Inverter to Panel to Outlet??

ywhic · July 2012

I am leaning toward the Samlex SA-2000K-124 inverter..

It has dual NEMA 20 outlets with GFI.. as well as a hardwire terminal inside 8)

My proposed cabin panel will be fitted with say 8 breakers for various outlets in said cabin..

Inverter would be HARDWIRED into the cabin panel..

I was planning on keeping the neutral/ground un-bonded in this scenerio..

So 3 separate wires going to all points.. panel will have load (breaker), a neutral bar, and a ground bar..

(My cabin panel has a simple single ground/neutral screw that can be put in that would tie them together based on what you folks say)

Outlets will have 3 separate wires (as above).. I plan on putting GFCI outlets near the sinks and such..

No transfer switches.. just a straight wiring question..

AC Panel will be grounded, controller, battery, & inverter grounded.. (guessing to the same ROD??)..

Outside solar panels will be grounded to a ground rod outside near them..

(I've seen someone on YT tie their PV panels into the AC ground circuit by jumping a wire from the NEGATIVE side of there combiner box into a common GOUND block).. (not sure if thats good to do)..

Does all this sound correct??

vtmaps · July 2012

Re: Inverter to Panel to Outlet??

ywhic wrote: »

I was planning on keeping the neutral/ground un-bonded in this scenerio..
So 3 separate wires going to all points.. panel will have load (breaker), a neutral bar, and a ground bar..
(My cabin panel has a simple single ground/neutral screw that can be put in that would tie them together based on what you folks say)

So you will move the neutral to ground bond from the inverter to your panel? Sounds good to me.

ywhic wrote: »

AC Panel will be grounded, controller, battery, & inverter grounded.. (guessing to the same ROD??)..
Outside solar panels will be grounded to a ground rod outside near them..

This doesn't sound too good. I think that you are saying that you will have two ground rods, one for the equipment and one for the panels. You may be setting yourself up for some issues with lightning.

When lightning strikes nearby, the two ground rods may be thousands of volts apart. I think the solution is to bond the two ground rods with some buried heavy bare copper wire.

--vtMaps

ywhic · July 2012

Re: Inverter to Panel to Outlet??

Is there any other way to bring the GROUND from the solar panels into the building to the single grounding rod??..

Like I said some other person on-line JUMPED his negative lead from the panels at his combiner box to the same GROUND as everything else.. then just used 1 rod.. is the NEGATIVE lead in effect the GROUND anyway on panels???

Is the negative/ground bond required at all?? or is just a short cut most electricians take to bring the wire into the panel???

vtmaps · July 2012

Re: Inverter to Panel to Outlet??

ywhic wrote: »

Is there any other way to bring the GROUND from the solar panels into the building to the single grounding rod??..

Like I said some other person on-line JUMPED his negative lead from the panels at his combiner box to the same GROUND as everything else.. then just used 1 rod.. is the NEGATIVE lead in effect the GROUND anyway on panels???

Is the negative/ground bond required at all?? or is just a short cut most electricians take to bring the wire into the panel???

The panel frames and racks should be grounded outside where the panels are located. The panel negative wire should NOT be bonded to that ground.

As far as bonding the battery negative and the solar panel negative to ground, that should be done where the equipment is located. NEC requires that bonding to be done through a GFP device, although many of the brightest minds on this forum feel that is an unsafe requirement and in their own systems have used a hard bond rather than a GFP bond. For liability reasons they might not advise you to violate the NEC on this issue.

As I mentioned previously, you also need to bond the two ground rods to each other.

--vtMaps

mike95490 · July 2012

Re: Inverter to Panel to Outlet??

ywhic wrote: »

Is there any other way to bring the GROUND from the solar panels into the building to the single grounding rod??.....

So, I always wonder who that fella was, that thought it was a good idea to bring the lightning rod ground wire, into the house....

Cariboocoot · July 2012

Re: Inverter to Panel to Outlet??

mike90045 wrote: »

So, I always wonder who that fella was, that thought it was a good idea to bring the lightning rod ground wire, into the house....

Old poem:

There was a man that thought that he
Could win a little bet:
By dousing in some gasoline
A lighted cigarette.
He thought the liquid, being wet,
Would quench the flame somehow.
There was a man who reasoned thus:
He is not with us now.

