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mmx01 avatar image
mmx01 asked

Total AC output power EasySolar II GX 24/3000

Hi,


I plan to use EasySolar II GX 24/3000 to power a small cabin. Typically the AC load is not very high +/- 1000W but on occasion I may have heater and electric kettle on which adds to about 4000W.


My question is, is it mandatory to get 48/5000? Or perhaps 24/3000 would still work because power limit is only for DC->AC converter and I could still draw another 3600W (16A) via ACin mains connection. Here I am not that clear about overload conditions vs. combining ACin (3600W) + DC->AC (3000W) out for a total power of 6600W in short moments with these high power loads on.


The system will be EasySolar, 2,2kw solar, 2x280 24V LifePo4 battery. I read that EasySolar is combination of few other systems like MultiPlus II + MPPT etc. In theory I can go to 48V with batteries in series but I already have 24V stuff and prefer to keep the system at 24V.


Thanks in advance,

Mariusz

powerassist
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4 Answers
matt1309 avatar image
matt1309 answered ·

Hi @mmx01


I'm not familiar with easysolar but multiplus ii manual comments on this exact scenario.

And im pretty sure easysolar is really just a multiplus ii + mppt isnt it?


Assuming you have a grid connection (with ESS or power assist setup i believe). Then you should be fine. The manual explains it from point of view of a 3kva multplus ii.

MultiPlus-II 230V (victronenergy.com)

Page 14 in the above (AC-out-1) section.


EDIT:

Found in easysolar manual same page number

EasySolar-II GX - Product Manual (victronenergy.com)


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mmx01 avatar image
mmx01 answered ·

@matt1309 this is excellent! Indeed currents add up. Please let me know if I understood this right.


I connect mains to AC in and the rest of the system to the inverter.

Since I do not plan to feedback anything to the network nor applying for any permits certificates, need to set zero feed-in options. It also says I don't need meter to make it work. Correct?

Grid Feed-in :

AC coupled : disabled

DC coupled: disabled


Enable ESS assistant, do not enable PV assistant since MPPT is DC coupled and not AC coupled.


Then to maximize solar usage I use Virtual Switch - Ignore AC:

- Load conditions: >2800W for 10 sec & < 2500W for 60 sec -> system will not use AC below 2800W just solar + battery. When load goes >2800W AC in helps with the load.

- Battery voltage: <25.2V for 60 sec -> system will start charging battery and providing assist on low battery.


Is there a way to set priority between solar and battery? Looks like ESS in Optimizer mode works like that: Yes. ESS will reduce grid usage to a minimum, preferably to 0W, with or without feed-in enabled. It keeps the MPPT Solar Chargers working hard - even when the batteries are full. -> So the answer seems to be as long as solar has enough power it will provide load first and then charge battery?


It is a very complete system but a bit difficult to understand interlocks between different parts/document at first glance.

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matt1309 avatar image matt1309 commented ·
Hi @mmx01


One to watch out for is you may technically need certificates given you're connected to the grid even if feed in is disabled (depend where you live). But i've heard of a lot of folk who risk it given it's difficult for anyone to even know you're connected without inspecting it.


Assuming you have no loads on "grid/ACIN side" that you want the inverter to cover then no need for a meter, the inverter has an internal CT clamp that should capture that data.

Tbf that is one other solution thought. You could wire high usage loads on ACIN side and have ET112 or another supported meter before them

ie grid -> meter -> highloads -> inverter -> normal loads.


If the inverter can it'll backfeed just enough power to cover the highloads in this setup. However this can be a messier setup given you'll need two distribution boards one for loads on ACIN side and one for loads on ACOUT side.


I believe virtual switch is not possible to use with ESS assistant enabled but again not 100% on that. Setting grid setpoint in ESS settings on gx device to 0 should accomplish what you're looking for.


ESS will prioritise battery/solar unless the state of charge of the battery drops below the minimum you set in ESS settings on the GX device.


MPPT will only ramp down output if grid feed in is disabled and batteries are at 100% ie power has no where to go (If you dont want export to grid in this scenario then you could even program an immersion/water heater to turn on if this point is reached using node red).


I agree it's a massive amount of functionality to wrap your head around. Up side of Victron system is if you can imagine a configuration it's probably supported but does mean it can be a lot of reading to understanding all the features.




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mmx01 avatar image
mmx01 answered ·

I have currently not so potent Growatt SPF3000TL. It is stated this is an off-grid inverter so technically it does not feed anything back to the grid and off-line installations do not need registration. Yet it packs an AC charger so it is connected in some way...


