Real monitoring data from April 7, 2026 — a perfect sunny day in Athens, Greece.
Recorded by Home Assistant + Prometheus. Every data point is real.
The problem: EcoFlow markets the Stream system as "expandable to 6 batteries" with "surplus solar energy automatically transferring between batteries." In reality, a 1200W inverter bottleneck means expansion batteries cannot charge from solar while your home uses power. We paid €849 for an expansion battery that charged from 10% to 19% on a full sun day — while the main battery hit 100% and solar panels were forced to shut down.
EcoFlow's own R&D team confirmed this is a design limitation, not a bug.
Both batteries in the same house, connected to the same solar system. The main battery charges to 99.8%. The expansion battery you paid €849 for? Stuck at 19%. Same sun. Same system.
The gap between yellow (solar) and orange (inverter) is energy your panels produce but the system throws away. The inverter can only push 1200W — everything above is trapped and can't reach the expansion battery.
Green = charge to the main battery. Red = charge to the expansion battery (barely visible). Purple = the inverter busy powering your home. The 1200W inverter spends all its capacity on home load — nothing left for the expansion battery.
Four solar panels producing up to 500W each. When the main battery fills up and the inverter is maxed, the system shuts down the panels. The expansion battery is at 18%, empty and ready — but the bottleneck won't let a single watt through. This is "expandable to 6 batteries" in practice.
What does this mean for 6 batteries? With 6 units, 5 out of 6 batteries get 0W from solar under any normal household load. The "expandable to 23 kWh" marketing claim is functionally meaningless. You're paying for storage capacity the system architecture prevents you from using.