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

[Mattb4]

Correct,
My only point was that it doesn't have to be a grid-tied inverter to do this. Because mine does, and is not.

Which model of inverter do you own?

 

[timselectric]

I have the Growatt SPF-5000-ES.
It has SUB mode. (Solar Utility Battery)
In this mode it parallels the AC source with the inverter output. Solar provides its full available power and the AC source covers the rest of the loads. In this mode it starts by pulling the first 500w from AC source. (To avoid any exporting) then it uses all available solar. If solar doesn't cover the rest of the loads, the AC source covers whatever is left. It works just like grid-tied with zero export, in this mode. The difference is that it doesn't require a constant AC source to run.

 

[Danke]

I went through the same. Every time I thought I had found a lower cost solution/inverter, I would find SOMETHING that was a major con for either my current application, or a future needs/wants. I also waited months for new products to be released, or for them to be proven in the field. For months and months, everything either proved to be riddled with issues, would be out "very soon" (and also likely to also have teething issues), turned out to be false hopes, etc. Couple this with most of these products having little to no domestic (US) based CS, TS, or reasonable and quick avenue for service and I found myself asking "what was I really gaining by saving a few thousand on the heart of the system by going with these lower cost options?"

After almost a year of waiting for something to meet all of my needs, have excellent CS, TS, and true domestic service, all at a lower cost, I finally realized I'd be money and time ahead just biting the bullet on a Sol-Ark 15k. It was possibly close to 2x what I wanted to spend, but SA is well sorted, it offered a much easier installation (with no CLP/sub-panels), the 200A bypass (no need for the ATS) and whole house BU, massive AC and DC coupling, lower cost battery options, all the features I could ever dream of, a ten year warranty, and possibly the best 24/7 domestic service one could ask for. And again, a ton of room for growth and configuration options, basically unmatched by anything else.

Yes I paid more for the SA, but when I look back at all the stuff I read about, waited for, and fretted dealing directly with China over, I wish I never considered anything else... just to save a little (possibly only short-term) money. As stated earlier, pay now, or pay more later... sometimes it's a lot easier to just do it right the first time, and I now think that's the case (at least for me anyway) with inverters. IMO the SA is a no-brainer, even for the additional $. YMMV...

And if you can, take 30% off, then the 15k doesn’t sting as much. Heck, get another one as a back up! ?

Mine should come out to be $5670 each, delivered.

 

[timselectric]

So i suppose i don't understand how this works:

I understand what you mean about 2 AC sources must be in parallel.
I NOW understand the concept of the one shared buck/boost converter..
I know that the mppt output is a DC source.
I know that when my Growatt is using ac input for anything, it's in bypass/passthrough and i assumed that meant the inverter output was physically open-circuited to the ac output terminals by the transfer switch relay..

But if all that is true, then how would the DC solar be used to 'load shave' the AC? The only way i see that being possible is if the inverter is in fact still inverting, frequency-matching and phase-syncing to the AC input (which we know it does all the time anyway), and then paralleling to the AC input.

Which in theory means it WOULD have a connection back to grid (if ac input was grid), and then the only thing making it 'zero export' aka off-grid (am i using these wrong?) is the software managing it. Hardware wise something like flipping off the main breaker on the output, or grid side going down because a lineman is wanting to work on something next door, would seem to me like it would result in 'export' if the software did not react fast enough.

Correct

and is this why so many cheap inverters are called 'off grid', because hardware wise they can't prevent grid export and so can't hit some regulatory threshold for legally being connected to grid?

Off grid inverters do not need an AC source (the grid) to operate. They usually have a battery component.
Grid-tied inverters require an outside AC source to function.
Hybrid inverters are a combination of many functions. Of one or both types.

 

[timselectric]

And if you can, take 30% off, then the 15k doesn’t sting as much. Heck, get another one as a back up! ?

Mine should come out to be $5670 each, delivered.

My 30k worth of inverters (with the 30% rebate) will be a total cost of $4k.

Under $5k, with a spare inverter sitting in the closet.
And the only thing that I can't do is export to the grid. (Which I have no interest in)

 

[Mattb4]

I have the Growatt SPF-5000-ES.
It has SUB mode. (Solar Utility Battery)
In this mode it parallels the AC source with the inverter output. Solar provides its full available power and the AC source covers the rest of the loads. In this mode it starts by pulling the first 500w from AC source. (To avoid any exporting) then it uses all available solar. If solar doesn't cover the rest of the loads, the AC source covers whatever is left. It works just like grid-tied with zero export, in this mode. The difference is that it doesn't require a constant AC source to run.

So it is in parallel (grid tied). You will find that your zero export is inaccurate. I can believe it can run without the grid. All of these inverters have the option to use solar and battery power.


Do you have an interconnect agreement with your utility? Any time the unit is in parallel with the grid it can export to it.

 

[timselectric]

So it is in parallel (grid tied). You will find that your zero export is inaccurate. I can believe it can run without the grid. All of these inverters have the option to use solar and battery power.

