Grid Tie Inverter with no sell back

[veggiepower]

Can I use a grid tie inverter like the OutBack GVFX3648 and use it just to power my house, or will these grid inverters push power back to the grid if you can't use it all? This would be connected to a 48 volt battery bank and wind generator supplying the battery bank.

I would like to power the house with this and stay on the grid at the same time.

[TomW]

veggie;

I have an FX series and it will either pass through grid power, charge or run off batteries. You can set it all up with the Mate.

I call it "grid connected" as opposed to "grid interactive".

The term grid tied is confusing because many inverter are tied to the grid but do not feed the grid.

Just the view from here.

TomW

[dlenox]

veggie,

I have an Xantrex XW and it is configurable as to if/when I sell back to the grid.  I would have to think that others also have this feature.

Dan Lenox

[veggiepower]

I would like to tie the grid inverter into my house breaker box and let it add power to what the house needs. Can I do this without getting the power company involved? I believe the extra power would go back into the grid.

Thanks!

[ghurd]

Yes, the extra goes back into the grid.

No, the power company needs to be involved.

They have some concerns with linemen being killed, fires, burned up equipment, and other things.

Some people have very good luck with the power company being very helpful.

That is the place to start in real life.

DamonHD's diaries are the place to look until then.

He is UK, but it's the same idea.

G-

[richhagen]

I have a Trace (now Xantrex) 4048 inverter, and I wouldn't have known this before reading the manual.  It has a mode called 'Low Battery Transfer', or LBX mode which connects your loads to the inverter from the battery bank when the batteries are sufficiently charged, and then to the grid when the batteries are depleted.  To quote from the Trace manual:

"Low battery transfer mode is an alternative way of operating "off the grid" using the utility for backup power instead of a generator.  The system essentially operates as a stand alone power system, independent of the utility grid.  When the system is no longer able to keep up with the power requirements of the AC load, discharging the batteries to the LOW BATTERY TRANSFER VDC setting, the inverter connects to the utility grid.  It then feeds utility power directly to the load and recharges the batteries.  When the battery voltage reaches the LOW BATTERY CUT IN VDC setting the inverter disconnects from the utility grid and once again operates the AC load from the batteries.  Since power is never sold back to the utility, this configuration does not require utility approval."

One little annoyance with this mode when your intent is to charge your batteries from solar or wind is that the battery charger kicks on when the batteries are low, and the programming only allows you to turn the amps down to two amps, and adjust the charge voltages down, not turn the charger off in this mode.  I believe that the grid tie outback inverters have a similar mode.  Hope this helps, Rich

[TomW]

Rich;

That LBX mode is the bit I [ineffectively] tried to illustrate. It is actually a function of the "Mate" in an Outback system.

At least I think it is.

Some very versatile options on the higher end inverters actually.

TomW

[richhagen]

I was just looking through the manual to the Outback FX2012ET which just went to Fiji for an expedition there next month.  Preliminarily, it appears that if you have the Mate interface, you could program a similar mode, although I would need to study it a bit more to be for certain.  That particular inverter was not the Grid Tie version, which is denoted with a 'G' in the front of the model number.  Rich

[richhagen]

I must have been typing the next bit while you were typing.  Hope your day is going well Tom :-)  Rich

[TomW]

Rich;

Yes, mine is an FX2524 and it is very versatile with the Mate, otherwise it seems you can just set the low voltage disconnect but may be wrong. I used mine for a good year before I added the Mate. Its gone from "dumb" to "very smart" and has a PC interface built in. The Mate allows you to stack them for either 2X the power or 2X the voltage for pumps or other high voltage needs. Actually I think the Mate can control 8 inverters for about any output specs you need.

TomW

[richhagen]

I thought about getting a mate for the inverter for the school in Fiji, but I was a bit worried about the RJ45 type connectors surviving very long in the marine environment, that and the fact that there would be no one there trained to operate it, therefore someone might change the settings on the 'new toy' to a state where it would not function as needed.  Also, there is no need for it to interact with a grid there since there is no grid.  I figured that simple was better, and figured the money would be better spent on other resources for now.  I just hope the inverter all gets there as I broke it down for shipping hoping that the pieces would go out with the mail on the small plane to the island.  Rich

[TomW]

Rich;

As far as the rj45 connections, a gob of conductive grease over the whole connector should seal it good unless it is disconnected often which it probably shouldn't need.

Mine had a little tube of the stuff in the cable bag I think.

Pretty sure it would eliminate uglies in the connection.

TomW

[Ungrounded Lightning Rod]

I'd be more concerned about the circuit boards surviving than the RJs.  RJs are built to telecom standards.

[electronbaby]

i have a pair of GVFX's running my off grid place. http://www.windsine.org/gallery/main.php?g2_view=core.ShowItem&g2_itemId=282

You can set them up either way. The GVFX can grid tie and the FX can use "grid support" to charge the batteries with grid power, but will not grid tie.  They usually sell for the same price, so make sure you know what you want to do in the future.

You can use the GVFX to do what you want to do, you just have to disable "sell" in the menus of the mate. When you do this, it will still pass power, and be UL1741 compliant with a transfer switch and NOT SELL to the grid. You can still retain the ability to charge from the grid if you wish. They still sync up and you can set the charging current limits too. They are very versatile, however you must understand how to navigate all the menus (it can be rather confusing if you are not used to their menu structure).

[TomW]

Roy;

You have mail.

TomW

[richhagen]

I did opt for the sealed variant of the inverter for that reason.  Once reassembled it should be reasonably well sealed up and protected from the marine environment inside with o-rings and gaskets where the case comes together, and where the battery lugs and the board side with the outputs penetrate.  The circuits are mounted inside a sealed case with the transformer.  A fan, also inside this sealed case circulates air over them and the inside case surfaces to disperse heat.  It is rather elegantly simple in design with three circuit boards, might be partly boB's doing.  This was the 'turbo' variant which also has a small fan under the top case.  I suspect that that external fan won't last very long, but it is not essential for the low power operation that this unit will likely see for most of its life.  The RJ45's connect on the wiring attachment part which is not sealed of course, although it is somewhat protected inside its compartment.  It would be the end connected to the Mate that I would be most concerned about.  I did see in the manual that it recommends using grease as TomW suggested, and apparently is supplied, to protect the jack and plug in harsh environments, which this inverter will likely see. Rich