Do Hybrid Inverters pull from Grid/Solar/Battery at the same time?

[bob.longmire]

Do inverters take from all 3 sources at once to get to their maximum AC Output potential?

In a simple example, if I had 2 EG4s, in parallel, with a total AC output of 13,000 Watts could that come from 4,500 watts of solar, 1 LifePower4 outputting of 4,300 watts from the battery (until it's depleted), and the remaining 4,200 Watts come from the Grid?

I know the real world is never this clean, but do the inverters "Mix" power from multiple sources? Or, in my example, would the inverters see the load requested is 13,000 Watts, realize the battery can only output 4,3000, and then turn to the grid to get all 13,000?

Thanks for the help!

 

[robby]

I know that Sol-Arks can do that.
I can only speak about my experience with Sol-Ark Inverters.
It will combine PV and Battery to satisfy the Load. You can limit the maximum amount of battery power you want to contribute based on the time of day or set it to max available.
If the PV and Battery are not enough then it will draw from the Grid and combine all three. If you are off grid or have a blackout and have a Generator it will start the Generator and use that instead of the Grid. If you tell it to save the battery for use at night or only during power outages it will combine PV and Grid or PV and Generator power. When the PV exceeds what is needed by the Loads it will use the excess to charge the batteries, if a cloud passes over and the PV drops it will once again use battery or grid power to supplement, depending on how you set it up.
Also in off grid situations you can tell it to switch on the Generator to charge the batteries if they drop below a certain level. When Grid tied you can use the Grid to charge the batteries if they get below a certain level.

BTW this is done very "Clean". As the home owner you do not even notice any changes as it moves between or combines different power sources.

 

[timselectric]

My Growatt can share the loads between solar and grid, or solar and battery. But not grid an battery.

 

[Mattb4]

You have to be in parallel with the grid for any sharing to occur. Output from an inverter is AC but input is DC. Load sharing in parallel AC circuits will depend on on the grid tie inverter limits.

Hybrid inverters come in two flavors: Grid tie and off grid.

 

[timselectric]

You have to be in parallel with the grid for any sharing to occur. Output from an inverter is AC but input is DC. Load sharing in parallel AC circuits will depend on on the grid tie inverter limits.

Hybrid inverters come in two flavors: Grid tie and off grid.

Grid-tied inverter is not required for sharing the loads between grid and solar. (And I don't see any reason why this couldn't happen with Battery also. My unit just doesn't have the option in the settings)
My Growatt SPF-5000-ES is an off grid AIO.
It has this functionality. It's called SUB mode.

 

[bob.longmire]

Thanks everyone! I'm reading through the manual of the EG4 6500 EX-48, and I don't see it mentioned if they have this ability like Robby's Sol-Ark does or if they are more like TIm's Growatt's.

Anyone know the specifics for the EG4 6500 EX-48?

 

[timselectric]

Thanks everyone! I'm reading through the manual of the EG4 6500 EX-48, and I don't see it mentioned if they have this ability like Robby's Sol-Ark does or if they are more like TIm's Growatt's.

Anyone know the specifics for the EG4 6500 EX-48?

I don't believe that it has either option.
I think that it's grid or inverter.

 

[Clifton]

Do inverters take from all 3 sources at once to get to their maximum AC Output potential?

In a simple example, if I had 2 EG4s, in parallel, with a total AC output of 13,000 Watts could that come from 4,500 watts of solar, 1 LifePower4 outputting of 4,300 watts from the battery (until it's depleted), and the remaining 4,200 Watts come from the Grid?

No, they are off grid that will switch to grid pass through once battery voltage is too low based on your setting.

I should say that with a 280ah 48v battery bank (diy) I can run a lot, even in the evening with low or no solar without worry. Not 13k and I would never push them that hard but 6k watts is not on timers and can come on while in straight battery or batt/solar and I'm good until my low volt switch over. If you are going to run two of these, I would not use one 5.1kw battery. I don't think you'll be happy and you'll be murdering it with the high charge and discharge.

 

[Mattb4]

Grid-tied inverter is not required for sharing the loads between grid and solar. (And I don't see any reason why this couldn't happen with Battery also. My unit just doesn't have the option in the settings)
My Growatt SPF-5000-ES is an off grid AIO.
It has this functionality. It's called SUB mode.

