Flicker emission is the level of voltage fluctuation a device introduces into the electrical supply that can cause visible light flicker or other power quality disturbances. In EV charging, flicker emission matters because chargers can behave as dynamic electrical loads, and rapid changes in current draw may contribute to measurable flicker on weak or highly loaded grids. Flicker emission is a key topic in power quality and is often addressed through grid compliance testing and installation design.
What Is Flicker Emission?
Flicker emission is the extent to which a piece of equipment disturbs the grid voltage, causing flickering lights.
– It is linked to rapid voltage changes caused by fluctuating load current
– It is typically evaluated using standardized measurement approaches and limits in EMC and power quality contexts
– It is not the same as harmonic distortion, but both are part of the overall power quality performance
Flicker is most noticeable where the supply is weak, impedance is high, or multiple fluctuating loads operate simultaneously.
Why Flicker Emission Matters in EV Charging
EV chargers are often installed in commercial buildings, residential developments, and public sites where lighting and sensitive equipment share the same electrical infrastructure.
– Excess flicker can lead to user complaints about visible lighting instability
– Poor power quality can trigger stricter grid connection conditions or redesign requirements
– High-density charging sites can amplify effects if multiple chargers ramp power at the same time
– Compliance reduces commissioning risk and improves long-term site stability
For site owners, good flicker performance supports scalable deployment without creating side effects for tenants, customers, or building systems.
How Flicker Emission Happens
Flicker emission is mainly caused by rapid load changes, which create voltage drops across the supply impedance.
– Charger ramps power up or down during session start, stop, or control actions
– Load balancing or power throttling adjusts power in steps or frequently
– Multiple chargers change power simultaneously based on a shared site controller
– A high-impedance grid connection exaggerates voltage variation at the point of connection
Modern chargers are designed to control ramp rates and switching behavior to reduce these effects.
Typical Scenarios Where Flicker Risk Increases
– Rural or remote sites with long feeder lines and higher impedance
– Underground or multi-storey car parks with long cable runs and shared distribution boards
– Sites with many chargers on a limited supply using aggressive dynamic power allocation
– Locations with older lighting systems that are more sensitive to voltage changes
– Installations where chargers share circuits with lighting rather than being properly segregated
How Flicker Emission Is Managed
Flicker emission can be reduced through both product design and site engineering.
– Smooth power ramp-up / ramp-down behavior to avoid abrupt steps
– Proper electrical design with appropriate cable sizing and low-impedance supply routes
– Segregating charger circuits from sensitive lighting circuits where possible
– Coordinated load management strategies that avoid synchronized step changes across many charge points
– Site-level power quality review during planning for high-density deployments
Key Benefits of Low Flicker Emission
– More stable lighting and fewer user complaints at workplaces, retail, and residential sites
– Easier acceptance by facility managers and grid stakeholders
– Improved compatibility with sensitive building loads and automation systems
– Greater confidence when scaling charger counts on a single connection
– Reduced risk of operational restrictions linked to power quality issues
Limitations to Consider
– Flicker performance depends on both the charger and the site’s electrical characteristics
– Weak grid connections may require additional engineering even with compliant hardware
– Aggressive throttling and poorly tuned load balancing can increase perceived flicker risk
– Power quality issues can be multi-factor, involving harmonics, phase imbalance, and voltage dips in addition to flicker
Related Glossary Terms
Power Quality
Voltage Fluctuation
Harmonic Distortion
Load Balancing
Energy Throttling
Active Power Throttling
Three-Phase Power
EV Charger Installation