Wiring the bank

Surfpath

Been busy receiving most of the solar gear.

Quick question. I notice that my battery supplier shipped cabling to wire my eight battery (each 6 volt) 370 amp hr bank as below:

In essence I desire a 48v 370amp hr battery bank. Is this the best way to wire it?

Thanks! - SP
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BB.

Re: Wiring the bank

Yep--Electrically that is how you would connect them.

Physically, you can arrange them in 1x8, 2x4, 3x3 (with one blank space) or such to match your shelf/floor/box space.

In your case, you want to keep the batteries cool (warm island?), so you want good air circulation around them (especially if you have good sized loads/solar array/charging sources). A 1x8 array would be best in this case for cooling/air circulation.

-Bill

Surfpath

Re: Wiring the bank

BB. wrote: »

Yep--Electrically that is how you would connect them...A 1x8 array would be best in this case for cooling/air circulation.

-Bill

Cool. Thanks Bill. Yes, I can do 1 x 8.

Here's another twist (given the space constraints). If I go 1 x 8 the first battery in the string would be -mostly- underneath where I plan to mount my inverter/controller. I have heard it's not advisable to have this. Although the NEC does not apply in my case, any recommendations?

The solar room is very well ventilated. I was thinking of making a hinged battery "top" to go over the batteries that would have a vent to the outside. I have some acrylic that I can use on said top so that I can easily keep an eye on the batteries as well. It'll also help to prevent dropped items from touching the wiring and terminals.

BB.

Re: Wiring the bank

Yes, if you can keep the gases and (a little bit) of acid mist vented to the outside (you might want to look at battery caps designed to filter acid droplets from battery gases)--That would be a help (on an island, you probably already live with the salt air slowly eating up anything nice--I lived/worked on the Pacific coast coast for many years).

More or less, the nothing in front of the electrical box is to provide safe and easy access to your wiring/controllers/etc... Keeping them away from the battery fumes and not dropping tools on the battery bank is a plus too.

Covering the battery bank and/or placing it in a locked (kid/visitor resistant) room is also a help for safety. Anything that can go wrong, will go wrong.

Personally, large battery bank scare me--So would make sure you have a fuse/breaker/disconnect (and/or even a fire ax) near by so that you can turn off the battery bank in case something goes terribly wrong (having an accessible disconnect access on the outside of the building is also not bad--firefighter/neighbor/spouse can pull the battery power disconnect in an emergency--as long as kids/others don't cause you difficulties).

Also, I believe in separating generator/fuel supply from battery/solar shed too... Again anything that can go wrong will (fuel line fails, gravity feed/electric fuel pump keeps providing fuel to feed a fire, etc.). Fire detection and some sort of automatic fuel shutoff near the supply, etc... All can reduce the chances of a single failure taking out your entire power installation (or even home).

-Bil

One other thing to think about (yea--fire risks are always top in my worries for power systems)--Insulation when overheated will sustain burning very nicely (fire resistant plastics are not fire proof). If your wiring is exposed, mounting on sheet rock/cement backer board, metal sheet/screening for your electronics/breaker boxes is important (everyone is really tempted to just put up a a 4x8 sheet of plywood and screw everything too it.

Also, if you have your batteries under your exposed (not in metal boxes/conduit) electronics/wiring, it would be a good idea to put a metal shelf or screen under the installation to catch buring/dripping plastic from landing on the battery bank (or a flamable subfloor).

-BB

Vic

Re: Wiring the bank

Hi Surfpath,

Glad that you have your new battery bank.

If a 2 X 4 layout can be accommodated, this can often shorten the battery-to Inverter cables. This also places the maximum potential of the battery bank closest together, which some do not like, but this layout for single strings on a 48 V bank has worked well for me. A battery box with a hinged lid is nice, although there is a reasonable amount of heat dumped into the bank, especially in the Absorb and EQ stages, so the cover can trap this heat. Many trade-offs. Good Luck, Vic

Surfpath

Re: Wiring the bank

Vic wrote: »

Hi Surfpath,

Glad that you have your new battery bank.

