Mixed-Power EV Site Design: L2 + DCFC + MCS
How to lay out a commercial parking site that is 80% Level 2 + 20% DC fast today, but has the conduit and panel headroom for Megawatt Charging System (MCS) Class 8 trucks in 2028 — without trenching the lot a second time.
Why Mixed-Power Beats Single-Modality Sites
A mixed-power site combines Level 2 for long-dwell destination charging, DC fast for short-dwell top-up, and MCS for heavy-duty trucks on one property — sharing transformer capacity, switchgear, payment infrastructure, and load management while preserving each modality's user experience. The design challenge is integrating three radically different electrical and geometric requirements rather than running them in parallel.
EV stall geometry & ADATransformer service upgradesThe 80/18/2 Day-One Mix
For 2026 deployments with a 5-to-10-year horizon, the right day-one mix is roughly 80% Level 2, 18% DCFC, and 2% MCS-ready (conduit and panel only). That anticipates a day-10 mix near 45% L2, 35% DCFC, and 20% MCS — and the infrastructure laid today must reach that endpoint without trenching the lot twice.
EV-ready retrofit vs greenfieldOur Design pillarFuture-Proofing Math: Conduit & Panel Headroom
Future-proofing for MCS adds 6 to 12 percent to day-one electrical capex — an oversized transformer, panel headroom of 30 to 50 percent above day-one demand, and a 6-inch conduit spare per future MCS port. The alternative 2028 retrofit costs $380,000 to $640,000 versus $65,000 to $85,000 today: an 8x to 10x multiple.
NEVI & 30C capital stackDesign my siteWhat does mixed-power EV charging site design mean?
A mixed-power EV charging site combines two or three charging modalities on the same property: Level 2 AC charging for long-dwell destination charging, DC fast charging for short-dwell top-up, and increasingly the Megawatt Charging System (MCS) standard for medium-duty and heavy-duty truck charging. The 'mixed' label captures the design challenge: the three modalities have radically different electrical infrastructure requirements, stall geometries, dwell-time profiles, and pricing models. A well-designed mixed-power site treats them as integrated rather than parallel — sharing transformer capacity, switchgear, payment infrastructure, and load management — while preserving each modality's distinct user experience.
What is the recommended day-one mix of L2 to DCFC to MCS?
For most commercial parking properties planning a 2026 deployment with a 5-to-10-year planning horizon, we recommend a day-one mix of roughly 80% Level 2, 18% DCFC, and 2% MCS-ready (panel and conduit only, no MCS hardware). That mix matches current EV adoption patterns: most charging sessions are still destination Level 2, DCFC demand is growing at 35 to 50 percent annually, and MCS demand is just emerging as Class 8 truck OEMs ramp electric truck production. The day-one mix needs to anticipate the day-5 mix, which we project at roughly 60% Level 2, 30% DCFC, and 10% MCS, and the day-10 mix at roughly 45% Level 2, 35% DCFC, and 20% MCS. The infrastructure deployed today must support the day-10 mix without trenching the lot a second time.
What is MCS and when will it be a commercial reality?
MCS, the Megawatt Charging System, is the SAE-standard high-power charging connector for Class 6 to Class 8 electric trucks. The connector itself was standardized in 2024 (SAE J3271) and supports up to 3.75 MW per port at 1250 volts and 3000 amps, though most first-generation MCS chargers deploy at 1.0 to 1.5 MW. Daimler Truck, Volvo Trucks, Peterbilt, and Tesla Semi have all announced MCS-compatible vehicles for 2026 to 2028 production. Real-world deployments are starting in 2026 at flagship logistics depots in California, Texas, and the Mountain West freight corridor. By 2028 we expect MCS to be a standard line item in any new commercial parking development that wants to serve fleet customers. Designing today for a 2028 MCS retrofit costs $35,000 to $80,000 per future MCS port in upsized conduit and panel capacity; not designing for it costs $180,000 to $400,000 per port retrofitted later.
How much extra does future-proofing for MCS cost on day one?
Future-proofing a new commercial parking development for MCS adds roughly 6 to 12 percent to total electrical capex on day one. The line items are: an oversized utility transformer (typically 2500 to 3000 kVA instead of 1500 to 2000), oversized primary feeder cabling, oversized secondary switchgear, panel headroom of 30 to 50 percent above day-one DCFC demand, and conduit-spare provisions of one 6-inch conduit per future MCS port pulled from the main switchgear to a future MCS pad location. The math: a typical 8-port DCFC site might cost $720,000 in electrical scope; future-proofing the same site to support two MCS ports by 2028 might add $65,000 to $85,000. The 2028 retrofit without future-proofing — trenching the lot, replacing the transformer, pulling new primary feeder — would cost $380,000 to $640,000. The 8x to 10x cost multiple makes day-one future-proofing one of the easiest decisions in the deck.
How should pricing differ between L2, DCFC, and MCS on the same site?
Each modality should be priced separately because each has a different cost-to-serve and user willingness-to-pay profile. Level 2 destination pricing is typically $0.28 to $0.38 per kWh with no idle fee (or a long idle threshold of 90 to 120 minutes), matching the long-dwell destination-charging use case where the driver is at the property for hours. DCFC pricing is $0.42 to $0.62 per kWh with a 10-minute idle threshold and time-of-use modulation through the peak demand window. MCS pricing for fleet customers is typically energy-based at $0.32 to $0.44 per kWh under contract pricing or $0.48 to $0.58 per kWh for retail, with no idle fee but with reservation-required access. The same payment infrastructure can support all three pricing models; the rate tables and idle-fee policies are configured per-port at commissioning.