Yes , in parallel.
Similar to grid-tied, but not. It's only one way. It keeps a 500w load from the grid. (To accommodate for surge, and reaction time)

Do you have an interconnect agreement with your utility? Any time the unit is in parallel with the grid it can export to it.

Not necessary, for an off grid inverter that can't export.

 

[Vigo]

Off grid inverters do not need an AC source (the grid) to operate. They usually have a battery component.
Grid-tied inverters require an outside AC source to function.

Good point. I had forgotten about that trait of many 'grid tied' inverters.

Although i suspect it's not so much that the inverters 'require' the ac source to function (f they do have batteries?), so much as to guarantee that they aren't exporting into a grid that is not supposed to be 'live' because utility turned it off. It is probably a safety feature that facilitates utility operators being willing to approve of installations more than a requirement of the inverters themselves. That's my assumption based on what i know right now. What I know has already changed several times in this thread.. which is excellent.

 

[RCinFLA]

I have reservations with the SolArk 15K 200 amp transfer switch. Transfer switches take a beating from grid glitches.

They open every time there is a grid glitch that causes a surge overload on inverter, so they open the contacts under the surge current limit of inverter, which for 15K inverter is spec'd as 30kVA, or for 240vac, is >125 amps of current through relay when relay contacts open up. Very tough on relay contacts.

My system probably averages three to five grid glitch induced pass-through relay cutouts a week. Florida has a lot of thunderstorm induced grid glitches.

I am very interested in someone posting a picture of this 200 amp transfer switch.

I personally would never count on my total 200 amp grid connect service to feed through the inverter pass-thru relay.

 

[Mattb4]

Yes , in parallel.
Similar to grid-tied, but not. It's only one way. It keeps a 500w load from the grid. (To accommodate for surge, and reaction time)

Not necessary, for an off grid inverter that can't export.

But it can export. Likely it is exporting under certain conditions. The techniques it uses to overcome exporting are not the same as not being in parallel provide.

Vigo is right about grid tie inverters. They look for a AC signal so that they can go into parallel and start sending current. No utility AC they stop working. However they also could be zero export if the house loads exceed what they can provide. But you have to remember that in parallel it is not just house loads that are seen . Every load the utility is connected to being supplied by the power sources as a percentage of their output. So Hoover dam is sending 99.9999% of the load but your little solar grid tie is picking up .0001%. If loading changes than every supply of AC must also change.

Here is where it becomes meaningless to say that your grid connected inverter is zero export. As I frequently have commented it is always about the loads. Supply does nothing until a load happens. Two supplies hooked together divide up the amount of load just like 2 batteries hooked together divide up the current demand. If one source of power has a higher potential it picks up a higher percentage of the load until the potential equalizes.

In the world of paralleling diesel generators you increase the fuel to one generator to pick up more load. In the world of riding a tandem bicycle if one peddler is lazy the other has to increase the force they exert to keep moving.

 

[sergea]

I have the Growatt SPF-5000-ES.
It has SUB mode. (Solar Utility Battery)
In this mode it parallels the AC source with the inverter output. Solar provides its full available power and the AC source covers the rest of the loads. In this mode it starts by pulling the first 500w from AC source. (To avoid any exporting) then it uses all available solar. If solar doesn't cover the rest of the loads, the AC source covers whatever is left. It works just like grid-tied with zero export, in this mode. The difference is that it doesn't require a constant AC source to run.

in fact you have double conversion in place on some voltronic base. ACin -> DC + solar DC => DC_to_ACout .

ACin is never connected to ACout, @Mattb4 is right ;-)

​

.

 

[Mattb4]

in fact you have double conversion in place on some voltronic base. ACin -> DC + solar DC => DC_to_ACout .

ACin is never connected to ACout, @Mattb4 is right ;-)

​

.

Ah... so the utility AC is simply putting out more DC to the inverter alongside the DC from solar and battery. In that case it is not grid tie and would not require an interconnect agreement. There never is any parallel happening on the AC side.

 

[sergea]

Ah... so the utility AC is simply putting out more DC to the inverter alongside the DC from solar and battery. In that case it is not grid tie and would not require an interconnect agreement. There never is any parallel happening on the AC side.

yep, they are off grid inverter ;-)

 

[sergea]

yep, they are off grid inverter ;-)

and this double conversion is necessary to get the 0 delay transfer switch on some model

 

[LeoThomson]

Have a look at the Victron Multiplus II.

MultiPlus-II - Victron Energy

The MultiPlus-II is ideally suited for professional marine, yachting, vehicle and land based off-grid applications. Learn more now.

www.victronenergy.com

 

[Vigo]

they open the contacts under the surge current limit of inverter, which for 15K inverter is spec'd as 30kVA, or for 240vac, is >125 amps of current through relay when relay contacts open up. Very tough on relay contacts.

I personally would never count on my total 200 amp grid connect service to feed through the inverter pass-thru relay.