If a 2 X 4 layout can be accommodated, this can often shorten the battery-to Inverter cables. This also places the maximum potential of the battery bank closest together, which some do not like, but this layout for single strings on a 48 V bank has worked well for me. A battery box with a hinged lid is nice, although there is a reasonable amount of heat dumped into the bank, especially in the Absorb and EQ stages, so the cover can trap this heat. Many trade-offs. Good Luck, Vic

Hi Vic,
Below is a picture of my power panel & batteries. I am now thinking that a 2 x 4 setup may be best. It will ensure that none of the batteries fall directly beneath the panel. I will still install a battery "top" for them though.

I'm now looking for wiring plans to see how to accomplish this, but if you have a diagram or photo of how you did yours that would be great.

Ideas and thoughts from others regarding how this set-up is going would also be appreciated.
-SP
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Surfpath

Re: Wiring the bank

Something like this do the trick?

Vic, I get what you say about the final (+) and (-) being much closer in this instance (than in the longer 1 x 8 set-up). As an aside, I plan to mount a 100 amp battery terminal fuse on my terminal (+) post - don't know if that makes a difference.

Also I notice that a lot of folks seem to conduit their battery cables, including the 'terminal' runs. Would you recommend this? Or, would you have them run loose up into the panel where they are bolted?

BB.

Re: Wiring the bank

A fuse/breaker at the battery bank and a conduit for cable run from battery bank to epanel add protection. Capturing the base of the batteries/battery straps if you have earthquakes can help too...

Many people (me included) tend to treat our solar power systems as "hobby" systems where we plan on working on/around them "all the time"...

In reality, if you do this right, you should not need to worry about working on the system--Other than doing battery maintenance.

Anything you can do to keep the system "safe" from natural and human caused problems, will be a big help for long term reliability and safety.

If the system is in an exposed area (say back wall of a garage) vs a locked utility room may also enter into how much "protection" you want to add.

-Bill

vtmaps

Re: Wiring the bank

Surfpath wrote: »

Something like this do the trick?

Yes. I did mine that way so that my battery cables would be as short as possible.

Surfpath wrote: »

As an aside, I plan to mount a 100 amp battery terminal fuse on my terminal (+) post - don't know if that makes a difference.

Excellent idea. I plan to do the same next time I have an insulated wrench in my hand. I am planning to put my fuse in the middle of the series string of batteries. (in your diagram that would be on the right side). It doesn't matter where in the string you put the fuse.
--vtMaps

Vic

Re: Wiring the bank

Hi Surfpath,

Nice drawing! Yes that is just what I was trying to say. This has worked well and allows 5-foot inverter cables here. Battery box should help in a number of ways, and conduit also helps. And, a separate conduit for the Battery Temp Sensors, plus any other monitoring or control cables is very good. Here there are far too many rodents. They love to eat cables and wiring. Have seen neighobr's systems where the BTS cable gets eaten through -- often more than once.

The Power Rooms here are in steel Cargo Containers, which are quite tight, unless doors are left open over night for ventilation. The batt box and conduit helps portect all of the cableing.

Good Luck with the new bank. HNY Vic

Surfpath

Re: Wiring the bank

OK, I'll have the battery bank wired soon. I will also finish wiring the generator tonight to the AC in portion of the Flexpower panel. Here is what I am thinking off the top of my head (any questions and uncertainities will be typed in bold). Hope someone can address these & my fears

Grounding before I start:

Grounding the Generator (Yamaha 6300ISDE): I will use the generator lug located on the genny itself to ground it to a rod located outside the solar room (15 feet length using 10 AWG wire).

Grounding the FP panel: I will connect the AC ground wire which runs out of the top of the Flexpower panel (the one that goes directly to the main house ground which is located 50 feet away from the solar room), to ground the FP panel (also grounds the generator, right?).

Grounding the bank: I will run a ground wire from the battery bank (how do I attach it to the bank?) to the DC ground bus bar on the flexpower panel. I will then run a DC ground wire out and connect it to the same grounding rod (that the genny is connected to) located directly outside the solar room.

I will then switch on the battery bank breaker to power up the panel, program in the specific Trojan Charging settings in the Mate, start my generator and then request the mate to perform an EQ [??].

The big plug on my Yamaha 6300 says "30" on it (presume 30 amps), so I believe it can kick out power in this range. Any idea how long it will take to EQ my bank?
(I'm expecting a pretty long time. I know panels do a better job of finishing off any battery charge - but I still have to install my panels).