So it is very muddy if this is already grid connected or not. We can connect any AC charger to charge batteries without reporting it as long as it has CE and therefore won't disrupt the grid etc Being in Poland I see fascinating grid code discussion re. Victron as well. Someone over complicated few things I imagine but the time will tell.


Interesting if an isolation transformer physically separating the grid and the load (grid ->Victron AC in) puts this issue to bed altogether. 4kW units are not terribly expensive and this is galvanic separation so... nothing is connected at all.


I prefer to not have anything else on the AC IN side. Grid disconnect among anything else is a safety feature. Criminal charges carry some weight if something does not work there.


Will test either of options ESS setpoint 0 or virtual switch. I didn't find anything in the docs about it being disabled when ESS is on, but it does say not to use ESS when Ignore AC is to be used. Okay, but then what to use?


Hmm I'd love just a simple mechanism do not use grid until load is high or battery is low - say 20%, then use the grid when load exceeds inverter rating or battery is low.

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matt1309 avatar image matt1309 commented ·

It'll likely depend on your countries regs.

I think the theory that mechanism is ESS.

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mmx01 avatar image mmx01 matt1309 commented ·

As always they say you cannot connect energy source without cert and registration. Victron does have EU conformity cert and ESS grid code for EU. But there's debate this is not enough of course. My only option would be to use EU, PL resides within. I write from Belgium which is on the list and country of the inverter origin ;)


Then likely device block diagrams and classification will be key. I don't see how inverter behind an AC charger would be considered connected. It is not connected, the charger is connected and inverter is cascaded behind. That is easy with Growatt since it does not offer any flexibility and states off-grid on device plate. Even MultiPlus II without ESS is pretty clear but, ESS is a software feature.. so upon inspection where physically you have 0 export there's no way to concluding without extracting configuration for further analysis, that sounds already like court proceedings with experts involved. I am skeptic about regular field staff of any power distributor having tools/training to do so across variety of inverter vendors/types. But that's also "what-if".. I would definitely challenge "a default statement" as it comes across very subjective and likely come with 3rd party expertise to attest it being dependent on configured options.


I am rethinking one of larger loads to be on AC-in. But here I struggle with the back-feed nulling benefit. This is natural process for high load devices like microwaves etc. when they shut magnetron they anyway generate back-feed/feed-in to the grid regardless of any inverter. Just how the alternating stuff operates. However it gives a load on AC In to dissipate possible feed-in from the inverter. Seems a good idea after second thought to keep microwave as load on AC in with ESS setpoint to 10W.


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ejrossouw avatar image ejrossouw mmx01 commented ·
When you connect and synchronise your inverter (power generating) equipment with a grid and use ESS, rules and regs will apply given "feedin" is active, irrespective whether you sell excess back to the grid or not.
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mmx01 avatar image mmx01 ejrossouw commented ·
Right @ejrossouw , but with ESS disabled it basically is an off-grid setup with AC charger? AC in is then only used to charge batteries while inverter provides DC->AC conversion.
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ejrossouw avatar image ejrossouw mmx01 commented ·

@mmx01 Correct. You can either install assistants or ESS, not a combination. When using AC ignore, the relay remains open and all loads are powered via ACOUT unless an overload condition occurs and the inverter is stopped, relay closed and power is passed through to the loads. On the ESS, the ACIN relays are closed and the system synchronises / interacts with the grid. Not very obvious other than comparing the ACIN and ACOUT voltages on the two images. Even with a 0 grid setpoint and zero feedin, with ESS some very small amounts of power is fed into the grid, in particular when large loads drop off suddenly. 1706348258889.png

1706348465205.png

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1706348465205.png (27.7 KiB)
mmx01 avatar image mmx01 ejrossouw commented ·
That's very informative, thanks for taking the time to respond!


Small drawback I imagine is that in an overload condition I would not make use of either solar or battery power. However it will be sporadically I guess when all high power loads would be on at the same time as well.


I assume solar would still charge batteries while the loads run in pass through condition. My solar power is less than inverter rating so it is underpowered a bit and I don't think I would be losing too much due batteries likely not being 100% all the time hence having buffer to consume solar power anyway.


Will consider this as a starting point with less caveats than ESS.


M

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matt1309 avatar image matt1309 mmx01 commented ·
To be honest it may be worth just paying a local electrician just for a "consultation" just to pick their brains on how much of a headache getting certification for the install would be.