Incorrect. If your AC sources are not in parallel than no sharing occurs. Yes you can power loads either by solar/battery or AC utility. But not both together. A transfer from one source to the other must occur. The fact that it is done in 10ms by some of the units does tend to make it seem seamless. But to say they are sharing the load is not factually accurate.

 

[Vigo]

This thread in its first 9 posts would have saved me a lot of time if i'd read it a year or so ago.

 

[bob.longmire]

Ha! I'm hoping to save myself some troubles, too! Vigo, given what you've learned, do you think the Growatt 5kW Stackable inverters may be a better fit for me than the EG4s given my desire to have more load sharing between AC and DC inputs? I'm in the market for the all in 1 hybrid solutions that don't cost a fortune. The Sol-Arks are nice, but they're super expensive. Any suggestions or tips?

 

[RCinFLA]

Some can do this but most of the low cost HF inverters cannot because they switch battery to high voltage DC converter mode between supplying AC output (DC boost) and charging batteries (DC buck). This takes a small amount of time (20-100 msecs) so they cannot change from charging battery to supplying AC load from battery power quick enough to immediately pick up an AC load shaving demand from battery power. They can AC load shave from PV power up to point of available PV power.

Deye and SolArk HF inverters have a large bank of high voltage DC storage capacitors to supply the power during the battery to HV DC converter mode switchover. They can do AC load shaving.

LF hybrid inverters are inherently bi-directional so can do immediate AC load shaving pickup.

Any hybrid inverter that allows battery power to supplement AC input power for AC output loads will have a user setting for limit on AC input amps draw so it knows where to begin the battery powered AC output load supplementing. This is very useful when using a generator for AC input allowing AC loads greater than can be supported by either the generator or inverter alone.

Some model inverters have additional firmware features that allow this to be determined by time of day so they can do it based on Time of Use (TOU) for time of use utility grid cost scheduling. You select a tariff plan where you pay more for grid power used during peak utility load time of day and supplement your usage from your batteries and/or PV during this period, then during off peak times you pay less for grid power. In this case, inverter may try to totally power your loads from battery and only takes power from grid when your AC loads exceed capability of inverter (or your battery gets low).

 

[Vigo]

I don't know anything about the EG4s but I do know that the only way to get the Growatts to do what you want is to NOT parallel them, split your AC loads between them, and each set of loads would be limited to 5kw from each inverter.

If you parallel the growatts, they will BOTH switch over to grid when the load exceeds your solar+batt energy, at which point your battery is doing NOTHING to support the loads, but will be being charged by the grid until the inverter switches 'back to battery'.

So you can't have AC + Batt load sharing with 2 growatts in parallel.

If you keep them OUT of parallel but still sharing the same battery, and place a limit on the 'charge from grid' current (setting #2), and set their source priorities (setting #1) so that one is in SUB and other one is in Solar First or SBU or simply not connected to grid at all, what could conceivably happen is that the solar first/no-grid inverter could be doing 4kw of work with 1kw of solar and draining battery by 3kw, while the SUB/grid-connected inverter is charging battery with 1kw of solar and 1kw from grid. In that scenario your battery is only draining by 1kw instead of 2kw, and you are buying 1kw from grid rather than the 2kw you'd be buying if inverters were in parallel and switched to grid+solar. But this setup i feel is rather poor because it limits both sets of load to 5kw from the individual inverters.

What might be cheaper and better would be to simply have a grid battery charger turn on and off based on the dry contacts of the inverters. The growatts can switch their dry contacts based on 'switch from battery to grid' and 'switch from grid back to battery' voltage setpoints. If the inverters themselves are not actually connected to the grid I believe these contacts will still switch even though the inverter itself is not actually switching to grid (i have not verified this). If you use those contacts to activate a grid-powered battery charger, the effect would be "if battery voltage drops below X, charge battery from grid until voltage rises to Y, then stop". The actual amount of grid charging would be set by whatever charging setup you build to accomplish this.

Or you buy an inverter that does all of this internally and buy once cry once!

The ironic thing is that buying an SPF5000ES purely as a 48v 80a battery charger and not using its inverting capability at all, is probably not much if any more expensive than buying a dedicated 48v 80a battery charger by itself..

 

[Sebanavila]

I know that the Volctronics Axpert Max II does it, at least the European models, but they are only Off-Grid inverters.