The SG's on each of my 6v batteries (48v 370 amphr bank) were around the 1.250 mark a few days ago (some a click above 1.250, some were 2 clicks below on my turkey baster SG).

Either way I believe it will be beneficial to get a charge in.
Phew...hope this all works OK.

Flexpower ground map provided FYI
Attachment not found.

BB.

Re: Wiring the bank

Surfpath wrote: »

Grounding before I start:

Grounding the Generator (Yamaha 6300ISDE): I will use the generator lug located on the genny itself to ground it to a rod located outside the solar room (15 feet length using 10 AWG wire).

Assuming this is over a ~3.5 kW genset, there is a good chance that there is an AC Neutral to Earth Bond in the genset... You either need to lift the bond inside the generator or confirm that the AC Inverter has a three terminal AC transfer switch (L-N-L; or two terminal if 120 VAC inverter) so you don't end up with two connected earth to neutral bond points (causes AC current to be shared between neutral and green wires).

Grounding the FP panel: I will connect the AC ground wire which runs out of the top of the Flexpower panel (the one that goes directly to the main house ground which is located 50 feet away from the solar room), to ground the FP panel (also grounds the generator, right?).

Normally, yes. Assuming the main house ground is near the AC mains panel (and drop from pole). If the ground rod is not next to the AC main panel--You may wish to consider moving/adding a main ground rod near the main AC panel--especially if you live in a lightning prone area--I much prefer to not bring "lighting energy" into the home, but down the wall to a ground rod right at the base of the wall.

And that gets back to the drawing showing the solar panel frame grounding going into and back out of the combiner box and into, eventually the epanel/charge controller. I would suggest to drive a ground rod next the solar panel array (if not near the main ground rod) and bring the grounding wire (typically 6 awg recommended here) from the panels directly down to the ground rod. And if you have the combiner box there, bring a second ground wire from the box directly the local ground rod (note--NEC has very specific requirements for grounding, using conduit around ground wire, etc.---You should comply with those requirements too).

Personally, I would like to bring a separate ground wire from the remote ground rod back to the main house ground rod... This prevents a short circuit in the solar array/metal structure from being energized relative to the rest of the home/AC/DC grounding.

Grounding the bank: I will run a ground wire from the battery bank (how do I attach it to the bank?) to the DC ground bus bar on the flexpower panel. I will then run a DC ground wire out and connect it to the same grounding rod (that the genny is connected to) located directly outside the solar room.

DC grounding is a big issue... I don't agree with everything in the current NEC (the use of a DC GFI breaker/fuse system). But--Anyway, the ground wire from the battery bank usually goes from the DC Ground bus common point directly to the main ground rod (you don't want parallel grounding paths on AC or DC side--DC especially because the currents may be upwards of 10x the amperage of the AC circuits).

Regarding the generator--Again, question of AC neutral to earth bonding. You only want that done in one location, or use a muti-pole AC Transfer switch to isolate the different AC Neutral bonds.

And, I would suggest running the AC safety ground from the genset to the AC Main Ground. I would only drive a local to generator ground if there is a danger of lighting strike and/or it is in an outbuilding (metal roof/pipes/etc. that you can ground).

You want the AC Green Wire to connect all electrical systems together so that if there is a short circuit to grounded metal, that it will pop the circuit breakers/fuses. If you only use a local ground rod (one in home, one at generator), there is usually too high of resistance to reliably trip a 15 to 200+ amp circuit breaker.

I will then switch on the battery bank breaker to power up the panel, program in the specific Trojan Charging settings in the Mate, start my generator and then request the mate to perform an EQ [??].

First, assign each battery (cell) a number. And log the specific gravity and voltage of each cell/battery as it came from the warehouse. If the any of the cells are less than ~75% state of charge and/or have sat for a month or more without charging (flooded cell), you may have problems with the battery(ies).

Next, set up the charge controller(s) for the voltages/current levels that Trojan recommends (absorb timer should be in the 2-4 hour range for now). And charge the battery bank.

Next, measure the specific gravity of each cell... If the specific gravity difference between low and high cells is >~0.015 to 0.030, you can run an equalization charge. Basically set the charger to equalize (typically around 15.0 to 15.5 volts for a 12 volt bank and no more than ~5% charging current of bank's AH capacity). Measure the specific gravity every 30-60 minutes. And when the SG stops rising on all cells between readings--stop equalization, and log the temperature corrected specific gravity for each cell--That is your 100% state of charge reading.

