Help me find a Hybrid Inverter with these specs...

[APD]

Hi,
New to the forum, I joined because Im having trouble finding the inverter I want.

I want to do a residential hybrid system with these requirements:

3-4 KW (3 kw of PV panels)
240 AC output
24-30 volt DC battery input (for lithium 28v)
User programmable control of charging set points (because of lithium)
UL 1741 listed for grid intertie

There are Taiwan and China models (MPP solar, Ginlong, etc) that I would absolutely go for but they are not UL listed, so my power company wont allow grid tie. These range from about $500-1200. Lots of people using them in other countries with good reviews.

SMA sunny island is a candidate but its over $3000
Outback makes 120v models, so I would need two, again over $3000

That kinda kills the project if I have to spend over $3k just on the inverter.

Im also exploring the possibilty that I may have to do it with two inverters, one off grid and one grid tied. I would rather not if possible. I want to keep it as simple as possible. Many grid tie only inverters want high DC input voltage, and off grid inverters seem to want lower DC volts.

I cant be the only one who has done this, why are there so few inverters with these specs?
Any recommendations?

BTW, the main reason for 240v requirement is I want my well pump available during grid outage. All other critical loads are 120v.

[ButchDeal]

Outback radian

[APD]

Thanks, but they're $3k and 48 volt DC

[ButchDeal]

Actually you could get a single outback plus their auto transformer for the well pump. This is exactly how mine is configured

[Mike90250]

You are not going to find a utility intertie inverter that is not 48V or a HV-DC string inverter

http://solar.schneider-electric.com/product/conext-xw-na-solar-inverter/

To get multi-killowatt rating (to backfeed the grid for >1hr) you have to have higher battery voltage to prevent copper loss from eating up your savings

[APD]

Yes! I was wondering if anyone used a transformer for this situation. That might be the way to go. I will look into that.

[APD]

You are not going to find a utility intertie inverter that is not 48V or a HV-DC string inverter

Yes this is what Im discovering.

[Mike90250]

Yes! I was wondering if anyone used a transformer for this situation. That might be the way to go. I will look into that.

Problem with a transformer, you have to have one large enough to pass the motor starting surge. The inverter might be able to supply 180% rated power for 5 sec, but the transformer has to be large enough to pass that surge too. A 1Kw rated transformer falls apart at 1.1kw when the core saturates and can't transfer any more energy. You might get 1 or 2 overload cycles out of it, but the motor needs about 3 seconds to come up to speed. (120-300 cycles) The transformer won't be hurt much, but it just cannot pass more power than rated for .,

[ButchDeal]

The outback auto transformer is designed specifically for well installations and works well in such configurations.

[Mike90250]

The outback auto transformer is designed specifically for well installations and works well in such configurations.

Looks like there is 1 transformer, with 2 different ratings & part #'s:
PSX-240 6kVA rated with enclosure and cooling fan. (Includes two pole 25 amp AC breaker)
or
Autotransformer without enclosure 4000W, 120V/240V, 60 Hz, FW-X240

The cooling fan adds 2kw to the rating

[ButchDeal]

Looks like there is 1 transformer, with 2 different ratings & part #'s:
PSX-240 6kVA rated with enclosure and cooling fan. (Includes two pole 25 amp AC breaker)
or
Autotransformer without enclosure 4000W, 120V/240V, 60 Hz, FW-X240

The cooling fan adds 2kw to the rating

It has more than a cooling fan. The PSX-240 has an enclosure, with fan, and fuses. The manual gives it a few different wiring options but one of them is just for a well pump, and they suggest wiring it up after the pressure switch. Mine is set up this way.

The FW-X240 is generally used to balance between the inverters providing 240V in an off grid situation, allowing the system to shut down one inverter on light loads. It doesn't need an inclosure or fan as it is generally installed in the Flexpower enclosures and has a lighter load as the other inverter is cranked up as needed.

[jflorey2]

Hi,
New to the forum, I joined because Im having trouble finding the inverter I want.

I want to do a residential hybrid system with these requirements:

3-4 KW (3 kw of PV panels)
240 AC output
24-30 volt DC battery input (for lithium 28v)
User programmable control of charging set points (because of lithium)
UL 1741 listed for grid intertie

I will second the Outback suggestion. GVFX3524 plus a transformer.

[ButchDeal]

I will second the Outback suggestion. GVFX3524 plus a transformer.

I would recommend you switch up to the 48V version and use the newer version of the inverters VFXR which replace all the FX versions.
You should be able to put the batteries in series to get ~48V range instead of 24V.
Means you can use one CC as well.

I personally used the preconfigured versions from Outback which have a lot of the wiring, monitor, CC, etc all set up - FLEXpower One FXR would do it. Though a bit more costly it is cheaper than all the components and saves a lot on the install time.

http://outbackpower.com/index.php/outback-products/make-the-power/item/flexpower-one-fxr-series?category_id=522

[APD]

I was told that the Outback GTFX & GVFX line of inverters need to have batteries connected to even function, so it would not act as a grid tie inverter without batteries.
Can anyone confirm this?

[ButchDeal]

I was told that the Outback GTFX & GVFX line of inverters need to have batteries connected to even function, so it would not act as a grid tie inverter without batteries.
Can anyone confirm this?

I don't know who told you this but they are partially right and mostly wrong.

They do require batteries but they are bimodal (Hybrid) inverters which is exactly what you asked about. They will function on grid. In fact that is exactly what the G stands for. But they have been replaced by the more capable and software reprogrammable (Thus the R) FXR and VFXR series which ALSO can work on grid.

I have one and it is on grid and we have installed several others both on and off grid.