sunny boy inverter?

[SunEagle]

Not all GTI enforce UL GTI specs so it depends on the GTI. I know it's not easy to AC couple GTI that's why I said none of this is for uninformed readers. And yes, I have successfully AC coupled to GTI (UL and non-UL) with different inverter types.

Actually you are making an incorrect statement and may have an illegal system if you live in the USA. To be legal in the USA your solar equipment must carry a UL certification or the POCO & AHJ will not approve it. Sure if you live up in the wilderness and the nearest town is miles away you can try to get away with anything you want but it may not be safe or legal should you try to sell the place.

[solardreamer]

How do you propose to AC couple without complying with the UL spec of the GT Inverter? Hybrid is a loose definition so you can call it "grid forming inverter" but the procees of doing it safely implies more than just providing a sine wave. It requires firmware implementation that is not trivial. AC coupling is understood and used commonly to refer to that process. The GT inverter changes its output in response to voltage and frequency variations in a specific way. Have you AC coupled to a GT inverter sucessfully?

Not all GTI enforce UL GTI specs so it depends on the GTI. I know it's not easy to AC couple GTI that's why I said none of this is for uninformed readers. And yes, I have successfully AC coupled to GTI (UL and non-UL) with different inverter types.

[SunEagle]

yes, i wired it in when i installed it, however the max is 2kw i believe

But the power the SMA secure outlet provides is not consistent based on the varying sunlight and therefore should be used only to charge a battery or run a non critical load.

Oh and is UL compliant and legal to use in the USA.

[mudhole]

Of course, you know that a -41 SMA inverter has a built in off-grid capability called "Secure Power Outlet". Most installers will include it as it just entails a regular 20amp recepticle wired into the inverter and a switch to activate this mode when the grid is down. Provides up to 15amps of power as long as there is enough sun on your array to support it...

yes, i wired it in when i installed it, however the max is 2kw i believe

[mudhole]

Question for @mudhole? What kind of inverter do you have? I thought you mentioned it had generator input. If so, is it capable of operating off grid?

no, i have a separate generator, i have the sunny boy 5.0-41

[solarix]

Of course, you know that a -41 SMA inverter has a built in off-grid capability called "Secure Power Outlet". Most installers will include it as it just entails a regular 20amp recepticle wired into the inverter and a switch to activate this mode when the grid is down. Provides up to 15amps of power as long as there is enough sun on your array to support it...

[Ampster]

Question for @mudhole? What kind of inverter do you have? I thought you mentioned it had generator input. If so, is it capable of operating off grid?

[Ampster]

Let's stipulate none of this should be attempted by uninformed readers and anyone doing this should do the homework to understand the potential risks for a particular system. Depending on the particular setup and/or local AHJ rules, the grid forming inverter does not necessarily have to be a hybrid inverter or UL compliant.

How do you propose to AC couple without complying with the UL spec of the GT Inverter? Hybrid is a loose definition so you can call it "grid forming inverter" but the procees of doing it safely implies more than just providing a sine wave. It requires firmware implementation that is not trivial. AC coupling is understood and used commonly to refer to that process. The GT inverter changes its output in response to voltage and frequency variations in a specific way. Have you AC coupled to a GT inverter sucessfully?

[solardreamer]

[QUOTE=mudhole;n423807]

You are defining what a hybrid inverter does when it AC couples to a GT inverter. So the word "decent" should be changed to hybrid and furher clarified by saying UL compliant..
Otherwise uninformed readers could think this is simple when indeed it is complicated. The word fake is also misleading because what a hybrid inverter does is emulate the grid but replaces the infinite load that the grid presents with the controls that the hybrid uses to vary the output of the GT inverter according to the loads on the system.
To answer your subsequent question using a proper hybrid inverter wired correctly is how it has been done and is currently being done. The most current UL spec is UL 1741 SA.[/QUO

so lets say i decide to do another array, i dont want the upkeep of batteries etc, but want to have full power when the sun is shining and it be GT...what i need is to purchase a hybrid inverter, and in the event of loss of grid , i could get both arrays to function?

I share your desire to not have to deal with battery upkeep. However, what you want is something lots of others want but no one sells such solution as far as I know. A few commercially available systems can provide full power from GTI without batteries while disconnected from the grid but without batteries the power can be extremely unstable. Think what happens with passing clouds or even birds while you have loads connected.