The big plug on my Yamaha 6300 says "30" on it (presume 30 amps), so I believe it can kick out power in this range. Any idea how long it will take to EQ my bank?
(I'm expecting a pretty long time. I know panels do a better job of finishing off any battery charge - but I still have to install my panels).

Probably somewhere around 20-25 amps continuous current at 240 VAC. Some generators could be configured for 40-50 amps at 120 VAC--but not many. So, your battery charger's input rating and how you connect it to your generator will setup some more limitations (i.e., if 120 VAC charger, then a maximum of ~20-25 amps at 120 VAC). Note that the NEC requires that all circuits be 1.25x the maximum continuous current. So for a 30 amp branch circuit * 1/1.25 derating = 24 amps maximum continuous current allowed.

Oops--Checked, you are on a 230 VAC @ 50 Hz island, so there is no issue about the 115 VAC performance/splitting of the power between 115 volt legs. Also, you may or may not have a AC Neutral to Earth Bond... You will have to let me know what your electrical wiring standards are.

The SG's on each of my 6v batteries (48v 370 amphr bank) were around the 1.250 mark a few days ago (some a click above 1.250, some were 2 clicks below on my turkey baster SG).

Using the Trojan user manual (PDF):

http://www.trojanbattery.com/pdf/TRJN0109_UsersGuide.pdf
Trojan Battery User's Guide (Spanish)

1.250 SG is roughly 85% state of charge. A 370 AH @ 48 volt battery bank would need:

370 AH * 15% state of discharge = 55.5 AH

Say you have a 25 Amp battery charger (I am not sure I saw your's rating):

55.5 AH / 25 amps = 2.22 hours

And add 2-4 hours at "absorb" voltage to bring the bank to near full charge (slowly reducing charging current to eventually 1-2% of bank AH capacity). At that point the battery is full and you can stop charging.

Regarding EQ--As I recall Trojan recommends equalization when the high/low cell spread is >0.015 or 0.030 ... If yours is less, you don't have to equalize. How long to equalize--probably 1-3 hours--But it depends on your equalize current/voltage and how far apart the readings are. Equalizing is hard on the battery bank and you do not want to do it too much (erodes plates, oxidizes positive plate grid, etc.).

Some vendors recommend EQ'ing every month or two, and other vendors recommend every 6 months. Let the manual and your experience be your guide.

Either way I believe it will be beneficial to get a charge in.
Phew...hope this all works OK.

Sounds like you are off to a good start--And you have a received a good set of batteries (no read flags). As always, check electrolyte levels before charging--Plates covered (never exposed to air). Only add distiled (or filtered rain water) after charging/equalization (gassing batteries and elevated temperatures raises electrolyte levels--you don't want electrolyte forced out of fill holes).

-Bill

vtmaps

Re: Wiring the bank

As you begin battery charging on your new system, one thing to watch out for is battery temperature (you're on a warm island).

I presume that you have a remote battery temp sensor. On your shakedown cruise you need to make sure that it is properly functioning. It can prevent 'thermal runaway' which may destroy your batteries and their surrounding environment.

As batteries warm up they accept more current for a given voltage. The temperature compensation in your equipment will reduce the voltage as the batteries warm up. Use a digital voltmeter to make sure that is happening.

--vtMaps

Surfpath

Re: Wiring the bank

Howdy,
Yes, this Flexpower came with a RTS (battery temp sensing probe). It will be installed shortly.
Bill, thank you for the indepth and informative reply.

I realize that grounding is an indepth and periodically confusing concept, so I appreciate your insight.

From another forum (Australian) regarding my Yamaha generator [a 230v 50hz model]
I found the following information in a Yamaha document regarding Yamaha inverter generators. EF1000iS, EF3000iSE, EF3000iSEB have floating neutrals. EF2000iS, EF2400ISHC, EF4500iSE, EF6300iSDE have bonded neutrals.

Looks like I will have to find that neutral to earth bond in the genny and take it out.

Yes the batt EQ's look O.K, but they have been in transit for ~ a month now. SO I am trying to get all of this other stuff sorted out so I can charge em.