For relevant content: the matter of connecting the two ground rods brings up the question of the distance between them. The further apart they are, the less necessary it is to connect them. I know that's vague, but it has to do with soil conditions and the likelihood of conductivity between the two points and whether there is the possibility of the ground turning into a battery or capacitor.

Otherwise, the panel frame ground acts more for removing the possible shock/interaction with stray/ambient Voltage whereas the negative of the system grounding is a safety function against short-circuit.

I've now just confused everyone, but hey! Why should I be the only one functioning in a mental fog here?

BB. · July 2012

Re: Inverter to Panel to Outlet??

From what I understand, lightning will only follow a typical "wire" a few tens of feet--More than that, it will dissipate into the ground or "go elsewhere".

Place a ground rod at the edge of the building (near main panel). Ground everything in the building "normally". Then run one 6 awg wire from the main panel earth/neutral bond (if you bond neutral), directly to the earth ground rod (no sharp bends, using NEC approved wiring, clamps, etc.).

If you have a panels "nearby", you can run a ground rod next to the array (to the metal mounts/rails--do not ground the +/- leads).

The normal thing to do is take a 6 awg (minimum) cable from the battery negative bus to the earth ground rod.

Here is some more lightning stuff from an earlier set of posts:

BB. wrote: »

A couple threads about Lightning:

Off Grid Grounding Technique?
Another Question, this time about Lightning

Note, the above are discussions, not a do A, B, and C--and you will be "safe". There probably is no such thing with lightning. Several different techniques are discussed--and a few of those posters even have experience with lightning. :cool:

And our host's consolidated FAQ page:

www.windsun.com
Lightning Protection for PV Systems

From other past posts here, Windsun (admin/owner of NAWS), he said that most of lighting induced failures he saw were in the Inverters' AC output section.

Towards the end of this thread is a very nice discussion of proper generator grounding.

-Bill

Cariboocoot · July 2012

Re: Inverter to Panel to Outlet??

Right. And what you're trying to do by grounding the panel frames/mounts is to give that stray Voltage a short path to ground that is not through the electrical wiring of the array and into the house where it can do some really bad damage. If you are in a lightning-prone area the delta arrestors on the wiring can help with this too (connected to the frame grounding rod).

And always remember we're talking about the high ambient Voltage that occurs in the area around lightning strikes. There is nothing that can protect against a direct hit.

vtmaps · July 2012

Re: Inverter to Panel to Outlet??

Cariboocoot wrote: »

If you are in a lightning-prone area the delta arrestors on the wiring can help with this too (connected to the frame grounding rod).

He can do better than Delta arrestors... check out Midnite's offerings. --vtMaps

Cariboocoot · July 2012

Re: Inverter to Panel to Outlet??

vtmaps wrote: »

He can do better than Delta arrestors... check out Midnite's offerings. --vtMaps

Why do you feel these are better?

vtmaps · July 2012

Re: Inverter to Panel to Outlet??

Cariboocoot wrote: »

Why do you feel these are better?

Because I believe everything I read at Midnite's site

Don't you?
Seriously though, do you see anything misleading or wrong with their claims and specifications? --vtMaps

Vic · July 2012

Re: Inverter to Panel to Outlet??

It appears the the venerable Delta units are a spark-gap surrounded by sand in an ABS or PVC case. Fairly rundimentary "protection".

Found this Video on the Midnite site. It is a bit lengthy, but MN had the Delta and MN SPD protectors tested at a testing lab. That is the heart of this video FWIW:
http://www.midnitesolar.com/video/spd/spd.php

Have used Deltas in the past, and am thankful that no lightning strikes for them to "protect".

Here is the SPD (Lightning Protector) Topic on the Midnite site:
http://midnitesolar.com/smf_forum/index.php?board=13.0

Vic

mike95490 · July 2012

Re: Inverter to Panel to Outlet??

Delta & Midnight SPD are 2 very different systems.
I think both players have tilted the scales, and I'm actually, installing both.

Deltas are a simple arc gap in a quench media (fancy sand) They can shunt a terrific amount of power through themselves, till the external wires melt, or the arc plasma ruptures the container. They don't activate till about 9,000 volts

The Midnight SPD is a solid state suppressor, it is manufactured in several cut-in voltages, and is likely to suppress a strike or near strike, that the Deltas won't even blink at. There is a lot of 400V - 5,000v noise and pickup happening in a grid, and the SPD's will do a pretty good job at containing them, till the big one hits, and the Delta takes over.

