Hello, I am trying to understand my system here, is there anyone with in-depth knowledge on how MPPTs are working together via D.Bus and voltages?
I have two SmartSolar MPPT 100/20 via VE.Direct (left and right picture) and one 150/100 via VE.CAN (center). They seem to use different throttle algorithms, and I want to know if this is a fixed property of the two models or determined dynamically.
The VE.Direct MPPTs seem to use the following algorithm: when effective charge voltage (in dbus com.victronenergy.system/Control/EffectiveChargeVoltage or Link/ChargeVoltage) is reached, throttle down the MPPT (in dbus /DC/0/Current goes down immediately). And they start pumping immediately when battery voltage drops below the effective charge voltage.
In my pictures, the effective charge voltage was 52.6V (due to maximum charge voltage in DVCC set to 52.2V. As far as I understand, effective charge voltage is always the maximum charge voltage plus 0.4V, but never higher than the BMS-supplied CVL + 0.4V. The 0.4V voltage window above the expected charge voltage allows the MPPTs to continue working despite full battery when MultiPlus needs to feed in or cover loads. It can also be adjusted via /Debug/BatteryOperationalLimits/SolarVoltageOffset)
However, the VE.CAN MPPT (in the middle) doesn’t throttle down to zero when reading 52.6V, it plays nicely along. Why exactly is it behaving differently? Because it is “Group master” in the MPPT network or because VE.CAN devices throttle more smartly?