Still not sure whether I have to do a regular charge or an EQ [they seem to be all around 1.250 apart from 3 with variances of either +001 or -.002].

I thought all new FLA banks around the 80% mark should be EQ'd upon first startup?

Also when I ask the mate to perform an EQ does it go straight into hard charging mode (and is that OK?).
I love this forum, I really do.:roll:

Vic

Re: Wiring the bank

Hi Surfpath,

Regarding EQ, believe that Trojan recommends an EQ upon commissioning a new bank. It is best if an EQ is performed after the Absorb stage is completed. EQ voltage should be temperature compensated. Am unsure that the FM series of CCs does this. It would be best if the RTS is attached mid-way down the side of one of the batteries.

The EQ should be an hour or more. Would suggest that the EQ voltage be in the lower to mid-range of the voltage recommended by Trojan. Would guess that this voltage would be about 62.5 - 63 volts. If the bank is warm, this voltage should be reduced by about 0.75 volts or so.

Good Luck, And the suggestion of numbering each battery with a felt-tipped pen, is a great one. And Log the incoming SG of each cell and resting voltage of each battery in your Battery Log book. Have Fun, Vic

Surfpath

Re: Wiring the bank

Vic wrote: »

Hi Surfpath,
And the suggestion of numbering each battery with a felt-tipped pen, is a great one. And Log the incoming SG of each cell and resting voltage of each battery in your Battery Log book. Have Fun, Vic

Nice tips about the EQ Vic, I appreciate them. To the experienced, installing a pre-wired panel may seem mundane. To me it's still a little challenging. I'm perhaps overly cautious b/c it's hard & expensive to get gear to me, and (safety speaking) emergency medical care is limited.

Yes, I numbered each battery and cell. My log has started.

After sorting out the genny's neutral-earth bond I will turn on the battery bank, start up the sytem/mate, input the bank paramaters and Trojan set-points (modified very slightly as you recommend), and then after an hour of float, ask the system to perform an EQ (for 'about an hour or so'), Monitor the SG's of the batts and look for 1.277 or around that.

With the Trojan L16REB's I realize the importance of a solid charge. RNGR275 has documented some of his experiences on this forum, and at midnite's. All useful for me to reference. Thanks!

Vic

Re: Wiring the bank

Hi Surfpath,

You do not need to spend any time in Float before EQing. Float is just to maintain a fully charged state for the batts. Ideally, you would start the EQ just at the end of Absorb. You could even cheat a bit, starting EQ a bit before the end of Absorb.

Sounds like you are doing fine. Asking before doing is a very good way to start with a new system.

Have Fun! Vic

Surfpath

Re: Wiring the bank

Sorry, I meant "absorb" instead of float. Thanks for the correction.

Surfpath

Re: Wiring the bank

Update on the generator neutral unbonding.

I have looked around the web for directions on how to accomplish the above on my Yamaha6300isde. No such luck so far. I haven't opened up the generator to see if it is a simple thing, however I have heard that this may be a complex procedure.

Seeing that I am just trying (for now) to -only- charge my batteries using the generator until my panels are up, could I not just temporarily remove the Flexpower panel's neutral to earth bond? When my panels are up and I attach my AC house wires I can reattach the bond, and sort out the genny's bond.

The flexpower ground map above may be a good reference.

Aside: I have looked at the 2 electrical panels in my house and neither appears to have a ground to neutral bond. A local electrician said that the N-G bond exists in 'the grid," and that's why my house was not wired with one. Does this make any sense? By the way my house is not grid connected at all.

BB.

Re: Wiring the bank

At least in the US, the neutral bonding actually occurs in two places (as I understand). One is at the utility pole where they ground bond the neutral of the transformer... And the second place is at each home's main panel to local earth ground (water pipe, ground rod, etc.).

In and of itself, having multiple grounding to earth is not the end of the world. Where is becomes a problem is:

First, you can get a split of current flow between the green wire and the white wire (parallel white and green connections, shared current between the two wires). If the green wire is at least as heavy as the white wire (and rated for application)--It will work.

The "problem" becomes several... First, if you have a GFI outlet on the genset, the parallel current flow through the plug will pop the GFI breaker/outlet. Another is if there is a broken white wire connection some where, the green wire now carries all current and nobody will notice the white wire connection has failed--So no "backup" safety ground.

