Load sharing in multi-tenant sites is the controlled distribution of available electrical capacity for EV charging across multiple tenants (companies, residents, or building units) connected to a shared supply. It ensures the total EV charging demand stays within the building’s limits while applying fair allocation rules, metering, and access controls so each tenant receives an appropriate share of charging capacity and costs.
What Is Load Sharing in a Multi-tenant Context?
In a multi-tenant building, multiple users compete for limited electrical headroom. Load sharing coordinates charging across:
– Separate tenant groups (e.g., Company A, Company B, visitors)
– Shared infrastructure (main incomer, transformer, switchboard, feeder)
– Multiple chargers spread across parking levels or zones
Unlike single-owner sites, multi-tenant load sharing must also address fairness, billing separation, and access rights in addition to electrical safety.
Why It Matters for EV Charging Deployments
Multi-tenant sites have unique constraints that make load sharing essential:
– Building capacity is shared with HVAC, lifts, lighting, and other tenant loads
– Electrical upgrades are expensive and require agreement between stakeholders
– Tenants want predictable access, performance, and cost allocation
– Parking layouts often spread chargers across multiple distribution boards
Load sharing enables scalable deployments without oversizing the grid connection and helps avoid disputes about who “uses up” the building’s available power.
How Load Sharing Is Implemented
A typical implementation combines measurement, control, and tenant-specific rules:
– Load measurement at the main supply and/or per distribution board (CT clamps, power meters)
– A controller (local gateway, EMS, or CPMS) that calculates available headroom
– Chargers that accept dynamic current/power setpoints (often via OCPP)
– Tenant logic: grouping chargers by tenant, applying caps, priorities, and time windows
When building load rises, EV charging is reduced across tenants according to the allocation policy; when capacity frees up, charging ramps up again.
Common Allocation Models for Tenants
Multi-tenant load sharing typically follows one or more allocation models:
– Fixed tenant caps: each tenant gets a defined maximum (kW or A) regardless of others
– Proportional sharing: capacity is split by a percentage per tenant (e.g., 50/30/20)
– Guaranteed minimum + shared pool: each tenant has a minimum, leftover capacity is shared dynamically
– Priority rules: critical tenants or fleets receive higher priority during constraints
– Time-based rights: different allocations by time-of-day (office hours vs overnight residential)
These models help balance fairness and utilization while respecting the site power limit.
Billing and Accountability Requirements
Because multiple parties pay for charging, accurate separation is key:
– Tenant-level metering (per charger or per group) for cost allocation
– Support for compliance-grade metering where required (e.g., MID metering)
– Clear mapping of chargers and users to tenant accounts in the backend
– Reporting by tenant: kWh, sessions, peak demand contribution, and costs
Without strong billing separation, load sharing can become a commercial dispute even if the electrical control works correctly.
User Access and Policy Control
Multi-tenant load sharing is typically paired with access management:
– Tenant-specific RFID cards, app users, or fleet accounts
– Tariff rules per tenant (free charging for staff, paid for visitors)
– Reservation and parking policy enforcement where applicable
– Roaming controls (public vs private access)
This ensures power is not only shared electrically, but also aligned with who is allowed to use it.
Practical Design Considerations
Key technical considerations for stable multi-tenant load sharing include:
– Phase-aware load balancing to avoid phase imbalance across different tenant zones
– Fast enough measurement and control to react to building load spikes
– Minimum current thresholds to prevent EVs from pausing when shared too aggressively
– Safe fallback behavior if network communication fails (local control preferred)
– Scalable architecture for adding more chargers without redesigning the entire system
Designing with zoning (by parking level or distribution board) often simplifies both electrical constraints and tenant allocation rules.
Benefits of Load Sharing in Multi-tenant Sites
– Enables more chargers without immediate grid upgrades
– Reduces breaker trips and improves building stability
– Improves fairness and transparency across tenants
– Supports scalable rollout (start small, expand as adoption grows)
– Enables better cost control and predictable tenant charging experience
Limitations and Common Challenges
Multi-tenant load sharing can be challenging when:
– Stakeholders disagree on allocation rules and upgrade responsibilities
– Metering and tenant mapping are incomplete or inaccurate
– Charger placement spans multiple electrical panels with different constraints
– Tenants have different usage patterns (office vs residential) creating perceived unfairness
Clear policies, good metering, and transparent reporting are essential to avoid operational friction.
Related Glossary Terms
Load sharing
Load balancing
Load management
Load measurement
Site power limit
Phase balancing
MID metering
Charge Point Management System (CPMS)
Energy management system (EMS)
Tenant billing allocation