Multiplus ii 24/3000 question about supplementing AC input.

[Burton4290]

Hey guys,

I have a Victron multiplus 24/3000 that is powering more than 75% of my house via a sub panel. I do have the multiplus AC tied, but use assistants to ignore the AC input based on battery SOC.

What i am looking to do however is to get the multiplus to "assist" the battery/solar from AC input only when it is needed. I know there is functionality (power assist) that works in the exact opposite way i am looking for. Power assist takes power from the batteries to assist large loads that the AC input cant handle.

I am looking for the AC input to only get tied in when i have large loads that the battery /solar cant handle. For example, my AC load is 3000 watts. I plug in a vacuum and the AC load jumps to 4000 watts. I want the 3000 watts to come from battery/solar, and then have the AC input ONLY make up the difference of 1000 watts.

Ive been plsying around with the settings for hours, and i have gotten the AC input to function based on AC load, but when the AC input is turned on it powers ALL of the AC loads and completely shuts off the battery/ solar.

Thoughts?

 

[sunshine_eggo]

Hey guys,

I have a Victron multiplus 24/3000 that is powering more than 75% of my house via a sub panel. I do have the multiplus AC tied, but use assistants to ignore the AC input based on battery SOC.

"AC tied" implies grid interaction. You likely mean you are using grid as backup.

What i am looking to do however is to get the multiplus to "assist" the battery/solar from AC input only when it is needed. I know there is functionality (power assist) that works in the exact opposite way i am looking for. Power assist takes power from the batteries to assist large loads that the AC input cant handle.

I am looking for the AC input to only get tied in when i have large loads that the battery /solar cant handle. For example, my AC load is 3000 watts. I plug in a vacuum and the AC load jumps to 4000 watts. I want the 3000 watts to come from battery/solar, and then have the AC input ONLY make up the difference of 1000 watts.

What you want is essentially impossible without grid interaction.

PowerAssist is a nearly unique one-way feature that works only when AC can't support the load.

The only way you could sorta make this work is if you set your AC input limit low enough that a big load is likely to engage PowerAssist and force the inverter to boost the AC input.

When AC input is not ignored, the AC input it is the "master" source, i.e., the inverter is forced to "sync" to that voltage and frequency and "piggy back" itself to it matching it perfectly. It's not as challenging to sync with the active source and boost it as it is to STOP inverting (where it completely looses the ability to measure or power the load), switch to AC input, sync to it, boost to peak output without overshooting, and then determine what AC input limit it needs to observed to operate as you desire.

While ESS is not typically used for non grid-interactive systems (never for grid-interactive in the U.S.), you might be able to find a way that makes it work for you. Good luck.

ESS design and installation manual

www.victronenergy.com

 

[Burton4290]

"AC tied" implies grid interaction. You likely mean you are using grid as backup.



What you want is essentially impossible without grid interaction.

PowerAssist is a nearly unique one-way feature that works only when AC can't support the load.

The only way you could sorta make this work is if you set your AC input limit low enough that a big load is likely to engage PowerAssist and force the inverter to boost the AC input.

When AC input is not ignored, the AC input it is the "master" source, i.e., the inverter is forced to "sync" to that voltage and frequency and "piggy back" itself to it matching it perfectly. It's not as challenging to sync with the active source and boost it as it is to STOP inverting (where it completely looses the ability to measure or power the load), switch to AC input, sync to it, boost to peak output without overshooting, and then determine what AC input limit it needs to observed to operate as you desire.

While ESS is not typically used for non grid-interactive systems (never for grid-interactive in the U.S.), you might be able to find a way that makes it work for you. Good luck.

ESS design and installation manual

www.victronenergy.com

Great advice, thank you. Im glad to hear my thinking was going in the right direction. I spent the night playing with the AC input limit and power assist. Ive got it to where i can run a 4000 watt load with 1000 from the grid and 3000 from the batterys/solar with power assist.

Sounds like this is the best im going to do. Which is fine by me. Thanks again.

 

[Checkthisout]

Great advice, thank you. Im glad to hear my thinking was going in the right direction. I spent the night playing with the AC input limit and power assist. Ive got it to where i can run a 4000 watt load with 1000 from the grid and 3000 from the batterys/solar with power assist.

Sounds like this is the best im going to do. Which is fine by me. Thanks again.

They added a new feature called "prioritize other energy sources" that I believe lets you do exactly what you want you're looking to do.

 

[sunshine_eggo]

"Prioritize other sources" only impacts battery charging. If AC input is not ignored, it still passes AC through to loads.

Solar and wind priority [Victron Energy]

www.victronenergy.com

• For charging the battery, as well as powering DC loads, solar and wind are prioritised. For AC loads that is not the case, shore power will be used to power them. Which in many systems is not really an issue, since they are small - or the available and solar and wind won't be sufficient. In case you do prefer to also power AC loads from the battery, solar and wind - then look into our Ignore AC input options, in VictronConnect available as the “Conditional AC input connection” settings menu. Also described in detail on this blogpost on Panbo.com