I’m running an ESS setup at home based on a MultiPlus and optimizing it via Node-RED.
By default, the system prioritizes: 1. Solar → consumption, 2. Solar → battery, 3. Solar → grid
I’d like to change this priority to export surplus solar to the grid before charging the battery. Essentially, to delay battery charging until hours with low or negative electricity prices.
I’m comfortable implementing the logic in Node-RED, but I’d like to ask:
Is there a direct setting or supported way to disable battery charging or reverse this priority?
What’s the most efficient method to achieve this behavior?
So far, I’ve only found dynamically adjusting the Grid Set-point but that doesn’t seem ideal for this case.
Any guidance or best practices would be much appreciated.
Unless I’m mistaken there’s no direct way to change the priority because, up until dynamic prices and DESS came around, this was the best and only strategy that made sense.
What you’re trying to do is not new, others have been tinkering with the same thing.
You might want to update your post to mention that you’re running DESS and not regular ESS.
Possible ways to implement what you’re trying to do:
tinker with the grid setpoint, but if I’m not mistaken negative grid setpoints and DESS don’t mix very well in the current stage
tinker with the DVCC charge voltage limit
(Charge current limit is an alternative that looks like a logical option, but apparently voltage limit is more efficient. After all, charge current is an effect of voltage)
override the DESS schedules
create your own (D)ESS charge/discharge logic (this is what the big boys are doing)
Maybe other options exist as well.
The DESS schedule option will by far be the cleanest but more tricky to implement, all other options are pretty much hacks that will disturb the current DESS logic.
Ultimately the DESS algorithm will (need to) be updated (by Victron) to take this behaviour in account, but last I’ve heard we’re not there yet.
But it’s being worked on.
Thank you very much for reply.
I’m actually using regular ESS (not DESS), as I have a fixed import price and spot-based export price tariff.
I do a bit of automation via Node-RED. Mainly toggling basic settings (SoC, Grid feed-in, Grid set-point) based on price, yield prediction etc, but I’m not overriding the full control logic.
I’m reluctant to touch DVCC charge voltage limit I’m not fully confident in the implications.
That’s why I was hoping for a direct and supported setting to temporarily disable battery charging (something like the /Hub4/DisableCharge = 1 in example), while still allowing feed-in to the grid.
The victron system does not want charging disabled, it is also why they don’t want CCL set to 0.
If you want to stop the battery charging, the best way is to manipulate the charge voltage. Voltage is always the best way to control charging.
That should still work with DESS. Just set the fixed price for import and the spot formula for export.
That way, if you have supported PV inverters that support power throttling, DESS will throttle them down when injection price is negative.
To export (from battery) to grid at the best possible price might be possible with DESS but I have no idea how advanced the algorithm to do that already is.
To do that with plain ESS and some custom Node Red glue shouldn’t be too difficult.
You could set the Gridpoint to the negative value of the PV output power during the hours you prefer. With regular ESS that’s the simplest way.
When running an ESS system with AC PV inverters on AC Out, you want to have battery charging enabled.
Let’s say the sun is up and you’re injecting surplus to the grid.
Then your grid suddenly goes out.
You need to dump the excess PV power somewhere or risk blowing everything up.
So you dump it in the batteries, and to do that you need to have charging enabled.
Yes, also if batteries are at 100% they can still take a short jolt of charge.
That’s why there’s a minimum battery capacity rule.