Multi Kw 48v to 240v grid tie inverter?

oil pan 4 · June 2018

I'm getting things in order to start doing my sprawling diy solar. The power coop I have is outstanding when it comes to home solar.
I have the panel, breakers, wire all bought I'm going to start putting in the expanded 240v power system to reach out towards where the ground mount panels will be as soon as I'm not working 50 to 60 hour weeks.
I don't want to do a typical grid tie where I run the DC voltage at 100 to 500 volts. I know it saves on copper costs, but I have nearly unlimited 8, 6 and 4 gauge cable. Plus I want to lay all the ground work for 48v gird tie so one day if I decide I want to go off grid all I have to do is change the grid tie inverter for a charge controller and bring in the batteries, stand alone inverter and not have to completely rewire everything from the solar panels to the inverter, possible future charge controller area.
I want to use big 72 cell panels, 260 to 310 watts each wiring them 2 in serries, probably put 4 or 6 panels per ground mount station.
But I'm not sure which grid tie inverter I should get.
Most of the 48v grid tie inverters I find are micro inverters and appear to be junk. A lot of these 48v micro inverters dont look like they could handle the power from two 300w panels in serries.
All the big inverters I find are for high voltage only.
Is there a reasonable 2kw to 6kw 48v to 240v grid tie inverter out there that I'm just not finding?

mcgivor · June 2018

Finding a grid tied inverter with such a low voltage input will be tough, most are above 100V, the lowest I've seen is 70V. Micro inverters are designed to use the output of a single panel, located at the panel, not for series panels. The voltage of two 24V nominal panels in series would be ~ 72Vmp, 86Voc not 48V, the reason a sting inverter uses higher input voltages are for both convenience and economic reasons and generally 550V maximum probably due to the 600V ratings of many panels, a guess, it certainly has nothing to do with high voltage which is >1500V for ripple free DC . There are many solutions using commercially available components which would make things simple, why the resistance?

mike95490 · June 2018

You need to look for the Hybrid Inverters, they run off batteries, have internal transfer switches, and will provide you with whole house UPS if that's where you are heading for.

Schneider's XW series, Radian, and others meet your requirements - BUT they need a minimal battery bank to function, larger batteries if you want household backup.

Drawbacks - some models don't handle exporting to gird well if L1 & L2 legs are not well balanced.

oil pan 4 · July 2018

I was looking for something that would do grid tie and provide useable 120v AC power with no batteries and no grid input signal when the power goes out.
I found the sunny boy sps serries, a grid tie that works off 125 to 550v DC input power. Which will provide up to 1,600w 120v 60Hz power straight from the solar panels, with no batteries and no 60Hz grid signal. As long as the panels can support the load.

I would like a big expensive hybrid system but it's just not in the budget yet.

mike95490 · July 2018

oil pan 4 said:

I was looking for something that would do grid tie and provide useable 120v AC power with no batteries and no grid input signal when the power goes out.
I found the sunny boy sps serries, a grid tie that works off 125 to 550v DC input power. Which will provide up to 1,600w 120v 60Hz power straight from the solar panels, with no batteries and no 60Hz grid signal. As long as the panels can support the load.

I would like a big expensive hybrid system but it's just not in the budget yet.

I believe that the island power feature, is:

1) limited , not the full inverter capacity, and if a shadow goes by, will shut off

2) is manually activated when the grid goes down, you have to manually flip a switch to energize the 1 power outlet.

Dave Angelini · July 2018

SMA calls it "secure power" and it is only secure when the sun is out. (no storage for night). It is in their TL Inverters and I am not sure of newer model names.
As Mike said the earlier model required a person to flip the switch when the grid goes out.
One of my clients said that a model is on the tracks soon that will switch on the 120vac receptacle when the Utility dies.

littleharbor2 · July 2018

Dave Angelini said:

SMA calls it "secure power" and it is only secure when the sun is out. (no storage for night). It is in their TL Inverters and I am not sure of newer model names.
As Mike said the earlier model required a person to flip the switch when the grid goes out.
One of my clients said that a model is on the tracks soon that will switch on the 120vac receptacle when the Utility dies.

And don't you have to manually switch it off as well to get the inverter back online?

Dave Angelini · July 2018

Not the TL series my brother has. Installed 3 years ago.

cow_rancher · July 2018

It sounds like you could jury rig a simple relay-contactor combination to do the flip of the switch when the grid goes down, it could be engineered to not automatically come back up when the grid returns, or it also could be automatic. That may void the SMA warranty.

Rancher

mike95490 · July 2018

It's not so much the flipping of a switch, but the power is only fed to a local outlet on the inverter, it does not wire to your electrical panel. You still have to run an extension cord to the beer cooler

oil pan 4 · July 2018

> @mike95490 said:
> oil pan 4 said:
>
>
> I was looking for something that would do grid tie and provide useable 120v AC power with no batteries and no grid input signal when the power goes out.
>
> I found the sunny boy sps serries, a grid tie that works off 125 to 550v DC input power. Which will provide up to 1,600w 120v 60Hz power straight from the solar panels, with no batteries and no 60Hz grid signal. As long as the panels can support the load.
>
>
>
> I would like a big expensive hybrid system but it's just not in the budget yet.
>
>
>
>
>
> I believe that the island power feature, is:
>
> 1) limited , not the full inverter capacity, and if a shadow goes by, will shut off
>
> 2) is manually activated when the grid goes down, you have to manually flip a switch to energize the 1 power outlet.

That is what I was thinking and expecting.
I'm good with just the one outlet for now.
I have generators and 2 smaller 12v inverter rigs so this wouldn't be the only backup power I have.

Multi Kw 48v to 240v grid tie inverter?

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