I'm absolutely amazed at how well Sunny Island inverters work.

[Rimcanyon]

I'm curious why you don't have the Sunny Islands setup so that they are running in grid-tied mode too? I am currently looking at adding battery backup to my system (Sunny Boy 4000TL with 4.2kW of Sunpower X21 panels), and the configuration I am planning is also using SMA equipment: an SMA ABU, an SMA Sunny Boy Storage 6.0 and a BYD Battery Box. I like the ABU because of the way it governs the system in grid-tied mode, so as solar power output is going down at the end of the day it pumps battery power into the grid (up to the legal maximum), maximizing return from the time of use rate structure. The ABU also has an automatic transfer switch, so utility power down and up events are handled automatically. In off-grid mode battery and panel output are not throttled (except as needed to avoid overcharging batteries), so full power is available.

[Salts]

I'm curious why you don't have the Sunny Islands setup so that they are running in grid-tied mode too? I am currently looking at adding battery backup to my system (Sunny Boy 4000TL with 4.2kW of Sunpower X21 panels), and the configuration I am planning is also using SMA equipment: an SMA ABU, an SMA Sunny Boy Storage 6.0 and a BYD Battery Box. I like the ABU because of the way it governs the system in grid-tied mode, so as solar power output is going down at the end of the day it pumps battery power into the grid (up to the legal maximum), maximizing return from the time of use rate structure. The ABU also has an automatic transfer switch, so utility power down and up events are handled automatically. In off-grid mode battery and panel output are not throttled (except as needed to avoid overcharging batteries), so full power is available.

We don't keep the Sunny Islands connected for personal application reasons. The primary concern is that I don't want a lightening strike to take out my ridiculously expensive inverters and battery management system, so with that in mind, we keep them isolated from all four lines (L1, L2, Neutral, Ground) until the system is needed. The second reason is that the Sunny Islands are designed in such a way that you either need a "critical loads panel", which doesn't power the whole house, or a very expensive transfer switch. Neither of these was appealing to me as both added significant costs and rewiring work as well as more wall space for the extra hardware.

When we go into off-grid mode, we have full power to the entire home. Nothing changes other than a 3 minute blackout while the system is manually turned on. The outputs of the Sunny Islands feed right back through the main breaker panel. In fact, I usually need to turn off one of the solar arrays because the Sunny Boys make a lot more power than we actually use during most of the year. Last time we used the system, the solar array was throttled down to 61.8hz, so only 0.2hz from tripping out. I had to turn on fans and the television just to draw a bit more juice.

[z80]

We don't keep the Sunny Islands connected for personal application reasons. The primary concern is that I don't want a lightening strike to take out my ridiculously expensive inverters and battery management system, so with that in mind, we keep them isolated from all four lines (L1, L2, Neutral, Ground) until the system is needed. The second reason is that the Sunny Islands are designed in such a way that you either need a "critical loads panel", which doesn't power the whole house, or a very expensive transfer switch. Neither of these was appealing to me as both added significant costs and rewiring work as well as more wall space for the extra hardware.

When we go into off-grid mode, we have full power to the entire home. Nothing changes other than a 3 minute blackout while the system is manually turned on. The outputs of the Sunny Islands feed right back through the main breaker panel. In fact, I usually need to turn off one of the solar arrays because the Sunny Boys make a lot more power than we actually use during most of the year. Last time we used the system, the solar array was throttled down to 61.8hz, so only 0.2hz from tripping out. I had to turn on fans and the television just to draw a bit more juice.

I do it differently...I run off grid all the time...with the grid connected to the generator input of the Sunny Island.

So there is no dead time...in fact we often see neighbours dark and only then realize grid has gone down.

Grid charges the batteries only when all else has failed...no sun..batteries down...evening.

We also have cheaper power tarriffs so I installed a timer which further limits when the errr..."generator" can supply power.

I now have 5 sunny islands in two locations, guy who sold me 3 of them had them ina 3 phase setup....somebody convinced him to toss it out and buy two Powerwalls......FAIL

[Murby]

I do it differently...I run off grid all the time...with the grid connected to the generator input of the Sunny Island.

So there is no dead time...in fact we often see neighbours dark and only then realize grid has gone down.

Grid charges the batteries only when all else has failed...no sun..batteries down...evening.

We also have cheaper power tarriffs so I installed a timer which further limits when the errr..."generator" can supply power.

I now have 5 sunny islands in two locations, guy who sold me 3 of them had them ina 3 phase setup....somebody convinced him to toss it out and buy two Powerwalls......FAIL

Our current net metering rules make going off grid financially stupid.. but that will change in 2027 when my 10 years is up and they change the net metering rules. Hopefully, by that time, there will be a lot more electric vehicles sitting at the salvage yards with nice healthy batteries.

[solardreamer]

Ya, the retail price north of $5,000 is kind of hard to justify.. Got two of them on ebay for $2200 ($1100ea) shipped to my door. My only mistake was not buying 4 of them. I kick myself now.

Are they used?

[Murby]

Are they used?

Brand new.. even came with the 10 year extended warranty which I verified with SMA via the serial numbers.

They were the result of a company called DC Solar going out of business because the company was a scam. The courts liquidated the company and dumped around 20,000 Sunny Islands onto Ebay.

[z80]

Brand new.. even came with the 10 year extended warranty which I verified with SMA via the serial numbers.

They were the result of a company called DC Solar going out of business because the company was a scam. The courts liquidated the company and dumped around 20,000 Sunny Islands onto Ebay.

You are sure it was twenty thousand sunny islands?
I call BS on that....sorry.

[Murby]

You are sure it was twenty thousand sunny islands?
I call BS on that....sorry.

Oops.. extra zero thrown in.

