Why solar and EV fleet charging are the ideal pair
Solar generation peaks 10am-3pm. EV van fleet break-charging windows at last-mile depots are 10am-3pm (driver breaks). The alignment is near-perfect. A 500 kW PV system at a depot with 12 EV vans on break-charging absorbs 95%+ of solar output during peak hours. Without EV integration, the same depot might achieve 72-80% self-consumption. The improvement: each percentage point of better self-consumption converts SEG export (8-15p/kWh) into avoided grid import (21-25p/kWh) — worth approximately £5,000-£12,000 annually per percentage point on a 500 kW system.
Charge point specification for solar integration
Charger types for solar-integrated depots: (1) AC Type 2 (7 kW, 22 kW): for overnight charging (7pm-6am, grid-sourced) and off-peak top-up. Lower capital cost (£800-£1,500/socket). (2) DC rapid (50 kW, 100-150 kW): for break-charging windows (30-45 minute charge for 10-40 kWh top-up). Higher capital cost (£12,000-£25,000/unit) but maximises solar absorption during peak generation. Our standard design: 40% DC rapid (break-charging), 60% AC Type 2 (overnight). Smart charge management system prioritises solar generation for break-charging windows, grid for overnight.
Smart charge management systems
Smart charge management is essential for solar + EV integration at scale. The system monitors: solar generation (real-time from monitoring platform), building baseload (HH meter), available solar surplus, EV charge state (per vehicle via OCPP protocol), vehicle departure schedule. Algorithm: allocates solar surplus to EV charging in priority order, topped up by grid when solar insufficient. Leading systems: EO Hub (UK manufacturer), Ohme Business, Indra Business, Open Energy EVSE. We integrate monitoring platform data directly with charge management system — single dashboard for solar + EV operational management.
EV fleet sizing and solar PV design
We design PV and EV charging infrastructure together from the outset. Key inputs: current fleet size and planned 5-year electrification roadmap; vehicle models (eSprinter 111 kWh, Ford E-Transit 68 kWh, VW ID. Buzz 82 kWh, Renault Master E-Tech 87 kWh); daily range requirements and charge depletion; depot shift pattern and charging windows; HH meter data for existing building load. Output: optimal PV system size (typically 100-130% of combined building + EV peak daytime load), charger count and type mix, smart charge management specification, 25-year DCF for combined project.
OZEV Workplace Charging Scheme and EV grant
OZEV Workplace Charging Scheme: £350 per socket, maximum 40 sockets per applicant (£14,000 maximum grant). Zero-VAT on EV charge points (as of April 2022). Combined solar + EV charge capex qualifies for 100% AIA in the year of installation (solar and charge points are both qualifying plant and machinery). OZEV grant application: submit before installation commences.
Common questions
What self-consumption ratio should we model for a last-mile depot with EV charging?
90-97% depending on fleet size and charging pattern. With 12+ EV vans on break-charging at a 500 kW system: 95% typical. Model conservatively at 91-93% to account for seasonal variation and fleet schedule variability.
Can the solar system charge the vans faster than AC charging?
Solar + DC rapid charger combinations can deliver 50-150 kW per charge point during peak solar hours — significantly faster than AC (7-22 kW). For 30-45 minute driver breaks: DC rapid (50 kW) delivers 25-37.5 kWh per session — adequate for 80-120 miles of range.
What happens on cloudy days with EV charging scheduled?
Smart charge management tops up from grid when solar generation is insufficient for scheduled EV charging. Vehicles are always charged for dispatch — solar optimises cost but never compromises fleet availability. OCPP-based systems automatically prioritise by departure schedule.