question

petajoule avatar image

HowTo PV Charger priority over Quattro Charger

A non-ESS hybrid connected to the grid with Quattro mode "on" will throttle down the PV charger and charge the battery from grid...

grid-quattro-prio.png

when, by putting the Quattros into "inverter only" mode, the PV charger could actually deliver the charge. Or at least any charge so it would not be needed from grid:

pv-charger-prio.png

Obviously, the question is how to achieve PV charger priority over Quattro charger priority, so one could leave the grid on, but not at the expense of PV chargers being turned down, which IMHO should have been the default in the limbic (non-assistant) system of Victron devices anyway.


battery chargingmppt chargingdc systemnot charging
grid-quattro-prio.png (131.2 KiB)
pv-charger-prio.png (103.2 KiB)
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2 Answers
Rob Fijn avatar image
Rob Fijn answered ·

Hello Petajoule, for your one year test you can use the Virtual Switch in the Quattro to ignore the grid and use this only when the SOC is below a set level (for example). You can even use the Generator Relay for this to simulate your generator, use the Relay to switch the Grid ON or OFF with a big relay. If you have internet you can make a email trigger to warn you when this happens. I guess you want to learn if you can run your system completely off-grid.

I hope this helps you further.

Regards, Rob

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We're doing something similar already with our PLC-like script on a GX device https://github.com/petajoulecorp/vicgx_plc with this, we can turn the Quattros from "inverter only" to "on" and back (depending on e.g. SoC). Without the need to go via some external big relay or similar.

However, this doesn't address the problem.

We would like to achieve that even in the case grid/generator is on, all available PV charger power - up to the demand by system (AC-OUT and Battery charging) - is used with preference. Currently it is the PV charger who is throttled down to 0 and generator/grid delivers "everything".

In said off-grid system with no grid connection but only generator, this means that the PV charger should run with max capacity and not be throttled down because the generator is delivering "enough".

Generator power is expensive and loud and stinky, PV charger power is cheaper, silent and clean. So we wonder why the priority is not vice versa in such a configuration by default.


Hello Petajoule, understand what you mean. The way to do this is to set the charge voltage different. As there are actually two charges in parallel: The Quattro and the MPPT. The MPPT charge voltage should be then 0.1 or 0.2 volt higher then the Quattro. I guess you need to play and test this.

Let us know how this goes.

regards, Rob

Riaan Barkhuizen avatar image
Riaan Barkhuizen answered ·

Hi @PetaJoule


Why are you not using the ESS assitant? Is there any reason for that? In my experience the ESS will do exactly what you want to do on the site by giving priority to solar charging over grid charging in addition it will also unlock more settings for you to further fine tune operation of the system.


Best Regards

Riaan

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The reason mainly being that this is an off-grid installation in the transition phase. I.e. checking reliability for 1-year operation before disabling grid entirely and adding a fixed genset installation.

Victron themself say that ESS is not to be used in off-grid systems. So if one abstracts from "grid" - which in this case has LOM disabled and just emulates the genset, we have an off-grid system that is actually not using the PV generators but gives more priority to the AC-IN generator (whatever that may be).

I would like to believe it is possible to design an off-grid system with Victron components to do this without ESS.

Why using a PV inverter (AC coupled), then?