Here's the news release on it. The Sunny Islands were on ebay for months selling like hot cakes. GAGlobal auction sold most of their trailers (2 of the SI's on each), then more of the SI's new in boxes.

https://pv-magazine-usa.com/2019/05/28/dc-solar-gets-liquidated/

https://www.solarpowerworldonline.com/2019/05/dc-solar-auction-includes-unopened-solar-panel-pallets-combiner-boxes-sma-inverters/

[LeeLewis]

Maybe I'm missing it in this thread but are your inverters AC or DC? I cannot tell from the image, it's too small on my screen.
I have a grid tied 10.5KW system that I want to manually switch to batteries during extended outages. I don't want to tie it to the house, just its own breaker box and outlets from that.
My system however uses AC inverters so I'm trying to find a device similar to what you're talking about that would 'simulate' the grid so the solar system would keep running without connection to the grid. I'm looking online at Sunny boy devices mentioned but you've all mentioned a number of devices. I'll likely buy something older to save money. I don't need the full 10.5KW, 5KW or so would be plenty.

[z80]

Maybe I'm missing it in this thread but are your inverters AC or DC? I cannot tell from the image, it's too small on my screen.
I have a grid tied 10.5KW system that I want to manually switch to batteries during extended outages. I don't want to tie it to the house, just its own breaker box and outlets from that.
My system however uses AC inverters so I'm trying to find a device similar to what you're talking about that would 'simulate' the grid so the solar system would keep running without connection to the grid. I'm looking online at Sunny boy devices mentioned but you've all mentioned a number of devices. I'll likely buy something older to save money. I don't need the full 10.5KW, 5KW or so would be plenty.

The sunny island system is an AC coupled system.
There are no seperate DC charge controllers or all the other goo that some systems like Victron need.
As others have said..you mount the SI on the wall...connect red and black to the battery bank, mount a sunny boy next to it,
hook them up with a common AC connection and Voila....it just works.

I cannot believe the rats nest mess that Victron systems need to manage all the functions that a sunny island does internally.

As for your idea about simulating the grid, no way you will ever get that to work, many have treed, many have had a big bang.
Reason is the grid is an infinite load whereas a battery bank is not.

Bite the bullet, commit to doing it properly and just buy a Sunny island. with at least one Sunny Boy...and get the 8.0H.

At least a 5kw Sunny Boy, older ones don't work...make sure it has a "TL" suffix in the model number.

enjoy...

[LeeLewis]

Thanks.

I don't mean simulate the grid as in some kind of hack, I mean I've seen to many videos where solar installers are talking about devices that accept the solar AC input and uses the batteries to keep the solar system generating even if the grid goes down.

I'm having a heck of a time (learning) finding out what that kind of device is called since I'm not looking for DC to AC inverter with batteries but something that will accept the AC coming from the solar system and keep it running.

[SunEagle]

Thanks.

I don't mean simulate the grid as in some kind of hack, I mean I've seen to many videos where solar installers are talking about devices that accept the solar AC input and uses the batteries to keep the solar system generating even if the grid goes down.

I'm having a heck of a time (learning) finding out what that kind of device is called since I'm not looking for DC to AC inverter with batteries but something that will accept the AC coming from the solar system and keep it running.

The only inverter that I know about is a Hybrid type which will either send AC to the main panel or DC to the batteries which could then send AC through an inverter to the specific loads.

I have not heard of an AC Hybrid inverter but then again with some of the new technology coming from Tesla and other battery manufacturers there may now be an AC Hybrid inverter.

[LeeLewis]

My problem is not knowing the terminology as I've not had to play with my solar yet.
I'd like something simple and legal because we are grandfathered into a special deal with the power company where we get a good rate on our excess power so don't want to mess that up.

I believe in order to not mess that up, I need to tap into one of the panels *before* it reaches the power companies locked boxes.
From that panel, I could take the AC output from the soar, run it through a device that would keep the solar generating when grid goes down.
I would only bother if there was an extended outage so a manual transfer switch would be just fine.

In terms of output, I just need a device that will allow a usable output and shut off or kill output if voltage/amps get too low.
This device is one I've yet to learn what it would be called. It's not an inverter, it's some sort of manager that would prevent low voltage from being output if the solar is not outputting enough.

In terms of output, I can use either AC or DC. If AC, I could simply run a 48VDC charger to charge up a 48VDC battery bank. I have DC to AC inverters.
Or I could convert the AC to DC to charge batteries so in this case, I guess I'd need some sort of charge controller.

So it sounds like I only need three devices but it sounds like there are some devices that have all this built into one box. You mentioned the Sunny Boy so I looked that up and I think that's what I'm looking for and has all three things I need. Again, all new to me so lots and lots of learning but these forums and folks like you are certainly helping a great deal so I thank you for that.

[Ampster]

Yes, what you need is a hybrid inverter which can AC couple to your existing grid tie system. Hybrid inverters use DC batteries to invert the DC to AC to create the grid forming features needed to AC couple as mentioned previously by SunEagle . Hybrids are not distinguished by DC or AC designations. They use and create both DC and AC depending on the mode they are in. There are many brands from Outback, Schneider; SolArk, SMA and others. All of those can be installed behind the meter in such a way that they should not disrupt your arrangement with your power company. It is important to understand the terms of your Net Metering Agreement so that you are in compliance.

[richmke]

Search for Solar Battery backup, a/c connected. You won't need a big battery, but you will need a battery. That is what generates the A/C to simulate grid connection for the panel. Inverter will be expensive.

BTW: You need something more than "just need a device that will allow a usable output and shut off or kill output if voltage/amps get too low." It also needs to be able to throttle the output of the panels if there is not enough load. When you are connected to the grid, the grid absorbs any excess. When you are off-grid, there is no where for the excess power to go.