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Hi
After some information as to how the above components will react together in a ac coupled off grid system?
I understand frequency shifting will restrict the pv from the Fronius
How does this perform or react if there is a generator running for supplementary battery charging ?
Regards mike
Victron provides some pretty extensive background information on power systems using our equipment, from the very broad Energy Unlimited, and Wiring Unlimited to the very specific on AC Coupling, and Fronius.
Large off grid system design and installation incorporating AC solar, generators and inverter chargers is a considerable undertaking, often costing $10,000's of dollars in equipment, many hours of design and installation time, and potentially life threatening voltages.
Victron offers training programs in design, equipment selection, support, and technical troubleshooting to our world-wide dealer network.
It is STRONGLY RECOMMENDED that you contact one of these near to you to discuss your options in more depth than I am comfortable doing here with limited information.
In a correctly designed and configured system, the CCGX and Quattro will regulate the charge that is required by the loads and the BYD batteries. It will signal to the AC PV inverter via frequency when it should generate, and when it should ramp down.
A correctly configured Quattro is able to control the demand on the generator directly, either loading it to charge batteries, allowing it to run loads, letting it idle if batteries are full and loads are supplied by solar PV or disconnecting it if necessary.
If you are worried about the surplus AC PV potentially back feeding into the Generator, it is possible. In this case it can be an option to modify the configuration of generator on AC2 input and AC PV inverter on AC2 output of the Quattro and program them via assistants to only be available during states of charge or voltage ranges where there is no chance of reaching full charge simultaneously while both are connected, or it must only be one or the other connected at all.
Again, I would like to be more helpful, but may end up doing more harm and must emphasise that these kinds of issues and advanced configurations are best managed by in-person comprehensive training and an experienced installer, not via this community page.
Ive actually got a very similar install at the moment. I have two parralell 15kW quattro inverters, two fronius primo 8.2kW AC inverters, and 4 BYD b-BOX pro battery banks . I have a colour control installed, the site has a high energy demand so I have added a Stephill 20kVa backup generator that i anticipate will run a few hours a day at least through the winter months. So even though communication is possible between the fronius inverters and the colour control theres still a chance of backfeeding the generator. Can you tell me what assistants should be loaded onto the quattros, and if as said above that its possible to stop this by using AC in 2 and AC out 2 would it be best to install one 8.2 kW primo on each quttro AC out 2 output. I found on another thread that it probably wouldnt be a problem but being that the generator was almot £10,000 I would rather there be no chance of a problem. Thanks Jack
Hi @jacko,
As I tried to also articulate in my other answer, this is not design that Victron intends to be answered here on the community. At least not by us, if another installer has experience and wants to document it here, that would be interesting to hear from them.
Please contact your distributor or Victron Sales Manager for support or training with this level of programming.
The most relevant documentation around this is here:
https://www.victronenergy.com/live/assistants:ignore_ac_input_using_the_generator_assistant
You can program the necessary combinations of assistants in VEConfigure, the exact settings to use will depend on your installation.
Thanks for your reply Guy, yeah I understand why, I think ive worked out the assistants needed to disconnect them while the genreator is running. I cant really see it being an issue even if the batteries where low so the generator was running and a cold sunny patch of wether came over making solar generation go near maximum outout that would surly be used to fill the batteries and generator would ramp down its output to whatever extra i had allowed as the maximum charge current, i will only have the genereator topping up from 20-50% aswell so there will be no scenario where they would need frequency controlling while connected to the generator. If any other installers want to comment that would be great. Thanks
That sounds like you understand the situation.
Another possible scenario to be careful of is when very large loads are running and then suddenly stop, and they are provided for by both the generator and the AC solar.
Thanks Guy, can you say what size of load you would consider big enough to cause that type of issue, i would say 5kW is the biggest load that would drop out at one time on this site. Thanks Jack
It's ALL relative. Size of battery, to size of inverters, to size of solar array, to size of sudden load.
I don't have a rule of thumb, But I can make something up that sounds about right to me.
Lead is actually a lot more tolerant of a voltage spike at the top end of it's charge cycle than lithium is. But lithium is a lot more absorbent than lead is midway through.
I would guess at the limit is around whichever is the smallest of - the load is within 50% of normal maximum operating current (eg 50% of C10 for lead, 50% 1C for lithium), and 50% of the inverters rated capacity.
But bad timing can cause an issue anyway, normal heavy load turns off, along with a normal but unexpected load right when the sun comes behind the cloud and power output shoots through the roof on a full battery.
[quote]Lead is actually a lot more tolerant of a voltage spike at the top end of it's charge cycle than lithium is. But lithium is a lot more absorbent than lead is midway through. [/quote]
this only applies to LiFePO4 lithium batteries, Li-ion batteries can absorb maximum current till 100% charged voltage.
Thats all good to know, so with a 40kWh lifepo4 battery bank that will be at most half charged with the generator running should be able to take the spike of a 5kW load dropping out. Ive added a 4 pole NC contactor with a 230v coil in line with the two primos, with the coil energised by the output of the generator so if i do experiance any problems i can switch this in. Thanks for your help
Hi
In relation to the original question will be using a 2nc 2 no contractor on my installation the 2 normally closed will be the fronuis pv inverter and then 2 no generator when the colour gx calls for the generator the contractor will disconnect the fronuis inverter and connect the generator so there will be no running Generator and pv inverter in parrellel mo possible back feeds either way.
Set up will be 3.5kw of solar 3.6 fronuis primo
2 x multi plus in parrellel and 6 byd 2.56kw b box pro
Hi Mike
Is this working well for you still? Just about to endeavour on a similar set up and came across this post. What happens to the Fronius while disconnected? does it go to sleep or is there an option not to so its ready when reconnected?
I happen to have a Skylla charger, so was musing on the idea of having this run from the disconnected Fronius to maintain some benefit from the PV while the genny is necessary.
Nigel
set-up: 3 x 10kVa Quattro in 3ph, 45kVa 3ph genny, 4.8kWp on DC, 600Ah battery. The expanded system will add 10kWp on AC and add 1000Ah battery. (3 off grid houses)
Hi
Thanks for the question
The system I have up and running
Is 2 48v 5kva multi’s in parallel with 6 2.56byd units
And a fronuis 3.6 primo coupled of the pit put side of the multi’s
It’s working really well
After a conversation with fronuis they have said the fronuis is ok still being active on the output side of the multi when the generator is running
And have had no issues
If there is anymore you would like to know please feel free to ask
Regards
Mike
Thanks Mike
Can I just clarify the Fronius is on the AC-out, and that it is set to reverse charge the batteries when there is surplus generation? What assistants are you using to keep the Multi from back feeding the genny?
Also, what are you using for communication? My Fronius will be 200m away from the power shed so I'm looking at a RS-485 connection.
Ta
nigel