The solutions:

Leave it all connected... Don't use GFI outlets on the genset (will work, sort of safe, could cause generator electronics/electrical problem--have been reports of other brands of generators that have IVR electronics fail because of ground currents).

Disconnect neutral bond at genset. Optimum solution, but may not be easy (depends on generator mfg.).

Lift neutral at Epanel--Need more information about transfer switch/inverter/wiring configuration to say much. Generator will provide neutral ground--But I am not sure how your generator/AC inverter setup is wired anyway--Don't know if neutral from genset is switched or not.

Install a two (120 volt) or three (120/240 volt) pole AC transfer switch. That way, you can have both neutral-earth bonds, but the AC transfer switch will "isolate" the two from each other (may already be wired this way in epanel or your inverter--that is why need more information).

Anyway--Let us know what the details of the epanel/ac inverter setup is...

-Bill

Cariboocoot

Re: Wiring the bank

Whatever you do, don't hire that electrician.
The fact that the Neutral (center tap) of a line transformer is connected to ground does not make up for the N-G bond in the house.

The problem you are facing is not that there are two N-G bonds so much as the potential for the two to create a ground loop. There's an easy way to avoid it; don't ground the generator to Earth. Then the only loop potential is between the generator and the N-G bond at the Flexpower panel. As this will (should) be a closed circuit with no feeds to any other devices there really isn't a problem anymore (providing the gen output does not have a GFCI on it).

Surfpath

Re: Wiring the bank

The generator neutral bonding question is a confusing one.

I have tried to sort it out in my head & in doing so I came across these more helpful posts...
....
EDIT
Upon second thought I removed these posts, they did not appear to clarify the situation at hand..

Surfpath

Re: Wiring the bank

BB. wrote: »

At least in the US, the neutral bonding actually occurs in two places (as I understand). One is at the utility pole where they ground bond the neutral of the transformer... And the second place is at each home's main panel to local earth ground (water pipe, ground rod, etc.).
...
The solutions:
-Leave it all connected... Don't use GFI outlets on the genset (will work, sort of safe, could cause generator electronics/electrical problem--have been reports of other brands of generators that have IVR electronics fail because of ground currents).

-Disconnect neutral bond at genset. Optimum solution, but may not be easy (depends on generator mfg.).

-Lift neutral at Epanel--Need more information about transfer switch/inverter/wiring configuration to say much. Generator will provide neutral ground--But I am not sure how your generator/AC inverter setup is wired anyway--Don't know if neutral from genset is switched or not.

-Install a two (120 volt) or three (120/240 volt) pole AC transfer switch. That way, you can have both neutral-earth bonds, but the AC transfer switch will "isolate" the two from each other (may already be wired this way in epanel or your inverter--that is why need more information).

Anyway--Let us know what the details of the epanel/ac inverter setup is...

-Bill

I hope my research post above doesn't confuse the problem at hand.
Bill, as usual, you bring up some good items. Let me try to answer.

I am pretty sure my generator does not have GFCI outlets. It just has a 'big' 30A lockable plug and a small 15A regular outlet. It is the non-US version of the Yamaha, I guess. Let me try to post a picture.

I have no transfer switch installed. My Flexpower panel allows me to attach a generator (a la grid, I guess) in the AC in. There is an AC in breaker on the panel (I am very sure). I will try to include a better diagram of the panel.

More pics to follow.

Surfpath

Re: Wiring the bank

Photo of US Yamaha 6300 ISDE
Attachment not found.
Photo of my Yamaha 6300
Attachment not found.

Dont see any GFCI plugs on my unit.

Other points I know for sure:

-my flexpower definately has a GFCI installed in it.
-my flexpower panel definately (currently) has a neutral to ground bond

Cariboocoot

Re: Wiring the bank

Where you get into trouble with GFCI is when you have the N-G bonds on both the input and output side of it. The GFCi looks for current imbalance between Hot and Neutral, and having the 'dual bond' allows some of the current to be carried on the ground wire instead of all of it on the Neutral. That will cause the GFCI to trip.

Otherwise without the gen ground at the gen the Neutral and Ground wires will act as the same wire. The only danger here is that the chassis of the generator becomes Neutral and will be not be safe to touch. Except that the N-G bond at the Flexpower panel should negate the problem.

