Does anyone have a source for dealing with Inverter hook up to a manual transfer switch?

Tes42

Hi guys, new member here and I been reading furiously the last few days some old posts and I was wondering if I am missing the solution to my questions. Basically, I don't know what inverter to by for my situation, and confusion around how to rewire the connected neutral and ground wire bond that is in my homes breaker panel. Or optionally I would rather just by an inverter that does not have a bonded neutral.

Background details:
Right now my system is bare bones a couple 100 watt 18V panels wired in series (my plan is to add in pairs as I expand), and two AGM 12V 100AH batteries, and a third in the near future wired in parallel to maintain a 12V system. Intended to only power some of the 15 Amp branch circuits of my house (no microwave, no refridge, no washer ect.). And for days when I may not have enough sun I installed a manual transfer switch:

Reliance Controls Corporation 31406B Pro/Tran 6-Circuit Indoor Transfer Switch for Generators Up to 7,500 Running Watts

 To cover some of these loads (small ranch home) I don't think I need too much more than 600 watts but I may be interested in getting up to a 1500watt sine wave inverter (if needed in the future), can anyone recommend some details as to an inverter that can work in my situation? Also if I have to unbond the neutral wire in my breaker box is there a schematic showing how to do this?

Thanks.

Estragon

To clarify - is this a totally off-grid (not a backup) system?

What kind of generator?

Tes42

This is totally off-grid, and no generator. I do get all my power now from my electric company and I will still be using that power for most of my house, except for a few branch circuits that I hope to power through the manual transfer switch.

MrM1

You are on the exact right track with the Reliance Controls gear,  but wondering why you are considering the 31406 B?

Have you considered the 306C as it has circuit breakers for the incoming solar loads and 3 position toggle switches for transfer.  I use the 10 circuit 50 amp version.  Works flawlessly.  Look at the manual, as it describes how to handle the load, neutral and ground.   But you will need to get an inverter that is 240v Single Split Phase or you will have to do some rewiring inside the Pro Trans as they are rated for 240v Single Split Phase and NOT for just 120v. 

But IMHO,  you are starting kinda backwards.  The first thing you need to do is some actual load calculations to determine the actual loads you want to run.   You say you need 600 watts.  Is that per hour?  Per day?    200 Ah's of battery is good for 1 200 Watt hours at 50% DOD best case. How many Watt Hours (not Watts) will you be needing for a 24hr period.  This will determine battery bank size, number of panels, and inverter size.  I would say for safety sake you don't need more than a 1000W inverter on a 12v battery.  Here is why ...

1000W / 12v = 83 amps
1500 W / 12v = 125 amps

At 1000W you will need #3 gauge battery cable for all series / parallel connections and connection to the inverter.  1500W will take 1/0 all the way thru.

Also not sure if you care,  but if you are wiring this inverter into the house for a few branch circuits thru the main panel,  it needs to comply with UL 1741 standards or if you burn the house down,  insurance will not pay. 

Tes42

The biggest concern I do have is your last point. The transfer switch does not seem to mention using an inverter only a generator so there is my concern, and then when I read things about how inverter split voltage on both the line and neutral and these can't be used, or if they can they need a feature internal adjustment I think, and this is where I need most help.  

I agree that all I need is < 1000W inverter in my case. I did do the calculations for three rooms of my house running lights only and since I run all energy saving florescent spiral type bulbs my calculated amps were low. I did not figure in battery bank size since I figured I can flip back to line voltage when needed and expand that in the future. I had the following notes:

Kitchen Lights 40W x 6 hours = 240W
Dining RM Lights 30W x 6 hours = 180W
Living RM Lights 40W x 6 hours = 240W

Total: 660W x 1.5 (loss factor) = 990W hours

990W x 2 (50% discharge) = 1980W / 12V = 165Ah (one days worth of storage)

I did buy 2 AWG to parallel the two batteries, and I will double check these figures on the 2 AWG.

As far as my Transfer switch it seems to be similar to the one you mentioned here is a image of it:

Photowhit

I'll just speak to the inverters without neutral ground bonds. Most inverters that are UL 458 (mobile use) will have an internal bond. There are a few pure sine wave inverters that will have a detachable bond, like the Exeltechs, down to the 600 watt XL line are hard wireable and have a detachable neutral ground bond. It appears they company still has a $100 rebuild if rebuild able policy, making used units attractive. I use the 1100 watt unit and it's quite nice in that range. It does use about 16-18 watts per hour in the 24 volt version.

It's not unusual to find them in the $2-300 range on eBay, nothing currently... A couple have sold in the $150 range this year.

In addition all UL 1741 inverters, for household use will either not be bonded or be detachable.

Estragon

> @Tes42 said:
> This is totally off-grid, and no generator. I do get all my power now from my electric company and I will still be using that power for most of my house, except for a few branch circuits that I hope to power through the manual transfer switch.

To be clear, this is not totally off-grid. You have grid power, and if I understand the transfer switch operation, it will backfeed generator (or inverter) power to the grid. Aside from fire risk, a lineman trying to restore power in an outage is unlikely to thank you for making a wire unexpectedly live.

