No he is using two grid tied inverters but they have backup outputs so can work off grid BUT he is using the backup output of one to form the grid for the other one
Will it work? Supplementing off grid inverter/battery with on grid PV inverter in one system.
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zanydroid
Solar Wizard
But they’re inverters designed to AC couple (in both roles presumably based on my quick perusal of the growatt docs) while a lot of questions from OP seem to be around using arbitrary random off grid inverters.
timselectric
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Exactly
They are capable of handling input from the other.
timselectric
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It's one thing to use a hybrid inverter for off grid.
And an entirely different thing to try to use an off grid inverter as a hybrid.
And an entirely different thing to try to use an off grid inverter as a hybrid.
How do you arrive at this conclusion? I don't see anything in the manual that says they are capable of a coupling. Maybe I'm missing it
They are not specified for that, that I know of
timselectric
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They are grid-tied units. (Bidirectional, by design)
So where does the power go when the battery is full, with a grid tied unit?
timselectric
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Hopefully nowhere.
If it's controlled well. There shouldn't be any incoming power.
But when the batteries are not full, everything is fine.
That can't be said for an off grid inverter.
zanydroid
Solar Wizard
Here is the combiner box
SYN 200-XH-US | ESS Accessories | Growatt
SYN 200-XH-US | ESS Accessories | Growatt
Check the inverter number, I might have it wrong
MIN 3000-11400TL-XH-US | Residential Storage Inverter | Growatt
MIN 3000-11400TL-XH-US | Residential Storage Inverter | Growatt
zanydroid
Solar Wizard
I’m not sure I’m down with including AC coupling as a standard feature of hybrid. Mine is more minimal: AIO+grid tie approval.
EDIT: that means stuff like grid assist, an actually flexible, working, and useful TOU config or other PCS feature set are optional.
timselectric
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Hybrid, is the combination of grid-tied and off grid capable.
Grid-tied, has bidirectional capability. And the safeties for handling input without damage. As long as it has somewhere to put it. (Batteries that aren't full)
zanydroid
Solar Wizard
I guess my concern with that definition is that AC coupling still feels like it’s not a proven feature on all things that might be called a hybrid. I’m not even sure it’s required by UL1741SB for this class of device. I don’t think it’s required for grid safety or stability while anti islanding, frequency watt, ride through, and PCS are (well PCS is more helping with the grid business model and not safety)
So by leaving it out of the presumed feature set people that use my definition are encouraged to do their own research on the spec sheet and manual.
If it is defined as mandatory by a standard then I can immediately accept that, maybe, unless there is deviation from the zeitgeist definition.
For sure grid assist and quick turn around between inverting and charging mode cannot be included in presumed feature set.
So by leaving it out of the presumed feature set people that use my definition are encouraged to do their own research on the spec sheet and manual.
If it is defined as mandatory by a standard then I can immediately accept that, maybe, unless there is deviation from the zeitgeist definition.
For sure grid assist and quick turn around between inverting and charging mode cannot be included in presumed feature set.
zanydroid
Solar Wizard
Actually, thinking about switching between charger and inverter mode. How does HF topology simultaneously charge while generating AC for the GTI to follow? The main power transistors will be needed by the charger.
I guess my theories as a non EE are:
1. switching frequency of the ideal rectifier transistors is enough to magically tickle the GTI the right way
2. they must use a bidirectional DC DC converter so do not really switch modes
3. there is a secondary set of lower power transistors to enforce the frequency
2.?
I guess my theories as a non EE are:
1. switching frequency of the ideal rectifier transistors is enough to magically tickle the GTI the right way
2. they must use a bidirectional DC DC converter so do not really switch modes
3. there is a secondary set of lower power transistors to enforce the frequency
2.?
zanydroid
Solar Wizard
Isn’t that just an AIO?
I doubt the forum zeitgeist would accept that as a definition of hybrid. Since otherwise why have two words
timselectric
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AC coupling capable is a two part feature.
Bidirectional capable and the ability to control.
You don't need full AC coupling capable, to safety receive power.
The downstream unit needs to be able to be controlled. Either by the upstream unit. Or by a separate device.
What I'm getting at is that the downstream unit can be set to zero export. And anything that slips through, won't damage the upstream unit, if it's capable of receiving the power.
So, while AC coupling would be the best choice.
It's not required, as long as both units are capable of doing their parts.
An off grid unit, isn't designed to receive any power from its grid forming side.
timselectric
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apctjb
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For sure, but what if it suffers no damage? It is not bi directional but does it matter if no damage occurs and the downstream unit throttles sufficiently to avoid voltage rise that could damage loads on the panel?
Dumb question, does AIO means all in one and if so what are the functions necessary to be considered a AIO?
timselectric
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Then you can consider yourself lucky.
You're definitely welcome to spend your money however you choose. We are just trying to help you not spend it twice.
Yes, All In One.
AIO
Inverter
Solar Charge Controller
AC charger
Transfer Switch
Hybrid AIO
All of the above + grid-tied
zanydroid
Solar Wizard
Off-grid behaves as a standard AC voltage source. Logically speaking you can think of the GTI as a blend of a variable AC voltage source that attempts to be constant power when attached to another voltage source it is following.
If you have 500w of load and 3kW of GTI where does the 2.5kW go? The GTI is designed to shift its output voltage and phase until 3kW makes it out. It most likely will not make it to 3kW before anti-islanding or exceeding over-voltage ride through cutoff but if it manages to push out 1.5kW that's still 1kW going somewhere bad.
The majority of voltage drop on the loads will be in the loads. Some loads will consume more power with higher voltage, but it will most likely not be enough to compensate. That leaves the AIO as the most likely victim for the output power to go. If the AIO outputs 240V and the GTI cuts off at 250V then you might end up with 10v across some wires or components in the AIO. Basically turns those wires into heaters during the time until GTI cuts off.
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