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duswami avatar image
duswami asked

Which Relay assistant for Conditional AC, DV switching

I want to program some relays in the Multi II for conditional AC, DC usage instances and am confused as to which assistant/relay I should use, the programmable relays, general Flags or AC-related relays. The conditions I'm trying to set are as follows:

  • If MAIN AC and SOC is greater than 98% and PV is greater than 100W then use PV for loads, when not enough PV use Bats to 75% SOC
  • If MAIN AC and BAT SOC less 75% PV Charges bats to 100% SOC and use 100% Grid for loads
  • If Main AC and PV is less than 100W then charge bats
  • If Main AC and no PV use Grid
  • If no Main AC and SOC is greater than 98% and PV is greater than 500W then use PV, when not enough PV use Bats to SOC 55%
  • If no Main AC and Bat SOC is less than 55% use PV to charge to 100% SOC, don’t use Bats for loads
  • If no Main AC and PV less than 500W charge batters to 100% SOC
  • If no Main AC and no PV Run loads on Bats to SOC 55%

* Note: in the instance of no MAIN AC, AC OUT 1 is the only source of AC to essential loads.

For PV conditions, should I use W or VDC? I'm more interested in utilizing the PV when requisite Watts are available as the system generates between 85-75 VDC between sunrise and sunset.

If anyone could kindly take me through an example routine step-by-step, or screenshot their own so I have a model to work off of I would appreciate it! Any tips, suggestions or helpful hints would be great too. Or, if there is an easier way or a better method to condense these to achieve the same result feel free to let me know. Not using ESS btw. Thanks! :)


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2 Answers
Alexandra avatar image
Alexandra answered ·

@Duswami

You will really only be able to ise SOC and load based controls on the AC conditions to connect or disconnect.

Victron connect have a demo library you can play with for that.

Or you can run through a few articles like this one using the generator function on the GX.

https://www.victronenergy.com/live/drafts:acin_ignore_timer_using_ccgx_gen_start_stop_example

Or this one on the inverter itself

https://www.victronenergy.com/live/assistants:ignore_ac_input_using_the_generator_assistant

Your other options are using contactors and relays for commands but is more complex to set up.

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duswami avatar image duswami commented ·
Yeah I did some more reading on this. It's confusing between using the virtual switch and setting up the relays. It seems like it's an either or option correct?

My focus is just on prioritizing PV over battery depending on SOC. Aside from the additional complexity is that not possible, or is that something you need to go to Node Red for?

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Alexandra avatar image Alexandra ♦ duswami commented ·

No. There is more what is convinient and easy for you to set up. And based on what you need.

Conditional AC in Victron Connect is basically Virtual switch in VE Config.

Most people who use the assistant for generator to ignore AC do so because they have other assistants they need/want to use so have to disable Virtual Switch to do so, but still want the function.

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duswami avatar image duswami Alexandra ♦ commented ·
@Alexandra I see. I was looking at the generator assistant in the Cerbo, is that not the best solution. Incidentally, where is that conditional AC toggle, I can't seem to locate it?
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Alexandra avatar image Alexandra ♦ duswami commented ·

@Duswami

AC input control in Victron Connect? The manual describes all the settings.

screenshot-20220620-072415.jpg

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duswami avatar image duswami Alexandra ♦ commented ·
Ah yes, got it thanks
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duswami avatar image duswami Alexandra ♦ commented ·
@Alexandra So, looking at this, is this duplicative of the VS?

And, can I use the Generator assistant to achieve my goals with a DC Coupled system?

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Alexandra avatar image Alexandra ♦ duswami commented ·
@Duswami

Yes ac ignore in ve config is vitrual switch.

Ess will work on grid code other (it is the one I use for most of my installations.

Just tighten the voltage cut offs a bit and make sure you aren't feeding back (if it is not allowed)

The ess manual is here.

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Alexandra avatar image Alexandra ♦ Alexandra ♦ commented ·
And the generator assistant will acheive the same idea.
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duswami avatar image duswami Alexandra ♦ commented ·
@Alexandra thank you.. is there any good resources for configuring grid 'other' for a US installation or is that not pertinent as I'm probably setting my Grid setpoint at 50-100w and focusing on voltage cutoff as you mentioned. I have an EM24 AVI6, should I utilize it? Thanks for your continued help @Alexandra
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Alexandra avatar image Alexandra ♦ duswami commented ·
@Duswami

Not to my knowledge. Usually it is best to talk to local distributors. As more often that not there are regulations that need attention.

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duswami avatar image duswami Alexandra ♦ commented ·

@Alexandra Sorry, voted your comment down, not intended, bad eyes, lol. Talked to my local distributor, he was unable to help with ESS as he doesn't/hasn't used it. As for voltage cut-off, are you referring to the discharge current, if so, what range is acceptable. LOM Type B seems most applicable. I do have a generator wired directly into the service panel (not through the Multi/relay) I will set my grid point at 75W, its a smallish system, 1.4kw. Concur?

screenshot-2022-06-22-164834.jpg

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Alexandra avatar image Alexandra ♦ duswami commented ·

@Duswami

That is a good start.

Run the system and see how things go for you.


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duswami avatar image duswami Alexandra ♦ commented ·
@Alexandra Got it all up and running, so far so good. Implemented a few concepts.

Using 'Optimized" with battery life, but using the DVCC trick setting SOC to 100% to mimic Keep Batteries Charged but avoiding the known issue with MPPT Charging.

Using Scheduled charges to keep the bats from discharging during during non PV producing hours.

One issue I'm trying to understand is the Max Charge current in DVCC, since I have a smartshunt measuring DC Loads, can I leave the Max current at 50? And for Max Charge Volts, am I using the Absorption voltage or the equalization voltage?

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Alexandra avatar image Alexandra ♦ duswami commented ·
@Duswami

What batteries do you have?

Max charge voltage is fine. And max amps is what you want your bank to be charged with system wide combined. So if it is 50. Then set 50.

It wont limit your pv production for loads in any way.

Is the system been set up as has DC loads?

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shaneyake avatar image
shaneyake answered ·

Can you explain why you don't want to use ESS? It is normally the best option for cases where you need to use PV.

If you have a Cerbo GX I would use the Large firmware
https://www.victronenergy.com/live/venus-os:large
You can then use NodeRed to fully control your system.
Will need a wire from GX relay to AUX input if you want to control AC OUT2.

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duswami avatar image duswami commented ·
@shaneyake Well, technically, I could use ESS, my grid is United States, so I'd have to manually configure with no grid code. Havent found a good thread or guidelines for configuring in the US since it's not supported in ve config. I'm interested in Node Red, but I've been told it's difficult to work with if you don't have programming background.
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