What you want is a fairly simple lockout panel that lets you run a few circuits from either grid, or a generator/inverter, wired such that loads are connected to one or the other, but never both. If you want circuits to run off inverter only, you don't even need a switch, just a panel serving those loads from the inverter.

MrM1

Estragon said:

To be clear, this is not totally off-grid. You have grid power, and if I understand the transfer switch operation, it will backfeed generator (or inverter) power to the grid. Aside from fire risk, a lineman trying to restore power in an outage is unlikely to thank you for making a wire unexpectedly live.

not exactly. the transfer switch Tes42 is referencing has a 3 position toggle switch which isolates the circuits you connect to it so you can toggle between Grid / Off / Gen.  When in the Gen position,  the connected circuit is in no way connected to the grid (except that the circuit is still connected to the ground and neutral of the main panel bus bar same as it would be if using a generator similar to if you were using a simple lockout panel).    In his case he is substituting an Inverter for the Generator.   So there is no back feeding.  These Reliance Control switches are UL rated for this very purpose.  They are designed for use as optional standby switches for the purpose of providing on-site generated power to user selected loads / branch circuits and suitable for use in accordance with Article 702 of the National Electrical Code.   The OP is not using a generator,  but is instead using an inverter as the power source for this switch.

@Tes42 Not sure why you would want the one with push button trips rather than the 15 amp hardware store replaceable breaker model. 

Tes42

Well yeah I agree the push button setup I got looks odd now that you say that but I was trying to save a few $$. Functionally though I think its very similar if not almost the same.

Tes42

Photowhit said:

I'll just speak to the inverters without neutral ground bonds. Most inverters that are UL 458 (mobile use) will have an internal bond. There are a few pure sine wave inverters that will have a detachable bond, like the Exeltechs, down to the 600 watt XL line are hard wireable and have a detachable neutral ground bond. It appears they company still has a $100 rebuild if rebuild able policy, making used units attractive. I use the 1100 watt unit and it's quite nice in that range. It does use about 16-18 watts per hour in the 24 volt version.

It's not unusual to find them in the $2-300 range on eBay, nothing currently... A couple have sold in the $150 range this year.

In addition all UL 1741 inverters, for household use will either not be bonded or be detachable.

Thanks for the tip, I will search for UL 1741 inverter types.

Tes42

Estragon said:

> @Tes42 said:
> This is totally off-grid, and no generator. I do get all my power now from my electric company and I will still be using that power for most of my house, except for a few branch circuits that I hope to power through the manual transfer switch.

To be clear, this is not totally off-grid. You have grid power, and if I understand the transfer switch operation, it will backfeed generator (or inverter) power to the grid. Aside from fire risk, a lineman trying to restore power in an outage is unlikely to thank you for making a wire unexpectedly live.

What you want is a fairly simple lockout panel that lets you run a few circuits from either grid, or a generator/inverter, wired such that loads are connected to one or the other, but never both. If you want circuits to run off inverter only, you don't even need a switch, just a panel serving those loads from the inverter.

Yeah I was wondering if saying it was a totally off grid system would cause some confusion, but I did not want anyone to think this was a grid tied commercial system. But when I through the transfer switch to GEN mode on anyone of the 6 DPDT switches I am then running those on a solar battery bank and then I am no longer on grid.

Someone MUST have a tutorial on this? But then again maybe not too many people do it this way. 
 

Estragon

Although off-grid, I have a similar setup controlling which of two separate inverter systems is used for a number of circuits. It allows me to turn off my big inverters overnight and run lights etc on a small inverter which has much lower standby losses.

If the switch you have is UL rated for this use, it must be ok. On mine, there is a breaker for each inverter AC source, and a metal lockout making it impossible to have both breakers closed at the same time.

MrM1

Tes42 said:

Well yeah I agree the push button setup I got looks odd now that you say that but I was trying to save a few $$. Functionally though I think its very similar if not almost the same.

Here you go

https://www.ebay.com/itm/NEW-RELIANCE-CONTROLS-306A-PRO-TRAN-2-6-CIRCUIT-POWER-TRANSFER-SWITCH-KIT-30-AMP/401508248264?epid=2255911471&hash=item5d7bc1aac8:g:v4gAAOSw~OVWv1en

Not much more than what you are wanting to pay I dont think.  I would just rather have the breaker model because it would be more easily user serviceable. 

As to an inverter,  what is your budget? 

Tes42

$500-$1200 or less but it almost seems like I need a more expensive one with a feature that allows un-bonding of the neutral in the inverter I am guessing but this is the part I am confused about.

I just sent out three emails to three separate inverter companies about this, see what they say IF they even respond.
 

MrM1

If your up for spending $1,200 +/- ... I can't remember what battery voltage you needed,  but you might as well consider the Schneider Conext SW series.  All the models are Split Phase 120/240v.    The only caveat to your budget might be that you would really also need the System Control Panel ... but shop around and price match ... I got my SW 4024 with SCP for just over $1450 (or something like that I cant recall now) 6 months ago.   Heck if you were in FL and need batteries too I'd make you a good deal on my SW with batteries ... I want to sell it and upgrade to a 48v system