I noticed that the Outback catalog and spec sheets do not have any references to the FX 2000 actually being UL 1741 listed at all, although it is ... designed for both residential and commercial stand-alone and utility-interactive applications ... .

The Outback Press Release for the FX 2000 says that it is listed under UL 1741, “Inverters for Use in Independent Power Systemsâ€￾ by ETL. The press release is dated Sept 25, 2002.

It seems that without UL approval for Grid Tie use, it would be difficult to get a building inspector to sign off on installation of this unit if it were grid tied.

Will these units (or do they now) have a listing that specifically includes Grid Tie usage? If not now, when is it expected?

Thanks! [img]images/smiles/icon_biggrin.gif[/img]

We currently are not listed for utility interactive operation - nor is the ability enabled in the current software. We will not offer the ability to sell power back until we have the necessary approval (except in our test installations).

We expect to have the complete utility interactive listing after the first of the year - but it is not done until it is done.

We do have aproval to operate in two modes with the utility grid at this time. The first mode is basically a UPS mode. The second is what we call "HBX" mode in which we transfer the AC load from the utility grid to the inverter when the battery is charged and open a 60 amp AC input contactor built into the FX inverter. When the battery gets low we reconnect the AC loads to the utility grid and allow the PV/wind/hydro to recharge the battery.

There will be several other modes in the future version of the FX inverter for utility interactive applications. We also will upgrade any previous versions of the FX inverter for a $100 charge (includes shipping cost and the required UL islanding tests) so the customer won't be stuck with an older, obsolete version.

I'd like to encourage OutBack to provide a means to operate a batteryless grid-tie system during a grid failure. Vanner sells such a system, but is priced out of sight and doesn't seem a viable option. In California (and maybe coming soon to a grid near you) we have had hot weather outages due to grid capacity problems. These occur on hot afternoons when there is plenty of sun available to operate a PV array. I don't want to deal with the safety/maintenance issues of batteries, but would like to have a backup circuit that can use whatever power is available directly from the PV array.

Rob,

First let me state that I am still pretty new to all of this, so bear with me if I make some incorrect assumptions.

While I agree that having a grid tie system capable of producing 'backup' power during an outage (I live in CA too) would be nice, I can see where it would probably not be feasible from a liability point for a company to offer it. It's my understanding that in order to be grid tie certified, the inverter must be able to stop producing power when the grid goes down. Of course this is a safety issue as to not feed power back into the grid. However, you are basically asking for a way to defeat that safety feature. How can a grid tie inverter be designed to ensure that it does not feed power back into the grid during an outage? I would think the only way to prevent it is to turn off the main breaker. So unless the inverter had a way to do that automatically ($$) I don't see this as possible on any reasonably priced inverter. If it was left to the operator to manually turn off the main breaker and flip some sort of 'over ride' switch on the inverter, I think that would be asking for trouble and I doubt it could get certified.

[ November 14, 2002: Message edited by: Mark Lopez ]

Mark and all,

GridTie inverters are designed to transfer all the available solar power and dump it into the grid. I use the term dump , since the inverter is designed that the grid can take ALL of the power it can generate.

This is very different than a UPS/Standalone mode , where and inverter is regulating the voltage and supplying current only as needed by the load.

To do this in a "battery less" mode , the inverter would need some way to "know" what the available DC power from the array is ... this is backwards from the grid-tie units that load the array (using the grid as the load) to track to maximum power point.

I could see if you program the inverter with a fixed DC array voltage set point , it could provide some percentage of power to the AC side but without batteries ... and surge load would be difficult at best to not collapse the array voltage.

SMA is working on a box , the now defunct AE multimode did this but they all require some storage in excess of the array to effectively regulate the power delivered.

Anyways , this is not a vendor specific issue and I am attempting to educate others why grid-tie inverters can't just simply supply some power if the grid was down and isolated , this is beyond the fact they are current , not voltage based regulated designs.

