Connect them where the external CTs for the grid connect. The UI menu would tell the Sol-Ark if the CTs are deployed to the Grid or the Gen input.
Sol-Ark no longer supporting gen shave
- Thread starter Cmiller
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RCinFLA
Solar Wizard
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Because a generator AC input port must not allow back fed power there is no advantage to having CT sensor outside of inverter.
For practicality, it is bit better to put gen port CT sensor internal to ensure it works properly to prevent back feed then rely on installer/user getting the external CT sensor hookup correct. It is too easy to put CT sensor over sensed wire backwards. Long, poorly dressed CT output sense wire pairs affects the measurement accuracy of phase and current. Correct phase relationship to AC voltage is critical to determine power flow direction.
Factory can better calibrate an installed given internal CT sensor then rely on separate external CT sensor with its random make tolerance accuracy.
Inverters with external CT sensor capability usually hold a reserve margin on sensed current of a few amps positive power from utility incoming power to ensure accuracy limitations of external CT sensor power flow direction and magnitude measurement does not result in some grid back feed power when zero grid export is set in inverter.
Sol-Ark already supports and recommends generator connected to the grid using external CTs. Doing the same on the Gen input wouldn't be different. AFAIK Sunsynk doesn't have any internal CT on the Gen input and they support Gen peak shaving using external CTs. Gen peak shaving is a setting in Powerview.
IIRC way back before the Sol-Ark 15K was available, there was a time when you could use the external CTs for gen OR grid (on the 12K). But only one, of course, not both.
If this were still an option, then it would open up the possibility of at least choosing to use the CTs on either gen or grid. Whichever makes the most sense, or is most needed for the specific application. In a "whole house backup" scenario, using a 15K with the full 200A service passing through the inverter, there is no benefit to having the external CTs hooked up on grid wires. Then, using the CTs for gen would be perfect!
If this were still an option, then it would open up the possibility of at least choosing to use the CTs on either gen or grid. Whichever makes the most sense, or is most needed for the specific application. In a "whole house backup" scenario, using a 15K with the full 200A service passing through the inverter, there is no benefit to having the external CTs hooked up on grid wires. Then, using the CTs for gen would be perfect!
This is true except for the fact that the Sol-Arks don't limit the draw from the generator. Schneider, Outback, Magnum, etc. all have either input amps or breaker size setting. This allows the inverter to dynamically control power being drawn from the gen. E.g. as loads go up, the inverter dynamically controls the charge rate to keep the amps flowing into it at the setpoint that it has been configured to, and to avoid overloading the gen.
Since the Sol-Arks no longer have gen shave option due to apparently not being able to properly "read" power flowing into the gen terminals, the external CT sensor option would be of immense value!
Your statement is true in the sense of an internal CT inside the inverter being perfectly suitable for this! The issue here seems to be a lack of a suitable internal CT.
The external CT sensors currently coming with the Sol-Arks do need to be installed correctly. But this goes for any CT sensor application that is to read bi-directional current! The bigger, reputable, name-brand AIOs such as Sol-Ark, Eg4 (18kpv), LuxPower, etc. all come with external CT sensors that are optional. The instructions for setting them up always mention that they have to be installed correctly to work right! With external CT sensors, you get additional features, at the cost of having to install the optional CTs correctly. To me this is a very small cost for the added benefits available!
The Sol-Ark inverters have a setting to set the minimum draw from grid between 0-500 watts. Even when set to 25 or 50 watts there tends to be some short spikes of power that flow back to grid. I am sure that even clouds passing in front of the sun can affect the power flow enough to make it hard for the inverter to respond quickly enough!
Thanks for that! Although it looks like it is a 2021 document, so I don't believe that gen shave is able to use the external CT sensors anymore. I could be wrong though, so I might give it a try to see for sure.
Even if it is accessible through PowerView, almost for certain access will be gone when we migrate to MySolArk monitoring in May.
