I am trying to control the Grid setpoint on a Cerbo GX / Venus OS v3.72 while keeping the system in ESS mode 1. My goal is to update the setpoint dynamically from Node-RED every minute, but I want to avoid writing repeatedly to com.victronenergy.settings /Settings/CGwacs/AcPowerSetPoint because this is persistent storage and I do not want unnecessary flash/eMMC wear on the Cerbo. I tested /Hub4/L1/AcPowerSetpoint, but in my system that only seems relevant for ESS mode 3 / external control, not for mode 1.
So my question is: Is there any supported non-persistent / in-memory way to set Grid setpoint while remaining in ESS mode 1?
No… Make a try and you will see that when you use this node to set the grid set-point, then it becomes the new value even if you reboot Cerbo GX. This clearly tell us that it is saving this into the SD. So, if you write on it every minute it will just wear Cerbo’s SD. I am not sure if doing this is a problem or not but many configurations run from RAM not to destroy the SD.
No and sort of yes.
No because DESS mode 1 (auto) adjusts the grid setpoint every 5 seconds with the goal to reach the TargetSoC of the current (15 minute) window, at the end of this window.
Yes because you can adjust that TargetSoC (of the currently active and the future schedule windows upto 12 hours in advance) to such a value that that will result in the grid setpoint you want (until VRM DESS pushes an updated schedule, then you need to set these TargetSoc values again).
If you do not really need to stay in mode 1, I’d try setting disabling DESS and go manual, otherwise, it can be done but it is not trivial.
I am not running DESS; I am running ESS in mode 1. ESS provides a lot of background functionality, so I do not want to bypass or replace it.
I am supplying power, via the grid, to a remote house. That remote house is billed by its regular utility based on the 15-minute energy balance. When I inject power into the grid, the remote house can offset part or all of its consumption from its normal supplier.
I measure the remote house consumption every minute, then inject power into the grid to compensate for that last-minute consumption, with the goal of reducing the remote house net consumption from the utility to zero. In practice, this means I need to update the grid set-point every minute based on the remote house consumption during the previous minute.
Given this, my goal is to keep ESS enabled, to simplify overall system management, and only change the grid set-point dynamically, but in RAM rather than through persistent settings, so as to avoid wearing out the Cerbo’s SD/eMMC.
I got no SD card on the Cerbo. I don’t know what Victron use as a disk but I know it must be some form of onboard SD/Flash, etc.
What I know, from this forum, is that you should prevent from aggressively write on persistent configuration as it will decrease the Cerbo’s disk life time.