I do have as a home project , to make special code for my XR’s to sync to the generator when the grid is down … the idea being to help the surge and supply enough extra power so I can run the AC when the grid is down and it is sunny !!! , this is totally different algorithm and if it works I’ll report back on how well it does ….

Henry
[img]images/smiles/icon_biggrin.gif[/img] [img]images/smiles/icon_biggrin.gif[/img] [img]images/smiles/icon_biggrin.gif[/img]

[ November 14, 2002: Message edited by: Solar Guppy ]

We have already publically demostrated to ability of the FX2000 inverter to operate without batteries to provide utility back-up in addition to the utility interactive "sell" mode.

We even in fact where able to start a large 2+HP 120 vac air compressor with the FX2000 with help from a bank of super capacitors we connected up for the demonstration. The super capacitors solve many of the battery issues but are expensive at the present time.

This ability will be acceptable to UL/NEC/utilities because the FX2000 includes a built in 60 amp AC transfer switch to isolate the AC loads from the utility grid when providing the back up capability. This is the same way that a UPS operates loads when an outage occurs - just with PV instead of batteries.

Chris,

Stored energy , whether super caps (which are 10x the costs of lead-acid batteries) or batteries are required to be a stand-alone mode.


My point is the array has no storage .. it's use it or lose it and if your load is greater than the array ..poof goes the lights.

Here in florida it would have NO USE ... maybe in the desert or other clear climate it might be good but what your saying you have demonstrated is nothing more than a gimmic IMHO ...


[img]images/smiles/icon_biggrin.gif[/img] [img]images/smiles/icon_biggrin.gif[/img]

<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by Solar Guppy:
what your saying you have demonstrated is nothing more than a gimmic IMHO ...<HR></BLOCKQUOTE>

I would hardly call what we demonstrated a gimmick ... and in Florida it could be extremely useful when the power is off for days from a huricane and you sit there with 3 kW of PV on your roof doing nothing and you can't even run a radio off your system because the utility is not available.

Sure super capacitors are expensive - but so is PV. The idea is that for some people, batteries are not an option, but they still want a limited back-up power from their PV system. It is a reasonable option for SOME customers - one size does not fit all... The amount of capacitance can actually be fairly small and is easily increased.

Having a limited amount of electricity IS very different from having no electricity at all (try it some time). More and more communities are restricting back-up generator installations also - so PV + inverter may be the only solution...

[ November 14, 2002: Message edited by: Christopher Freitas ]

Hi Chris,

My reference to the gimmick was the comment on starting a 2HP motor.

Questions:

What was the STC rating of the array you hooked the 2HP motor up to ??

Was the motor under load or free wheeling

How many Joules are your storing in the cap bank ?

Could you post a link to the caps you used … I would be interested in seeing if they have changed to have low esr and allow high discharge rates.


Henry
[img]images/smiles/icon_biggrin.gif[/img] [img]images/smiles/icon_biggrin.gif[/img]

Chris - Right On! The issue is about using an available resource instead of ignoring it because it isn't perfect. I accept that PV doesn't produce at night, and is marginal during clouds, but these are not reasons to totally ignore several kilowatts during a grid outage.

Even if the PV power is intermittent, it would still be useful to recharge a cell phone battery or a car battery that has been run down by using the radio too much. If the power is more stable, then maybe it could operate a TV and/or a fan. I've noticed that my 2880 watt array produces several hundred watts of power even during overcast conditions. As an emergency resource, 200 watts is immensely more than zero.

Maybe you could program Mate to display power availability and usage. If clouds have limited PV production in the last 15 minutes, then it would be useful to know how much power was available under the cloud even though there is full sun at the moment. If you want to get really fancy, Mate could know how much power was available under similar conditions in the past. Maybe it could predict the time of day when current usage would exceed the available PV output.

Since an FX-2000 inverter plus an MX-60 controller price out at about the same as a ST2500 or SB-2500, the added function should set a new standard. Since the price is about the same, it's a no-brainer to go with the added function.