here my annotations:
- System: assuming 3-phase 25A fused: set maximum import and export power both to 17.25 kW. Set to Trade mode.
- Battery: capacity set to actual useable dayly cycleable capacity, 48kWh is that is the case
- Maximum discharge power: set a little higher than the MP II’s combined maximum inverter power, so 3 x 5 = 15kW
- Maximum charge power: set a little higher than the MP II’s combined maximum charge power, so 3 x 70A * 52.8V ~ 11 kW
- cycle life: (just for easy of calculation: price €4800, cycle life 1000 cycles (i’ll explain another time) should give €0.10 €/kWh
- Battery balancing off (well , to be controlled by the PFCO flow later)
- No other restrictions (for now)
- Buy prices and sell prices same settings, the difference is now taken into account with the cycle costs (real or imagined). Tibber does (p+0.0205+0.10154)*1.21 flat rate, also negative, zonneplan I don’t know for sure but I don’t expect negative prices during this test so just set to the same (p+0.01653+0.1088)*1.21 or do check here in the forum for an update on the actuals
- Cerbo minimum SoC 10%
- Grid setpoint 0W (no use if you do not need to ‘hard’ prevent feed-in
- No other limitations, no peak shaving, no scheduled charge levels (won’t work anuway, this is why I use the Node-RED DESS b_goal_SOC and b_goal_hour instead.
- AC-coupled PV feed-in excess: That I do not know yet , lets try without that setting for starters
- ESS Dynamic ESS, looks confusing that target SoC reads 0% but is very likely that the system is in ‘1 - self consumoption’ at the time you took the screenshot
- Charge control DVCC: I have no experience with that, if your batteries are well protected by their (JK?) BMS AND if you could add a BMV 712 Smartmonitor instead of using the BMS data, I would very very strongly advise to do so. JK SoC calculations are horrible while the BMV 712 is near perfect. And with 48kWh total capacity, ~ 938Ah you should be able to to at very least 0.2C is 188A and 0.5C is 469A, depending on the combined limits of the JK mosfets. taken the max discharge power from the MPII’s into account, 15kW, I’d set (15/48*938=) 293A rounded up to 300A (assuming no other DC loads/chargers , only the three MPII’s)
So that for starters. Thebn for the first day or two just use the VRM DESS Battery settings to turn balancing ON in the morning a couple of minutes right before the price drop (usually 9, 10 or 11h) and then back OFF again of few minutes before the price shoots up again (usually 16, 17 or 18h) and possibly reduce the total hours not to overcharge from grid when the solar production forcast is high. The best timing is what we will try to automate with the Node-RED flow later. But running it manually for a few days will provide valuable insight how the whole system will respond to the PFCO ‘intervention’ Do not mind what schedule VRM is showing with PFCO switched ON, it will correct back to normal when switched OFF again.
Report back after a couple of days with screenshots of how the system behaved in this Trade mode setup.
PS, the only setting to ‘test’ in these few test days should be the effect of point 12: AC coupled PV feed-in excess. More for me to get to know how that acts than anything else.
Also, do not worry (yet) about small duration overshoots in charging and discharging around the new hour, that can be fine tuned later. What we are looking for is the overall behavior over a full day, in Trade mode, with (for now manual) intervention to charge extra from grid when prices are low. The goal is to target full batteries around or a bit past dinner time, when the grid prices shot up high and the sun goes down.
And you do run VenusOS large beta don’t you? If so:
- Import the standard Node-RED DESS flow from Victron
- Disable that automatically activated inject node that switches on DESS mode 4 (top left) to make absolutely sure it stays on DESS mode 1 : auto (= VRM DESS)
- Copy over all settings described above except the price formulas, make that p*1.21 as this will make the https://venus.local:1881/dess page display pure market prices (including VAT) which makes for much easier interpretation)
- Additionally you may want to change the timer inject node (top right) to inject on the exact hour and then every 3 or 5 minutes, instead on a 3 or 5 minute interval from first injection.
- Finally: do set a reasonable b_goal_SOC of around 85 - 90% at 18:00 or a little later say 19:00 deppending on the amount of solar production at the end of the afternoon.
- Then compare the Node-RED schedules with the VRM-DESS schedules during the day. What you are looking for is how well timed (or not) Node-RED DESS schedules (but not actively driving DESS because that is still done by VRM DESS in mode 1 : auto) to charge your batteries, compared to what VRM DESS is actually doing (helped by the PFCO intervention). Once you get to a point these schedules become pretty predictable to you, we can work on the automation of the PFCO intervention.
And to satisfy my OCD: try to replicate these graphs on the VRM Advanced page (don’t worry about the MP temperature, I mounted the battery temp sensor on the MPII’s toroid transformer to get an impression how it holds these warm days):
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! )
