Grid tie inverters info

Hello

Can anyone shed light on sunnyboy grid tie inverter ?

Here is what I would like to achieve. Use a grid tie inverter but disable the ability to send power to the grid. Can this function be disabled in sunnyboy or any other grid tie you know of? I am looking about 6 - 8KVA

Thanks

Not sure which Sunnyboy you have. Some of the SMA inverters have an secure power outlet where you could use that when the grid is down. At least use that to power some loads.

But, all Grid-Tie inverters need the grid signal to work(thus, grid-tie) at either 240v/50/60hz depending where your location. If no grid or it is down, you will be looking at a hybrid-inverter so it could be communicated to the grid-tie inverters by providing the signal it needs to work.

Something I wrote up yesterday about it with diagrams. Just missing the DC Coupling part. For you to keep using the Sunnyboy, it will be AC Coupling.


@SolarQueen from AlteStore has videos on Youtube about AC and DC Coupling.

I don't have sunny boy as yet, but i do have sunnyisland si6048. Was thinking of using sunnyboy so i can use by generated power directly and balance to charge the sunnyisland batteries. any ideas?

I see you got the SMA SI6048. That one doesn't have the secure power outlet when power goes out. It will required a battery to feed it. You will need the same model if you want to use it at 240v split phase, or use an auto transformer to make 120v to 240v.

The Sunnyboy will be able to communicate to the SMA si6048 via the frequency shifting method (but it needs the 240v signal--thus required two SI6048 or auto transformers). eBay still got a few SMA specials under $1500. It is an nice all in one solution. Just the cost turn many DIYers away.

Yes, you could technically use the Sunnyboy's secure power at 120v and charge the batteries during the outage.

Are you using the Si6048 off-grid now? How's the Si6048 connected? I am just assuming the setup as off-grid when answering your charging question.

Yes, its off grid now with batteries.

I am one to believe that the people that believe grid tied design is flawed. Imagine that you were living say in Puerto Rico after the earthquake. The gid is down, sun is shining, you have a 10KVA system and you cant use it because the grid is down. This should never be happening.
Should be a way to disable the ability to feed into the grid.

It looks like if you plan to use purely 120V with a single SI6048 like what you have now as off-grid configuration, you could get a newer Sunnyboy that has the Secure Power Supply(SPS) outlet and have an interconnect switch flip between grid(120v) to SPS outlet to charge the off-grid si6048.

For example:

Sunnyboy(240v grid tie)--->(Interconnect switch toggle between SPS and 120v source from the wall to the SI6048)--->Si6048(120v single phase)--->Batteries only con is you must flip the switch when the grid is down or get that auto-transfer relay to do the flip for you.

It is like AC coupling at other level from the equipment you have and still get charging power to the batteries. This will eliminate over-charging concerns and diversion loads. You consume what you products and still be truly off-grid without the grid's 240v/60hz signal.

Maybe some other SMA experts could help further on the gap of how long could the SPS outlet be running as off-grid mode?


https://files.sma.de/dl/15216/SI4548-6048-US-BE-en-21W.pdf page 18.

Super Fly said:

I am one to believe that the people that believe grid tied design is flawed. Imagine that you were living say in Puerto Rico after the earthquake. The gid is down, sun is shining, you have a 10KVA system and you cant use it because the grid is down. This should never be happening.
Should be a way to disable the ability to feed into the grid.

Click to expand...

Grid-tie is cheaper for consumers to save some money from the monthly bills. AC/DC Coupling would add another 20K to 40K of expenses on top of the typical 35K grid-tie installation. No consumer would go for that. Typically, it is an after-thought.

Super Fly said:

Hello

Can anyone shed light on sunnyboy grid tie inverter ?

Here is what I would like to achieve. Use a grid tie inverter but disable the ability to send power to the grid. Can this function be disabled in sunnyboy or any other grid tie you know of? I am looking about 6 - 8KVA

Thanks

Click to expand...

Why do you wish to use a grid tie inverter if you don't want to send power to grid. Wouldn't A Inverter/charger do the trick?

I was gonna say...... get with sma and order all the communications hardware and jumpers, etc. Update of firmware likely, and ac couple that bad boy/island combo. Midnite solar has a transformer amd enclosure for it that matches sunny island.

Here is what I would like to achieve. Lets say my panels are producing 3000 watts of power and the house is using 1000, I would like to have that additional 2000 go to charge the batteries that are connected to the sunny island.

What is the best way then to go about this?

Buy all the nescessary communications parts, hardware and a sunny boy and rock on. The sunny island is the absolute most tailorable piece of equipment i have ever handled.

Not 100% positive, but I believe Sol-Ark and a few other GT inverters have the ability to take power from the grid, but not to export solar power.

Absolutely you can use your sunny island and a sunny boy to do that. But are you totally off grid?
If so, i would never (almost never) introduce a sunny boy into the mix. Dc couple unless you want a mini grid with various houses or buildings sharing ac power for loads and battery charging.

Having a traditional solar dc charger and an inverter charger is much less cost intensive amd problematic.

kernel said:

Absolutely you can use your sunny island and a sunny boy to do that. But are you totally off grid?
If so, i would never (almost never) introduce a sunny boy into the mix. Dc couple unless you want a mini grid with various houses or buildings sharing ac power for loads and battery charging.

Having a traditional solar dc charger and an inverter charger is much less cost intensive amd problematic.

Click to expand...

Hi Kernel
No, I still have utility supply. What I am currently using is SI6048-US, MS Classic 250 MPPt Charge Controller and about 12KWh battery pack

Ah. Yup to backfeed you would want a sunny boy(s) (microinverters?), transformer, web box, cards and comm cables.

And this is for everybody here...... if you want to just know directly, what you need from a manufacturer to get their tech up and running, call them and ask. They want to sell and understand thet instlers amd users will need to know more.

Unfortunately for some, the details are likely in the manual. Start with the warnings and glossary of terms. Then the overview and system operation details.

Its usually in there, but if you are really not speaking the language (toughest barrier) a talk with a rep or applications engineer is in order before buying.

Next talk to the outlet you buy from, as the same general questions with your new knowledge in pocket. I sometimes glean really great info from unlikley salesmen resources..... but usually not precise details. You can rarely ask these people "what do i need" and the engineers will want to know what youn are looking at and what you need it to do.

With sma, call them and give them your model and serial data and simply ask them what parts are needed in your case.

Diversion loads and or remote operated breakers* might be integrated in order to accomplish with grace though.

I never understood sma on that one. They have good reason, you may want component isolation.

For me a dc coupled battery based grid interactive inverter charger is the go to device in 98% of installs. That may not be true for all. The cost for grid interactivity is nil or next to nil once you are at a certain $/quality level they all start at about 1600$ so we use them off grid as well. Dual ac inputs is a gift from the engineers on high! Highly programable interfaces with multi mode, no brainer....

With regular pv charge controls dc coupled, the excess power is exported to the grid through the inverter that would be idle instead of two whole inverters.