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

[Salts]

My system consists of a 10.7kw array using two Sunny Boy Grid Tied inverters. Normally, we just pump power to the grid through our net metering with the utility.

Yesterday, a big storm knocked out almost 500,000 customers in the south eastern Michigan area, including my home. Been without power for 30 hours now.

My emergency off-grid backup system uses two Sunny Island 6048 inverters and a 16.5kw Lithium Ion battery pack I salvaged from a Chevy Volt.

This is the first real test I've run with this system since I built the off-grid portion late last year. In 2019, we lost power 7 times for an average of 3 days.. So I built the off-grid system. Since it was completed, we have only lost power once for like 3 hours so not much use out of it. Funny how that works eh?

When we lost power yesterday, I simply went down stairs, flipped the required breaker interlocks to isolate ourselves from the grid, and turned on the Sunny Islands. The house had immediate power and within a couple minutes, the solar array started making juice as well. Since I store the batteries at 50% DOD for extended life, we only had about 5kW of juice to work with until this morning when the sun came back up.

Then the magic happened. The solar array started making full power, charged the batteries all the way up to their set-point, and then something amazing happened.. The Sunny Islands went into what they call "Frequency Shift Power Control" and started throttling the output from the solar array.

This is an amazing thing to see. We have a full sunny day and my big solar array is only putting out 1.2kw of power because the batteries are fully charged and the house isn't drawing anything but a little juice for the fridge and freezers.

I'm over here turning on lights and fans just to use some extra energy...

To see it for the first time is just so cool.

[solarix]

Yes, I call Sunny Island the Cadillac of hybrid solar systems. Not cheap though!

[Salts]

Yes, I call Sunny Island the Cadillac of hybrid solar systems. Not cheap though!

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.

[Salts]

Yes, I call Sunny Island the Cadillac of hybrid solar systems. Not cheap though!

Per your signature line, I'm upgrading my 16.5kw Chevy Volt batteries and going to be using Chevy BOLT batteries. 40kw worth.. Just haven't finished putting them together yet.

LG Chem cells are the best in the world.

[sabersix]

I'm interested to see how you have this setup. Can you post a diagram and/or some pictures of your setup?

[Salts]

I'm interested to see how you have this setup. Can you post a diagram and/or some pictures of your setup?

Which part?

There really isn't much to the system. The Grid Tied Sunny Boy's are hooked up like every other solar array and feed power into my circuit breaker box. Nothing at all different there.

Then I have a large box (3ft x 4ft x 22 inches deep) that contains my battery and BMS. The positive and negative from the bats connect to the Sunny Island (SI) inverters. About the only significant difference with mine is that the SI inverters are not hard-wired to my breaker box, I connect the system with a 6ga 4 wire SO cord so that the inverters are totally isolated when not being used. I just connect the cord, flip an interlock breaker that isolates the grid, and I'm up and running.

I didn't hard wire them in as normal for fear that a lightening strike could destroy my expensive equipment.

Here's a diagram of how they are normally hooked up. Its pretty straight forward.

sunnyisland.jpg

[sabersix]

I have the Sunny Boy solar system, so I'm familiar with that part. This Sunny Island battery system that works with the Sunny Boy solary system when disconnected from the grid is intriguing. As you know, the Sunny Boy normally just has the 1000w secure power supply that provides some power from the panels when disconnected from the grid.

If I'm understanding this correctly, the Sunny Island will access the full power of the Sunny Boy solar system to charge the battery bank. Between the SI and SB, the load from the home is met and any excess power is directed back to the batteries. What happens when the battery bank runs low at night? How do you keep the batteries charged when totally isolated? Why would the SI system be anymore sensitive to lighting than the SB system?

Pictures would be great if you don't mind sharing.

[Salts]

I have the Sunny Boy solar system, so I'm familiar with that part. This Sunny Island battery system that works with the Sunny Boy solary system when disconnected from the grid is intriguing. As you know, the Sunny Boy normally just has the 1000w secure power supply that provides some power from the panels when disconnected from the grid.

If I'm understanding this correctly, the Sunny Island will access the full power of the Sunny Boy solar system to charge the battery bank. Between the SI and SB, the load from the home is met and any excess power is directed back to the batteries. What happens when the battery bank runs low at night? How do you keep the batteries charged when totally isolated? Why would the SI system be anymore sensitive to lighting than the SB system?

Pictures would be great if you don't mind sharing.

Yes, the Sunny Islands (SI) make a grid-quality power which causes the Sunny Boy's to think the grid is active and they start making power as well. The SI will use excess power from the SB to charge batteries. If the batteries are already charged and the SB are making too much power for the loads, the SI will throttle the SB through Frequency Shift Power Control. (No special hardware needed).
When my 16.5kw bats came to full charge, the SI units initiate the Frequency shift and the SB inverters were only allowed to make just enough power to keep the house going. The system works amazingly well. When my 240 well water pump kicked in, the lights in the house didn't even flicker..

If your battery bank runs dry at night, (which should not happen with a properly designed system), then the SI units can automatically start a generator to power loads and charge the batteries.

The Sunny Islands are no more or less sensitive than the Sunny Boy inverters as far as I know.. they're just a hell of a lot more expensive, and since I have the option to isolate them when not being used, I do it.
By isolating the off-grid system, not only would it save the Sunny Islands, but it would also save the $800 BMS..

I'll have to work on photos.. had to dump my computer.. running on different system right now until I get a new motherboard. Every 4 years like clockwork.