Neither brand lists enough info to determine how many joules of power they can survive. Any real large energy surge will fry both types, and hopefully, their sacrifice, will spare your gear.

Cariboocoot · July 2012

Re: Inverter to Panel to Outlet??

The Deltas are not spark-gap, they're SOV's. And they're half the price of the Midnight units. For economical lightning only protection they're an excellent choice.

If you have any type of grid-interactive system go for the Midnight units at least for the line connection as they will handle a wider range of Voltage surge which could damage the equipment.

Again it's a matter of evaluating what the needs of the particular system are. If you don't live in a lightning-prone area you don't need arrestors.

My system (lots of lightning about lately) uses several million natural attraction rods known as "trees". Effective, but the install takes 150 years!

ywhic · July 2012

Re: Inverter to Panel to Outlet??

My panels will at the most be 18 feet from the back wall of the cabin.. 2 at 18 ft, 2 at 14 ft, 2 at 8 ft.

The install of the GUTS will be on the back wall as well.

Could I use 1 rod for all this.. somewhere in between the panels and the back wall items..

BB. · July 2012

Re: Inverter to Panel to Outlet??

Put the main ground rod at the wall of the cabin (near main power panel/battery bank).

If you have a chance of lightning strikes--I would drive another ground rod (or bury a ground plate) next to the array and bond to the frames. If you want to bury a 6 awg (uninsulated) or heavier wire to tie the two ground rods together--your choice, should not hurt anything (as I understand).

-Bill

ywhic · July 2012

Re: Inverter to Panel to Outlet??

Ok.. thank you..

Now

The controller, inverter, battery bank, all get grounded together.. as well as the GROUND from the AC panel/outlets on that 1 rod correct??

I would like to not have neutral bond going on in the system as I may need to in a pinch use a neutral/ground bonded inverter.. which as we've learned as of late 2 in the same system causes the inverter with GFCI to kick-out..

Again I will be using GFCI outlets near water and such items..

BB. · July 2012

Re: Inverter to Panel to Outlet??

Sounds good... If you have "bad soil" conditions (poor electrical conductivity)--Driving several rods near the main rod and running short wires from those rods back to the main rod is the usual solution.

Neutral bonding--Floating neutrals are not the worst thing in the world. But, as you know, if you use GFI outlets, they may not operate reliably (false tripping).

-Bill

ywhic · July 2012

Re: Inverter to Panel to Outlet??

Ala.. underground Tesla with multiple rods..

vtmaps · July 2012

Re: Inverter to Panel to Outlet??

In your OP on this thread you indicated that you would remove the bond in the inverter, hard wire the inverter to your panel, and bond the system in your panel.

Now you write:

ywhic wrote: »

I would like to not have neutral bond going on in the system as I may need to in a pinch use a neutral/ground bonded inverter.. which as we've learned as of late 2 in the same system causes the inverter with GFCI to kick-out..
Again I will be using GFCI outlets near water and such items..

good luck figuring out what you want to do. --vtMaps

ywhic · July 2012

Re: Inverter to Panel to Outlet??

vtmaps wrote: »

In your OP on this thread you indicated that you would remove the bond in the inverter, hard wire the inverter to your panel, and bond the system in your panel.

Now you write:

good luck figuring out what you want to do. --vtMaps

From the OP..

I was planning on keeping the neutral/ground un-bonded in this scenerio..

So 3 separate wires going to all points.. panel will have load (breaker), a neutral bar, and a ground bar..

(My cabin panel has a simple single ground/neutral screw that can be put in that would tie them together based on what you folks say)

^^^

& Apparantly from what I gather (from reading BB's post) bonded or un-bonded doesn't matter..

What is the bad side of not bonding the neutral to the ground on the AC side?? (or what is the point??)

Cariboocoot · July 2012

Re: Inverter to Panel to Outlet??

The point of bonding "neutral" to ground is that if it is not done you don't have "neutral": you have floating 120 VAC and the white wire can give you a shock just like the black wire. You can turn off the breaker on the "hot" side and the "neutral" side will still show Voltage potential to ground. To make the wiring totally safe in this instance you need to treat it like 240 VAC and shut off both sides. This floating AC is typical of portable generators where an actual Earth ground is not practical (although they do usually include connectors for attaching one).

If you've got a good inverter and a ground rod, make the bond. It's safer that way.

BB. · July 2012

Re: Inverter to Panel to Outlet??

