chose to bond, or did they say they needed bonding? No chance our batteries will last 10 years @ 50-40% DOD, but they got us on the road (water)  Wink
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38m Belgian Spits Barge, Victron Multi 24/3000/70-16, 420Ah (c5) Used Forklift Batts, Smartgauge, DIY wood Stove, DIY diesel drip stove heat exchanger circuit, Spare roof space..
Billy
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« Reply #37 on: April 02, 2015, 09:15:04 PM »

No idea about class II but the panels are Navitron Yingli for domestic roof installation.  It was suggested that it might be prudent to earth the frames as  it is a convoluted passage to the steel of the boat.  All that effort to insulate the engine and equipment from the stucture of the boat and the surveyor wants the battery negs bonded.    facepalm  Heyho.

I did wonder about AC coupling but it's not worth it for me as I don't have the area of PV.  I'll stick with what I've got and know.  Well a little bit anyway.
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rogeriko
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« Reply #38 on: April 02, 2015, 09:28:39 PM »

If you connect the panels directly to the batteries you dont have to earth them at all.  Does your generator have an earth rod or is it just plugged into the boats. If it is not grounded then the whole system is floating and you dont have to worry about galvanic corrosion or earthing panels or anything actually. Is the neutral connected to the ground anywhere in the system? Do you have RCD's and do they work if you touch live and ground together? I do not understand this obsession with bonding the panels, just choose the most efficient way of connecting them to the batteries first and then if they are all bolted together on a metal frame thats it job done.
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Nickel2
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« Reply #39 on: April 02, 2015, 10:06:21 PM »

... If it is not grounded then the whole system is floating...
I think that applies to a lot of barges!

 If one side of the PV array was connected to the keel, and there was a fault with the shore generator earthing spike, (or it wasn't earthed), the possibility arises of a  few hundred volts DC between generator chassis and the earth you stand on, that could push several hundred milliamps where they were not wanted.
My remark about Anodes was more concerning the possibility of a DC fault between the steel hull of the boat being at a different level to the soil ground, so that every time the sun shone, the anodes would sit there fizzing until they were gone.

N2
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1.140kW mono south-facing at 49*
EpEver 4210A at 24v
24V 400 Ah battery. (4x200Ah FLA)
EpEver STI1000-24-230 pure sine inverter
Of course it'll work. (It hasn't caught fire yet).
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