[rmusada]

If we use the Sunny Island 8.0H we don’t need other controller to regulate PV the balance between the energy feed in and energy used ? Our set up is PV grid tie with 10Kw panel using 2 Sunny Boy Inverter. We want to go off grid. What is the maximum size of the generator that we can connect to a Sunny Island 8.0H ?

Thank you.

[Salts]

If we use the Sunny Island 8.0H we don’t need other controller to regulate PV the balance between the energy feed in and energy used ? Our set up is PV grid tie with 10Kw panel using 2 Sunny Boy Inverter. We want to go off grid. What is the maximum size of the generator that we can connect to a Sunny Island 8.0H ?

Thank you.

The maximum solar energy that can be fed through them isn't as much about the Sunny Island as it is the battery bank. I think the Sunny Islands are limited to 140 amps per 6048, but you'd have to check on the 8.0H... But that's their limit, not your system limit.. your battery will probably be far more restrictive. For example, I have two Sunny Island inverters (6048) and two Sunny Boy (6kw) grid inverters on a 10.7 kw system. When I go into off grid mode, I turn off one of the Sunny Boy inverters, which cuts my solar array almost exactly in half to around 5.4kw. This limits the power being delivered to the 24.5kw Lithium battery bank. 480 amp hours of battery can only accept about 80 amps of charge before it starts to generate heat, and heat is bad. And lead acid batteries will start to gas if you charge them too fast as well.

Now, that said, if I go off-grid during cloudy dark skies, and if I need more solar power, I just flip the 2nd Sunny Boy on.. Due to the FSPC (Frequency Shift Power Control) which the Sunny Islands use to control the Sunny Boy's (a sort of throttling of their solar output power), there's a lot of over-lap of when I should and shouldn't use the 2nd array. The amount of sunshine and the SOC of the battery bank and our current load useage, all make a difference if I want the engine room to deliver max warp speed.

So really, it depends mostly on your battery bank.

If you have a Sunny Island, a Battery bank, and a grid tied inverter, that's all you need.

[Ampster]

When both GT inverters are connected do they modulate or cycle on and off? I wonder if it is headroom on your batteries? For example, if you started out the day with a lower SOC on your batteries if the GT inverters could run full warp? Or are you approaching the full charging capacity of your pack?

[Salts]

When both GT inverters are connected do they modulate or cycle on and off? I wonder if it is headroom on your batteries? For example, if you started out the day with a lower SOC on your batteries if the GT inverters could run full warp? Or are you approaching the full charging capacity of your pack?

My pack is a 480ah Lithium (Chevy BOLT cells) configured 14s8p (or is it 8p14s?) and it can take a 1C charge rate, so theoretically, they could take everything both GT inverters can produce and more. Problem is, that would generate a lot of heat... heat bad. very bad.

When the pack is full, the Sunny Island's start to throttle the active SunnyBoy with FSPC.. and my house only draws about 500 to 800 watts most of the time. Even with just one inverter turned on under full sun, the frequency ends up in the 61.8hz to 61.9hz range. Just 0.1 hz higher and and the inverter will trip out. Sometimes I have to start turning stuff on just to prevent it.

This is only an issue on cool summer days.. in the winter, I just plug in a space heater. The Sunny Islands have a load dump option just for this purpose, I should probably hook it up.

[Ampster]

Thanks that was helpful. I guess there is no modulation, just on or off for the GT inverters.
The reason I am asking is I am getting ready to AC couple my Solar Edge GT inverter to my Outback Skybox and was trying to anticipate any issues when off the grid. I currently have four Enphase IQ-7s AC coupled and they do modulate depending on the load and the batteries thirst for energy.

I am expecting the SolarEdge will also modulate since they are fairly recent firmware. We are moving into the time of year that we will have expected power outages and i have a new pack. I am expecting that it will get me through a couple days with no sun, but I want to have all the available solar available for charging if there is sun.

[Salts]

Thanks that was helpful. I guess there is no modulation, just on or off for the GT inverters.
The reason I am asking is I am getting ready to AC couple my Solar Edge GT inverter to my Outback Skybox and was trying to anticipate any issues when off the grid. I currently have four Enphase IQ-7s AC coupled and they do modulate depending on the load and the batteries thirst for energy.

I am expecting the SolarEdge will also modulate since they are fairly recent firmware. We are moving into the time of year that we will have expected power outages and i have a new pack. I am expecting that it will get me through a couple days with no sun, but I want to have all the available solar available for charging if there is sun.

I'm not entirely sure what you mean by "modulation". But if I get you correctly, then YES there IS modulation. When the batteries start to approach full charge, the Sunny Islands raise the frequency to 61.1 hz. This causes the Sunny Boy GT inverters to reduce they're output power by 10%. For each 0.1hz above 61hz, the GT inverters will reduce by another 10%. At 62hz, they trip on over-frequency. This is FSPC (Frequency Shift Power Control) that is employed by the Sunny Islands to throttle (modulate ?) the GT output power.

For example, when my batteries were at 98-99% SOC, and my home was pulling about 700 to 800 watts, the Sunny Island inverters were holding the frequency at around 61.8 to 61.9 hz... this caused the GT inverter, under full sun with 5.4kw of panels, to only produce about 700 to 800 watts.

There's a limit to FSPC.. Its like trying to make your car go 0.5 miles per hour... its difficult to do that.

[Ampster]

Yes that is exactly what i mean by modulation.