On-site generation is the production of electricity at or near the point of use—such as a building, depot, or charging hub—using technologies like solar PV, wind, combined heat and power (CHP), or other distributed energy resources. In EV charging, on-site generation reduces energy costs, lowers carbon intensity, and supports grid-constrained sites by supplying part of the charging demand locally.
Why on-site generation matters for EV charging
Charging sites can become large electricity consumers. On-site generation can:
– Reduce grid electricity purchases and improve operating cost predictability
– Lower Scope 2 emissions for fleets and property owners (depending on accounting)
– Support net-zero charging strategies when paired with reporting and certificates
– Reduce peak grid import when combined with load management and storage
– Improve resilience when paired with batteries and islanding-capable systems (where allowed)
Common on-site generation technologies
– Solar PV (rooftop or carport): most common for workplaces, depots, and parking areas
– Small-scale wind (site-specific and less common in urban settings)
– CHP (often gas-based; may reduce costs but not necessarily emissions)
– Biogas/biomass generation (context-dependent, regulatory dependent)
– Fuel cells (niche; depends on hydrogen supply and economics)
How on-site generation integrates with charging
On-site generation is typically coordinated through an energy management layer:
– Direct self-consumption: chargers use locally generated energy in real time
– Export/import balancing: excess PV exports to the grid; deficits are imported
– Managed charging shifts EV load to match solar production (“solar-following”)
– On-site battery buffering stores excess generation for later charging peaks
– Site controllers enforce limits such as maximum site demand or export caps
Benefits
– Lower lifetime energy costs where generation is cost-effective
– Reduced grid congestion impact and improved site sustainability profile
– Better charging economics for predictable daytime dwell (workplaces, logistics)
– Enhanced ROI when paired with storage and demand charge mitigation
– Supports corporate and municipal climate commitments
Limitations and considerations
– Generation is variable (PV depends on daylight and season), requiring smart controls
– Upfront capex and structural considerations (roof capacity, carport construction)
– Interconnection rules may limit export or require protection upgrades
– Oversizing without storage can lead to high export and limited self-consumption
– Carbon claims must be clearly defined (market-based vs location-based accounting)
– Maintenance and monitoring are needed to ensure performance over time
Typical EV charging site types using on-site generation
– Office buildings and business parks (daytime charging aligns with PV output)
– Fleet depots (PV + storage + managed charging for cost and peak control)
– Retail and destination sites (carport PV as both shade and power source)
– Municipal facilities (schools, depots, parking lots) supporting public goals
Related glossary terms
Renewable integration
On-site energy storage
On-site battery buffering
Microgrid
Microgrid controller
Managed charging
Load management
Peak shaving
Net-zero charging
Green power purchase agreement (PPA)