Please confirm that I am correct regarding the following: If an ET112 is installed just
after the main circuit breaker, the energy used will be measured from that point and not
from the output side of the Multi, and therefore any excess PV energy, after the loads
on the output side of the Multi is covered and the batteries are charged, will be used to
power the loads on the AC-in side as well. Basically, it is “grid feed-in”, as it feeds back
through the Multi, but only to that point (the ET112) and not the grid itself.
If so, am I also correct that the batteries will never be used to power those loads, as
only excess PV power is fed in, and not stored battery energy.
Lastly, if the above is correct, do I need to enable “DC-coupled PV - feed-in excess” in
ESS, and not limit the feed-in for this to work?
The grid set point that you set in your ESS is what the Multiplus is aiming to reach. When you add a ET112 reader you move the position where this measurement is done from the Multiplus to where that reader is installed, and so the Multi will try to power your setup so that the grid set point you set up is at that value at the position of your meter. And then the Multi will push power back on the input side to reach that.
It works the same as having all that on the non backup AC-Out2, except you need less wires installed.
You don’t need to set any DC-coupled PV or feed-in. Those settings stay as they are, cause only your measurement point moves to the meter.
About if only the PV is to be used and not the battery, I think they will both be used, but only while the grid is connected. When loadshedding happens that meter does not have power and the grid point measurement moves back to your multi and it will not puch power back to the input.
No… input side. The Multi tries to keep its input at zero (or whatever you set as the setpoint), and it will charge or discharge the battery in order to keep it that way, until the battery is either too low (MinSoc) or it is full. But close enough…
Not only excess. It will use battery energy as well. The philosophy is that it tries to keep your grid import as low as possible for as long as possible.
The ET112 merely moves the measurement point. The system makes no distinction between input/output side loads when it decides how to minimize your bill. The distinction only matters when the grid fails… then only the output is backed up.
I know there are people with use cases where they want power to be fed back to the input, from the battery too, but not always… the use case is specific, and best implemented with something like node-red. For now anyway. It is now part of the Venus 2.90 large image release.
Any way to get around this, as I don’t want these loads to use energy from the batteries at all, but wouldn’t mind if excess PV can contribute. We have 2 x solar geysers, oven and bedroom aircon running from a separate DB before the Multi; so they do not get the benefit of any PV power, which is fine since we use them 99% of the time at night. However, it would be nice if excess PV power can help a little when the oven is used on say, a Sunday at midday, or if we can heat up the geysers in winter during midday - but I really don’t want to use any energy from the batteries for this, e.g. if the aircon is used in summer at night, the batteries will reach their minimum SOC in no time, same with the oven. We use scheduled charging between 5 and 8 at night, when all the other energy unfriendly appliances are used (air fryer, kettle, microwave, etc.) and that works fine, so maybe that will be a solution?
There is no way to change that, except if you go make custom rules and fiddle in things like NodeRed or Home assitant.
You can only play with the Min SOC% value. That is the input variable for if battery is used or not in ESS mode on a Victron System.
I think you can achieve what you want within the Venus OS.
Have a good play with it.
I found scheduled charging quite flexible for achieving a desired daily basic usage pattern.
Quirky stuff, then yes Node-Red is the go-to.