Might save yourself a lot of headaches if they say it's fine/easy. You could then just use ESS the way it was intended if that's the case.
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mmx01 avatar image mmx01 matt1309 commented ·

Well that's a bumpy road unfortunately, that's why I started off-grid even having grid on-premises and went with Growatt.

There is no more just declaration path.

  1. Submission needs to be made with complete diagram made by a person with paperwork or accepting to sign it.
  2. Same needs to be done for installing and attesting the installation.
  3. All parts of the solution need to be on the list and certified. Here we already know victron is not (yet). So either way it would be a no.
  4. I also have two 24/280Ah LifePo4 batteries done you've guessed it as DIY project, unlikely ever be certified not having any papers.

That's a hardcore process to be frank but our authorities in all silliness were going against green energy. Maybe it will change in the future but unlikely in months vs. years.


I read about non ESS options but I am a bit unclear how to avoid overload condition. Say pulling 5kW I'd like inverter to disconnect and pass-through AC-in when load is more than 4000W for 15 sec. Victron states 5500W for 2 minutes but then temperature, delays etc. Is it also done with just Ignore AC in?


"The grid is ignored when the AC loads are low. The grid is let in when the AC loads are high • This setting can be used to allow grid in when the AC load is higher than the Multi rating . This will prevent the Multi going into overload. This setting can also be used for large loads that you do not want to run from the battery."


This sounds right but I don't see mention of disconnection of the inverter. This is not ESS but virtual switch hence I assume it does disconnect the inverter.


I can pull 30A (fuse installed by the energy supplier) on each of 3 phases but this setup is single phase only.

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mmx01 avatar image mmx01 matt1309 commented ·

Hey, I got one more idea. Can I use 2x MultiPlus II in series instead of parallel?


One would be connected to the grid without ESS with AC In. The second would connect to the first one's AC 1 Out with ESS enabled. All loads would be wired to second one. Second one would provide loads of 3000VA alone and upon high demand ESS kicks-in supplying demand with the grid (in reality considering the first MPII as the grid).


Second MPII would have AC charger disabled to avoid charging batteries from 1st MPII inverter connected to the same battery bus.


First MPII would have virtual switch to Ignore AC grid under normal conditions SOC, load but would connect to the grid in case of overload or when batteries are low. Since this is not parallel operation I would set overload to 4000W for 30sec, then connect the grid.


With second working in ESS, this would only be true when second is consuming all of its rating and pulling up to +3000VA from the first assisting the loads (say 6000VA of power would be available before first one trips into overload connecting AC In?)


Solar would charge batteries and AC charger from the first MPII.


Crazy? Looks like it could work for my needs. ESS would not be connected to the grid being cascaded behind the unit that works off-grid...

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mjs500 avatar image
mjs500 answered ·

3kva x 0.8 = 2.4 Kw or 3000VA x 0.8 = 2.400 w

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mmx01 avatar image mmx01 commented ·

Don't quite get what this refers to? How this relates to grid rules or ESS (off-grid/on-grid)?


a) 2400 W =/= 2.4000 w, one zero and a dot too many

b) question was about going above inverter rating of 3000VA, which power assist with ESS provide altogether. So whether that would be cos fi 0.8 or 1.0, the question was about going above > 2400W or 3000W.

c) not to mention 0.8 is a faaaar stretched calculation where you seem to miss load characteristics... resistive loads like electric kettles, irons, water heaters, boilers have (cos fi) 1.0 so it is 3000W or 3kW for 3000VA




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ejrossouw avatar image ejrossouw mmx01 commented ·
ESS is NOT off-grid even if you don't feed excess in. Consider using no grid code with AC ignore then the ACIN will remain open and you can power loads from solar and batteries. Then set a condition to have it switch to grid when an "overload" occurs and power all loads from the grid (no inverting) and back when the overload has gone. PS - Powerassist should not be confused with the function that can support a weak shore supply with batteries. The inverter output rating plus the transfer switch rating is the total amount of power available to loads when using ESS.
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mmx01 avatar image mmx01 ejrossouw commented ·

Thanks. Can I also cascade two MPII one connected to the grid with ESS disabled, the other one connected to MPII AC 1 out (technically seeing MPII as a grid) with ESS enabled? I then could double the load of cascaded MPII providing for the loads.


Benefits, one could use two different versions of MPII, separate battery banks etc. since that's not a parallel system.


Looks to me this should be grid compliant as ESS is effectively operating behind another inverter.


https://community.victronenergy.com/questions/257362/total-ac-output-power-easysolar-ii-gx-243000.html?childToView=261520#comment-261520


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