 

[timselectric]

Incorrect. If your AC sources are not in parallel than no sharing occurs. Yes you can power loads either by solar/battery or AC utility. But not both together. A transfer from one source to the other must occur. The fact that it is done in 10ms by some of the units does tend to make it seem seamless. But to say they are sharing the load is not factually accurate.

Sadly, it's you who are mistaken.
I know how my system works. lol

 

[Vigo]

I had no idea how much of the things i would want to end up knowing about my inverter or other inverters came down to their internal electrical architecture. Despite teaching electrical fundamentals as part of my job, i am VERY FAR from an EE.. more like a kid asking 'why' to everything, or at least my internal dialogue is! RCinFLA's explanation was very helpful. The way i understood that is that there is only ONE large 'buck/boost dc-dc converter' in a lot (all?) of these inverters, which is used for both grid-to-battery charging, and battery-to-inverter ac output. I would have previously assumed they were two separate components.

If that's the case then it makes sense why you can't charge from grid without going into ac bypass on my inverters, because the dc-dc would be in use going from grid to battery, and not available to go from battery to inverter. It's just too bad that my 2 inverters in parallel can't just decide that one will stop inverting and NOT go into bypass to grid charge battery, while the other inverts from battery. It would further be nice if, in parallel, i could hook a different AC input (because none of my inputs are actually the grid!) to each inverter and have them retain different 'charge current limits' from each other. So if i do something like turn on a small generator to one, it stops inverting and grid charges at a low current limit while the other keeps inverting. If i plug a large generator or large inverter into the other one, it stops inverting and grid charges at a high current while the other one keeps inverting.

The weakness of ALWAYS going from battery to fully 'on grid' as far as the input is concerned, is that what i have hooked up to the input can't always support the full load of the running inverter! Cliffnotes is it forces me to use an external charger to duplicate a task the inverter is already capable of, and limits what can be hooked to the ac input to something large enough to carry the full load.

This is probably only really desirable to me because this has been a 'summer of experimentation' where i tried feeding anything and everything to my inverters, right way, wrong way, you name it. Eventually I would settle on a semi-permanent arrangement and not care so much about the ease of setup and teardown of the various inputs i've tried. But it would still be nice if the settings let me try my goofy ideas a little more easily...

 

[Vigo]

Sadly, it's you who are mistaken.
I know how my system works. lol

I think it's a simple mistake of wording.

It should be "you can power loads either by solar+battery or solar+utility. But not battery+utility together."

 

[Mattb4]

Sadly, it's you who are mistaken.
I know how my system works. lol

But do you understand parallel AC generation and load sharing? In order for two supplies to feed one load in AC they must be in parallel. No if, buts or sorry.

It is the same in DC but parallel in DC is easier since you have no alternating current to deal with. You can hook two batteries together in parallel so long as the voltages are the same and no explosion happens. Try that with AC and you will let out the magic smoke.

 

[Mattb4]

I think it's a simple mistake of wording.

It should be "you can power loads either by solar+battery or solar+utility. But not battery+utility together."

The only way solar and utility can work together to power loads is the solar to AC inverter must parallel with the AC utility supply.

Sorry to harp upon this but it is an important part of understanding different load sharing setups.

ETA: Incidentally requirements of parallel AC sources are why the so called zero grid export units are just about impossible to not export some to the grid as loads change. I expect at some point utility companies will take a hard look at people doing this without an interconnect agreement.

Back when I was in the Navy one of my jobs was to parallel large 3 phase diesel and steam turbine driven generators. We did not have all the electronics that matched phase availble today and had to use synchronizing lights and meter. If you did not get darn close when you shut the supply breaker for the incoming generator you would get a large bang as the two sources came together. You then had to pick up the load or balance it between the two generators depending on each generators ratings.

 

[PuraVidaPrepping]

Ha! I'm hoping to save myself some troubles, too! Vigo, given what you've learned, do you think the Growatt 5kW Stackable inverters may be a better fit for me than the EG4s given my desire to have more load sharing between AC and DC inputs? I'm in the market for the all in 1 hybrid solutions that don't cost a fortune. The Sol-Arks are nice, but they're super expensive. Any suggestions or tips?

GSL energy offers units similar to the Sol-Ark (based on the original Deye design), and they are now distributing in the USA, but at lower cost than Sol-Ark. Software isn't as sleek, but the hardware is solid.