The Challenge
A facility's 250 kVA generator auto-started during any grid disturbance. Grid voltage sags (brief, <1 second) often triggered automatic startup. The generator would run for 5–15 minutes even for sags that resolved within seconds.
What Became Visible
Load analysis revealed that 60–70% of generator starts were for transient grid disturbances lasting <5 seconds. The generator would run 10–15 minutes at low load (5–10% capacity) before automatic shutdown. This low-load operation was highly inefficient and contributed to maintenance issues. Generator was being started 6–8 times daily for sags, each incurring 8–10 minute fuel burn.
What Changed
25 kWh lithium battery system installed with hybrid power controller. Battery responds to transient sags automatically. Generator only starts for sustained outages lasting >30 seconds.
How it worked: Battery provided instantaneous power during voltage sags, bridging the gap until grid stabilized. For sustained outages >30 seconds, generator auto-started with battery still supplying current to smooth load ramp. Generator never ran at low load; it came online already supporting 30–40% capacity from battery discharge.
Results
transient events handled by battery
reduced low-load operation
from reduced start/warm-up cycles
fuel + generator wear reduction
Battery storage is most effective when paired with generators — it eliminates low-load, inefficient generator operation during transient events and startup phases.
Operational Reality
Facilities with transient-heavy grids (frequent voltage sags) can reduce generator runtime 30–50% with battery storage, eliminating inefficient low-load operation.