I agree.. as an automotive tech i have dissected many high current solenoids and the durability of ANYTHING not-solid-state switching 100+amps at a high duty cycle is dubious. I understand AC will result in a sort of natural termination of an arc after 1/60th of a second or so under normal circumstances, but in my mind it's the fact that the arc started at all which creates the damage..? Still, if you think about starting your car at least twice a day, it is still usually years before those solenoids become intermittent. I have not seen the 200a transfer switch but all the pictures ive seen of other inverters with smaller pass through current ratings looks like a regular 30-40a relay housing which have MUCH smaller contacts than a starter solenoid. Like.. 1/50th the surface area. So i would expect to see something more along the lines of size of a starter solenoid to expect it to be 'reliable' at 100+ amps..


The contacts of failed high current solenoids I have taken apart look like the surface of the moon! Just pounded up dust and craters.
However.. I have not dissected a starter solenoid from a vehicle with auto stop-start. Now it is common for vehicles to switch that ~100-400a starter circuit solenoid dozens if not hundreds of times per day. Considering the high current solenoid contacts were already the main failure point of starter motors to begin with, I'm curious what they've done to make them reliable. I have learned about some of the internal changes of 'enhanced flooded lead acid batteries' to make starter batteries more resilient under the new usage regime, but never heard anything about changes to the solenoid..

 

[robby]

I agree! I have no regrets spending on my Sol-Ark 12k. I was looking at my notifications yesterday, and realize my system hasn't had a fault or reboot since June 2021..... I service a lot of different systems, but nothing "just works" like the Sol-Ark.

Same here,I think it was July 2021 when it was commisioned and since then it just sits in the utility room and powers the house. We have had several blackouts and did not even notice. The AC's and rest of the house run all night on batteries and in the morning the sun comes out just in time to take over and start powering the house and charging back the batteries.
A totally seamless operation.

 

[schmism]

I know that when my Growatt is using ac input for anything, it's in bypass/passthrough and i assumed that meant the inverter output was physically open-circuited to the ac output terminals by the transfer switch relay..

I suppose that depends on the model your talking about.

The growatt SPF3000TL (the version I have) will only share between solar and battery. If your on grid, it does not use the inverter.

as an example, 2500w of load 1000w of solar It will pull 1500w of energy from the battery.
if it has transitioned to the grid and there is a 2500w load it pulls 2500w from the grid.

 

[timselectric]

in fact you have double conversion in place on some voltronic base. ACin -> DC + solar DC => DC_to_ACout .

ACin is never connected to ACout, @Mattb4 is right ;-)

​

.

I don't believe that is the case. If it were going through the DC bus. It would be able to share the loads between grid and battery. Which it can't. I believe that it is paralleling AC in with the inverter output. I say this because the bypass relay doesn't change state between bypass and SUB mode.

 

[sergea]

I don't believe that is the case. If it were going through the DC bus. It would be able to share the loads between grid and battery. Which it can't. I believe that it is paralleling AC in with the inverter output. I say this because the bypass relay doesn't change state between bypass and SUB mode.

of course it is available on some model only. there is never ACin paralleling on ACout on off grid voltronic inverter.

 

[Vigo]

I suppose that depends on the model your talking about.

The growatt SPF3000TL (the version I have) will only share between solar and battery. If your on grid, it does not use the inverter.

as an example, 2500w of load 1000w of solar It will pull 1500w of energy from the battery.
if it has transitioned to the grid and there is a 2500w load it pulls 2500w from the grid.

Now that you mention it, I think the only times I ever experimented with the AC input while the sun was still up was when I first got the inverters set up back in May.. it’s possible I’m misremembering what actually happened those months ago. ?

I have no grid connection whatsoever and since my system has ‘excess’ power during the day and it’s 100 degrees outside, i dont turn off my inverters (aka the ac!!) to run experiments until there is no solar energy left to play with.

Now i doubt my memory enough that i will make no further assertions about what it does or doesnt do in that regard unless ive got fresh experience..

 

[timselectric]

of course it is available on some model only

I'm not sure how other models work. But I have figured out how mine works.

 

[sergea]

I'm not sure how other models work. But I have figured out how mine works.

you're still right on the fact that it can't work with utility and battery at the same time to power the load. The note about MAX capability to power the load with any 1 or 2 combinations of any input is in contradiction with the documentation. I have a PIP-MAX in a box, I'll give a try.

 

[timselectric]

The note about MAX capability to power the load with any 1 or 2 combinations of any input is in contradiction with the documentation.

Where did you see this note?
I don't remember seeing this anywhere in my manual.

 

[sergea]

you're still right on the fact that it can't work with utility and battery at the same time to power the load. The note about MAX capability to power the load with any 1 or 2 combinations of any input is in contradiction with the documentation. I have a PIP-MAX in a box, I'll give a try.

ok, when utility is involve to power the load, battery can only be charge. can never have utility and battery at the same time to power the load.
ACin is connected to ACout only in line mode., it is just a bypass.