In my opinion there is very low risk of danger from this connection. It is essentially the same as my system with the Honda EU2000i (which has no Earth ground at the generator) and the N-G bond at the AC distribution panel. Works fine and the outlets all check out okay. There is no GFCI anywhere on my system. nor would I be keen to have one; more trouble than it's worth in my opinion. And yes I do put them in for home installs. Sometimes have to replace them when the inexplicably burn up with no load on them too. :roll:

Surfpath

Re: Wiring the bank

AC in & neutral to ground info from the Flexpower manual (sorry if the print is a little fuzzy, I had to make them images):
Attachment not found.
Attachment not found.

vtmaps

Re: Wiring the bank

Surfpath, Your system has two ground rods. If lightning strikes in your neighborhood, your two ground rods could be 1000's of volts apart. Bill gave you some good advice in a previous post in this thread, but it may have gotten lost in the massive amount of info. I will quote it so that it gets the attention it deserves:

BB. wrote: »

Personally, I would like to bring a separate ground wire from the remote ground rod back to the main house ground rod... This prevents a short circuit in the solar array/metal structure from being energized relative to the rest of the home/AC/DC grounding.

I think a good way to do this is a very heavy bare copper wire buried in a ditch between the two ground rods.

--vtMaps

Surfpath

Re: Wiring the bank

VT,
Thanks. Yes, I registered BB's advice (ie the wire in the ditch between the two rods...in our case the current house rod is on the opposite sid of the solar room ). When I told my wife she said, "what another #$$%@ ground wire!!"

Instead of the ditch and heavy copper wire to 2 rods, we are thinking of rerouting the house ground wire (and rod if we can dig it up) to one ground rod location on the side of the solar room.

This ground rod location (also in nice, moist soil) can more conveniently service the other proposed grounding wires. Like the...

-panel ground (panel ground wire directly to ground, as BB said)
-The PV combiner box (directly to ground - really?-like BB said)
-Flexpower DC ground (ie the battery ground)
-The generator terminal ground (this one might be a little excessive)

Attached is a proposed ground map.
It seems pretty crazy to have all these wires though (very $$). Your help in economizing these runs would be appreciated. :-)
Attachment not found.

vtmaps

Re: Wiring the bank

Surfpath wrote: »

It seems pretty crazy to have all these wires though (very $$). Your help in economizing these runs would be appreciated. :-)

In your diagram wires F-G-E could make a ground loop, I'm not sure because I've lost track of the bonding situation. Where are your neutral-ground bonds? Are you breaking the bond in the generator?

Also, to economize you could have a ground bus bar at the solar room and have a single run to the ground rod to replace D-E-F.

Surfpath wrote:

The PV combiner box (directly to ground - really?-like BB said)

Really. If you have your feet on the ground and you touch the combiner box, you want the box to be at the same voltage as your feet. Best way to do that is to ground the box to a ground rod that is near your feet.

--vtMaps

Cariboocoot

Re: Wiring the bank

Surfpath;

You've got some redundant wiring in that diagram. It is not necessary to carry a separate ground wire from each device to the ground rod. Certain grounds can be common without any difficulty.

The panel frame/mount ground should go directly to the rod, without entering the house.
The ground of the combiner box would connect to the AC and DC grounds of the Flexpower, where the Neutral-Ground bond is and then to the ground rod.
The generator's wiring with its N-G bond would connect to the AC side of the Flexpower via the transfer switch. You have no GFCI on the generator output so there should be no problem there (ground loop is contained). If there is, leave out the ground wire from the gen to the Flexpower and let it "float".

The more ground wires you run the greater the chance of creating a ground loop, which is what you don't want.

The basic intent is that the actual ground wires should carry no current during normal operation; they are there for if something goes wrong with the other wiring.

BB.

Re: Wiring the bank

Like vtMaps said--one safety ground from outbuilding/garage to main ground rod (moving and/or installing new ground rod seems like it may be a good idea). You might find pulling the old rod difficult.

Regarding the combiner box--I am a big believer in not bringing solar array ground into the home if you have a good chance of lightning strikes. Direct to ground at the base of the panels is a better idea. The ground wire (in trench) from panel ground rod (if you have one) to main ground rod is for the normal AC/DC safety ground so that a short from wiring to ground will pop a fuse/breaker).

-Bill