You cannot AC neutral bond most MSW inverters. Most TSW inverters can have the AC neutral bonded (and some do it internally). As always, read the manuals.

In a way, MSW inverters are referenced to Battery Ground (which is usually bonded to local chassis/earth ground)... So MSW inverters are not a "floating" outputs.

As to whether to bond or not a TSW inverter--I cannot force anyone to do one thing or the other.

Engineering is a series of trade-offs (fast, good, or cheap -- pick any two -- is an old engineering saying).

Simply adding a neutral bond--Can reduce costs (single pole breakers, none required for neutral wiring side). Can increase or decrease safety (for small AC systems, floating AC outputs cannot cause a shock.

For larger systems, enough leakage current that it is not possible to "really float" an AC system (capacitive coupling of wires, electrical filters, etc.).

Floating (no neutral bonding) can reduce the effect of lightning--direct energy away from loads)--Neutral bonding converts Common Mode voltage (all lines black/white/read are at 2,000 volts--which is OK for hardware--every piece of 120/240 VAC electrical equipment is "hi-pot" tested prior to shipment) to Differential Mode Voltage (black is at 2,000 volts from lightning, white is at ground--Will blow most AC connected sources/loads--I.e., now lightning looks like feeding 2,000 volts to a 120/240 VAC circuit/load).

For most people, bonded/floating neutrals for AC power of (smaller) PV systems is not going to make a huge difference. Any choice will have its own positives and negatives. If the inverter output is over 1,800 watts (~15 amp service and 14 awg wiring), I would seriously consider neutral bonding and/or double pole breakers even for 120 VAC inverters. The issue of too much current through neutrals (and no breaker/fuse) is probably what will "address" the most common failures (short circuits).

Sorry, no simple answer here.

-Bill

ywhic · July 2012

Re: Inverter to Panel to Outlet??

It would appear the inverter in question has a hardwire output and a GFCI outlet.. (we know how that works with neutral/ground bonding..LoL)..

Since we clarified everything..

I will use the hardwire terminals.. as it is not neutral ground bonded from what I've read in the manual and I just talked to Samlex tech support and they confired hardwire terminals are not internally neutral/ground bonded and I should do it at the panel..

I will neutral/ground bond at the AC panel (with the little screw).. I don't want floating AC..

Worst case in a pinch I can remove little screw and then patch in a GFCI type inverter which has it internally..

Cariboocoot · July 2012

Re: Inverter to Panel to Outlet??

Just to throw another wrench in the works ...

Breakers on the output of an off-grid inverter usually never trip. The inverter itself is far more sensitive to over-current and will fault before any circuit protection is triggered.

From my own experience using a grounding rod and bonding the neutral presents the fewest potential hazards in most off-grid non-mobile applications (given an inverter that allows this).

BB. · July 2012

Re: Inverter to Panel to Outlet??

And for "home/cabin" wiring--I too would bypass the GFI on the inverter--And just install GFI's at point of use (sinks, outside, wet areas).

Having a GFI on the main output of a "home/cabin" inverter--If there is a GFI fault anywhere, you lose 100% of your power--Which if you use 120 VAC lighting, will throw you into total darkness--Not "safe" either.

-Bill

Vic · July 2012

Re: Inverter to Panel to Outlet??

In the past I've used Deltas. From the tests that MN comissioned at that test lab, seems to me that the Delta units are a spark gap. It is conceivable that the sand kinna quenches the arc, but if the arc is sustained guess the Delta melts down, unless there is some fuse mechanism. Mabe it melts clear and stops the arc. I see no reason to continue to use the Delta units in my applications.

Mike, RE the amount of Energy "Asorbtion" on the MidNite SPD, on page 2 of the manual linked below, there IS a spec table that specs that value for each of the SPDs:
http://www.midnitesolar.com/pdfs/SPD_Installation_Manual.pdf

And, below that table is is a graph of Peak Voltage vs Peak Current for MN's three SPDs

On the MN Fourm, just looked at a video that was linked in Jan this year ... kinna interesting:
http://www.youtube.com/watch?v=_ciAkYZzfDo&feature=youtu.be

While I have no financial interest in MidNite, I definitely am a true believer. They are very aggressive at providing products that seem to solve problems for both GT and OffGrid users, and, to me, they seem to be continually extending and improving their Solar products. What more could almost anyone ask for?
Partisan Vic

Inverter to Panel to Outlet??

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