Teprewitt
New Member
You stated that in off grid you can use grid peak shaving to limit gen draw. So when the gen is connected to grid input you turn off “gen peak shaving” and select “grid peak shaving?” I am having an issue where the inverter is overloading the generator even though I have Gen peak shaving set at 12,000 watts for a 14,000 watt generator. I spoke with tech support and they went through my system but due not change the Gen peak shaving to grid peak shaving.
Brucey
Solar Wizard
Which generator specifically? Perhaps 14kw surge with a lesser continous rating?
DIYrich
Solar Wizard
On your Basic Setup screen, Advanced tab, what is you Gen Limit Power setting?
Teprewitt
New Member
Generac 14k. It states its 14k operating wattage, but I have it set to 12k limit.
Teprewitt
New Member
12,000.
DIYrich
Solar Wizard
On the Limiter screen, Other tab, "gen connected to grid" checked?
Sudden draw on generator? do you have Eco mode off (or whatever similar setting)?
Teprewitt
New Member
Yes, Gen connected to grid is checked. My AC units are soft start units that ramp up slowly. The generator is being kicked off when the inverter tries to pull over 14,000 watts when trying to supply power to an AC unit. The inverter never drops charging wattage, it tries to maintain the max charging amperage set in the battery settings no matter what the load is. Should it I have a 6,000 load, and max charging amperage set at 165, the generator is overloaded and the inverter kicked it off.
Gen shave doesn't work. Period.
I think it has to do with their hardware only monitoring a single leg and assuming the other leg's draw is identical.
To use Grid Peak Shave for a gen, you need to feed the gen into grid terminals, then check the "gen connected to grid" box. Then the inverter knows that there is a gen on the grid input.
Also, Generac's rarely work well to charge inverters. They simply don't have very good voltage control. They put out quite dirty power generally.
Another note. Generally on a 12kW standby gen (we use Kohler 14, rated for 12kW) you won't want to have your normal draw higher than 6-8kW. So if your gen is actually rated 14kW, I would recommend not going higher than ~8-10kW. This allows some room for surges etc. and will also give you more usable hours out of the gen vs. having it maxed out whenever it is running.
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Brucey
Solar Wizard
I think there was a discussion earlier that that setting is deprecated but still visible?
RCinFLA
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All hybrid inverters running in parallel with AC input source, whether high freq or low freg design, have an AC input tracking response time delay.
It is normal for grid voltage to fluctuate abruptly a few volts as neighborhood loads are turned on and off. These fluctuations will cause some current pushing and pulling on a parallel connected hybrid inverter while the inverter adjusts itself to match the AC input variations.
The primary difference is low frequency inverters are inherently bidirectional on power flow. You can see the effects of grid voltage fluctuations on battery current push and pull on low freq inverters. High frequency hybrid inverters are not inherently bidirectional and have to absorb grid short period voltage variations in their HV DC filter capacitors. This makes HF hybrid inverters more 'delicate' and vulnerable to damage from AC input voltage variations.
Waveform distortion from an old generator causes sinewave waveform mismatch between generator and inverter. The worse the generator's distortion, the higher the peak current spikes on the inverter due to instantaneous sinewave waveform mismatching. At some level the inverter will disconnect from generator due to excessively high surge currents.
Most inverters can tolerate quite a bit of AC input distortion. Most often, generator governor control engine rpm stability is the reason for inverter releasing from generator. Too much rpm variation on a synchronous generator means too much frequency/phase variation for inverter to track the AC input sinewave phase locking. Frequency/phase tracking control loop in hybrid inverters are purposely very slow responding.
Unfortunately, unless someone is running very old firmware, the gen shave function no longer is capable of using the external CTs! It uses only the internal CTs, and as far as I can see on the circuit board, the internal "CTs" consist of a single CT, presumably monitoring only the amps draw of one phase. Therefore phase imbalance between L1 and L2 causes massive swings in the functionality of "gen shave" specifically.
Grid Peak Shave on the other hand, uses the external CTs. And it works quite well.
DIYrich
Solar Wizard
Assuming you can live in the 12-14kW limit of the inverter, the next best option is to use 2 Chargeverters to directly charge the battery. Constant 8kW load on the generator.
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