Timeline comparison: Reactive BMS vs Smart EMS v1
Both algorithms share the same goal: reliably charge EVs while managing a battery storage system. The key difference is when and how they decide to charge the battery during idle periods. Reactive BMS uses simple fixed rules. Smart EMS uses price forecasts to plan ahead.
Simple, predictable, no forecasts
Price-aware, optimized, requires forecasts
Before any EV arrives, each system prepares differently...
No planning phase. Uses static parameters:
Analyzes forecasts and creates optimal schedule:
When an EV plugs in, both systems follow the exact same dispatch priority...
Between charging sessions, the systems diverge significantly...
Maintains fixed 80% SOC regardless of price:
If SOC < 80%: Charge from Grid + PV
If SOC > 80%: Hold (no discharge)
No price awareness - may charge during expensive hours
Follows dynamic SOC target from planning:
Cheap hour: Charge to high SOC target
Expensive hour: Allow lower SOC target
Charges when cheap, reserves capacity for peaks
Reliability: EVs always charged
Simplicity: Predictable behavior
Cost: Higher - no optimization
Reliability: EVs always charged
Complexity: Requires forecasts
Cost: Lower - price arbitrage
Key Insight: Identical EV Charging
The EV charging logic (Phase 2) is identical in both algorithms - grid-first priority ensures reliable charging. The difference is in idle period management (Phase 3): Reactive maintains a fixed 80% SOC at any cost, while Smart EMS follows a price-optimized SOC curve that charges during cheap hours and reserves discharge capacity for expensive peaks.
Key Insight: PV Maximization
Smart EMS deliberately lowers SOC before peak PV hours (typically late morning), creating headroom in the battery to absorb solar generation. This minimizes grid export and maximizes self-consumption of free PV energy. Reactive BMS, by always targeting 80% SOC, often has a nearly-full battery when PV peaks - forcing valuable solar energy to be exported at low feed-in rates instead of stored.