Victron ESS and Virtual Switch MPPT Charger Function

[ninomartinez]

Hello Everyone:

I've got a pair of Multiplus ii (UL) configured for a 240v split phase System (250/100 MPPT, Cerbo S and Lynx Distributor) for which I opted to install the ESS Assistant along with a flag and a couple of relays to control the AC input. The AC input is currently set to kick in at around the 28% SOC and starts powering the loads at 20% SOC (or whichever minimum SOC is selected on the Remote Console), it will revert back to being ignored @ 33% SOC (by then, the inverter will be powering again all of the loads purely from DC source).
So far, it's been a rock solid setup that has reduced my daily consumption to the 0-2kwh mark from the grid depending of how good of a charge I get the day before but it got me thinking, how does the Victron MPPT Charger behave in a setting such as a Virtual Switch programed to ignore the AC input. Does it still operate like a constant DC Power Supply by communicating with the inverter or is it more in line with the normal bulk, absorption and float stages of the charge?
Thanks for your insight in advance.

Regards

Nino

 

[sunshine_eggo]

Hello Everyone:

I've got a pair of Multiplus ii (UL) configured for a 240v split phase System (250/100 MPPT, Cerbo S and Lynx Distributor) for which I opted to install the ESS Assistant along with a flag and a couple of relays to control the AC input. The AC input is currently set to kick in at around the 28% SOC and starts powering the loads at 20% SOC (or whichever minimum SOC is selected on the Remote Console), it will revert back to being ignored @ 33% SOC (by then, the inverter will be powering again all of the loads purely from DC source).
So far, it's been a rock solid setup that has reduced my daily consumption to the 0-2kwh mark from the grid depending of how good of a charge I get the day before but it got me thinking, how does the Victron MPPT Charger behave in a setting such as a Virtual Switch programed to ignore the AC input. Does it still operate like a constant DC Power Supply by communicating with the inverter or is it more in line with the normal bulk, absorption and float stages of the charge?
Thanks for your insight in advance.

Regards

Nino

ESS is only for use on grid-tie system with an interconnect agreement in countries where it has a valid grid code. Even if you have CT sensors to prevent backfeeding, you will still backfeed.

You can't use ESS and Virtual Switch at the same time. You use Virtual Switch OR you use assistants. You don't get both.

If you don't want to backfeed to the grid, you don't want to use ESS. There are multiple other ways to manage how the MP treats the AC input.

The MPPT is simply a charger. It takes PV and outputs a voltage/current to the battery. ESS and some Cerbo settings can influence MPPT behavior, but that's typically only the case when you want to instruct the MPPT to continue maximum output even though your battery is full for the purposes of backfeeding to the grid.

 

[ninomartinez]

Thanks for your input sunshine:
I'm well aware that the ESS is incompatible with the Virtual Switch, definitely not interested in feeding back to the grid. I originally gravitated towards this assistant since the ESS literature points out that it keeps the charger "working hard" to not only charge the batteries, but to also supply the loads simultaneously.
That's the part that I'm really interested in learning about, if I should opt to disable the ESS and relays that I currently have in favor of a more simple solution like a Virtual Switch and still have the added benefit of keeping the charger working all day while the sun is up.
In regards to feeding back to the grid, for the most part I've kept it in check by turning on and off the relays so that the grid is available mostly during the time that the batteries are supplying the loads in order to avoid any "overshoot" from the mppt and with a 40 watt grid setpoint. The most that I've back fed at any given point has been around .1kwh, that's why I started using the relays to remove the grid from the equation altogether.

 

[sunshine_eggo]

Thanks for your input sunshine:
I'm well aware that the ESS is incompatible with the Virtual Switch, definitely not interested in feeding back to the grid. I originally gravitated towards this assistant since the ESS literature points out that it keeps the charger "working hard" to not only charge the batteries, but to also supply the loads simultaneously.

This is default off-grid behavior.

That's the part that I'm really interested in learning about, if I should opt to disable the ESS and relays that I currently have in favor of a more simple solution like a Virtual Switch and still have the added benefit of keeping the charger working all day while the sun is up.

VS is somewhat limited, but can do a decent job.

If you're just looking to manage when you draw from the grid, the Cerbo Gen autostart/stop feature is the preferred method. Simple and feature rich:

In regards to feeding back to the grid, for the most part I've kept it in check by turning on and off the relays so that the grid is available mostly during the time that the batteries are supplying the loads in order to avoid any "overshoot" from the mppt and with a 40 watt grid setpoint. The most that I've back fed at any given point has been around .1kwh, that's why I started using the relays to remove the grid from the equation altogether.

I'm sure it won't be a problem until it is.

Here in the States, even slight and intermittent backfeeding will get a knock on your door from the power company and may carry legal penalties depending on state/county/local law.

 

[ninomartinez]

Thank you very much for the insight, if that’s default behavior I would rather not risk the possibility of any grid feedback whatsoever. Going to tinker with the Virtual Switch first but the generator options with the Cerbo are pretty comprehensive from what I can tell on that video.
Again, thanks a lot for your input!

 

[sunshine_eggo]

Thank you very much for the insight, if that’s default behavior I would rather not risk the possibility of any grid feedback whatsoever. Going to tinker with the Virtual Switch first but the generator options with the Cerbo are pretty comprehensive from what I can tell on that video.
Again, thanks a lot for your input!

Having used VS, assistants and Cerbo, Cerbo method is the best by far.

On your touch screen, or on the VRM inverter control window, you'll be able to manually override the "ignore ac input" to force charge or to force ignore AC input.

 

[ninomartinez]

You bring an important point, I only want the batteries to be charged from the PV array, I have the inverter charger disabled as we speak. Only interested in turning on the AC to run the loads while the SOC goes back up to 30%. I believe the charge option from the inverters would be through the Victron Config software right?

 

[sunshine_eggo]

You can use the prioritize solar/wind option on the advanced tab in VEConfig. You can set a voltage there above which the charger is disabled.

Can can also simply disable the charger or set it to a low current on the charger tab.