[solardreamer]

You are defining what a hybrid inverter does when it AC couples to a GT inverter. So the word "decent" should be changed to hybrid and furher clarified by saying UL compliant..
Otherwise uninformed readers could think this is simple when indeed it is complicated. The word fake is also misleading because what a hybrid inverter does is emulate the grid but replaces the infinite load that the grid presents with the controls that the hybrid uses to vary the output of the GT inverter according to the loads on the system.
To answer your subsequent question using a proper hybrid inverter wired correctly is how it has been done and is currently being done. The most current UL spec is UL 1741 SA.

Let's stipulate none of this should be attempted by uninformed readers and anyone doing this should do the homework to understand the potential risks for a particular system. Depending on the particular setup and/or local AHJ rules, the grid forming inverter does not necessarily have to be a hybrid inverter or UL compliant.

[Ampster]

.......

so lets say i decide to do another array, i dont want the upkeep of batteries etc, but want to have full power when the sun is shining and it be GT...what i need is to purchase a hybrid inverter, and in the event of loss of grid , i could get both arrays to function?

You could get some hybrids to provide power from only its array without batteries. Not all hybrids work without batteries. However to AC couple with a GT inverter, with any sucess, you would need batteries. The batteries are important to provide the buffer needed to control the GT inverter. The best answers are available by reading the specifications of different hybrid inverters. You should become informed about the technicalities of AC coupling. There are no simple solutions. AC coupling and faking the grid are two entirely different things.

[mudhole]

[QUOTE=Ampster;n423806]
You are defining what a hybrid inverter does when it AC couples to a GT inverter. So the word "decent" should be changed to hybrid and furher clarified by saying UL compliant..
Otherwise uninformed readers could think this is simple when indeed it is complicated. The word fake is also misleading because what a hybrid inverter does is emulate the grid but replaces the infinite load that the grid presents with the controls that the hybrid uses to vary the output of the GT inverter according to the loads on the system.
To answer your subsequent question using a proper hybrid inverter wired correctly is how it has been done and is currently being done. The most current UL spec is UL 1741 SA.[/QUO

so lets say i decide to do another array, i dont want the upkeep of batteries etc, but want to have full power when the sun is shining and it be GT...what i need is to purchase a hybrid inverter, and in the event of loss of grid , i could get both arrays to function?

[Ampster]

Yes you can with any decent pure sine inverter but you need a system that can handle the max watts from all grid tied inverters in your system and you will need to manage excess PV production ....

You are defining what a hybrid inverter does when it AC couples to a GT inverter. So the word "decent" should be changed to hybrid and furher clarified by saying UL compliant..
Otherwise uninformed readers could think this is simple when indeed it is complicated. The word fake is also misleading because what a hybrid inverter does is emulate the grid but replaces the infinite load that the grid presents with the controls that the hybrid uses to vary the output of the GT inverter according to the loads on the system.
To answer your subsequent question using a proper hybrid inverter wired correctly is how it has been done and is currently being done. The most current UL spec is UL 1741 SA.

[mudhole]

Just remember, when faking a Grid with a small inverter, if you solar array is producing 4,000 watts and you are only consuming 2,000 watts, something is going to happen.

Whatever happens, be sure you understand how your small inverter will respond if it suddenly sees 2000 watts coming into it. Will it shut off ? Will it try to frequency shift to control the larger inverter ? Will the larger inverter respond appropriately ? Will all the magic smoke inside be released ?

great questions to have to think through, are there inverters that have safety switch built in that would cut off in the event you stated?, to bad you cant feed back from the solar array once it was activated to mimick the grid line. How has this been done in the past?

[SunEagle]

Don't see anything illegal. It's all done while disconnected from grid. grid tied inverters work just fine with full power provided you have appropriate equipment for an island grid. Just look at Tesla Powerwall when it's disconnected from the utility grid.

Unless your system is a hybrid with a battery trying to make a grid tie inverter work fully without the grid can be dangerous and possibly illegal depending on what your POCO and AHJ have approved. Making changes to the inverter to fool it to think the grid is ok is dangerous and IMO illegal.

Completely disconnecting from the grid and having your solar charge a battery or power a small load through a special power connection is ok. As you say having the proper equipment to be an island grid is the way to go in the first place.