Hello,
I would like to ask about this issue?
Here is ChatGPT’s statement on this 
What is happening with Victron
Victron in “hybrid” mode (i.e. combination of PV + grid + battery) does not really communicate with an external inverter like a classic on-grid hybrid, but rather behaves like an off-grid system, where:
• The MPPT controller charges the battery based on the voltage on the DC bus,
• The Multiplus/Quattro (AC-DC converter) takes power from this DC bus according to the current need of the load or grid,
• However, there is no direct coordination of power between them, only a common DC voltage as feedback.
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How Victron solves overflows
When the MPPT produces more than the Multiplus can use, the system “solves” it by:
• The MPPT raises the voltage on the DC bus (by about 0.3–0.5 V),
• This “forces” the Multiplus to switch to inverting mode (supplying to AC),
• However, if the Multiplus has nowhere to dissipate power (e.g. full batteries, no consumption, no overflow to the grid),
→ the energy must be lost somewhere.
And the “escape route” is the battery:
its voltage rises slightly, the BMS reacts and starts limiting the current, which causes oscillations between the MPPT and the inverter.
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Why does this lead to large currents on the battery
- Regulation is feedback via voltage, not via direct current control.
→ Every rapid change in power (e.g. a sudden drop in consumption) leads to a transient current through the battery. - Small DC bus capacity (low inductance / capacitance) →
even short-term excess power from the panels “flows” through the battery before the MPPT can reduce the power. - Multiplus does not know what the MPPT is doing — they do not communicate via a fast control protocol, so the response is delayed by hundreds of milliseconds.
Result:
Short spikes in tens to hundreds of amps (depending on the battery capacity and the stiffness of the DC bus).
These spikes will manifest as unnecessary cycling or cell wear.
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Summary
• The description “Victron will raise the DC voltage by 0.5 V to force the inverter to overflow” is absolutely correct.
• The problem with high currents arises because the DC bus and the battery serve as a “buffer” between two non-synchronous sources, without precise coordination of the energy flow.
Yesterday I found out that I probably have two batteries damaged because of this, because they can’t be charged to 100% but stay at about 97%.
I just wanted to ask if anyone has solved this problem, thanks Martin