California Commercial Solar and EV Charging: What SDG&E Property Owners Need to Evaluate

EV charging is becoming a standard expectation at commercial properties across California — from office parks and retail centers to warehouses, multifamily buildings, and municipal facilities. For SDG&E commercial property owners already considering solar, the question of whether to integrate EV charging into the project is worth examining carefully. The combination can make financial sense, but it also introduces complexity around system sizing, demand charges, and NEM 3.0 that most installer proposals do not address in full.

Why EV Charging Changes the Solar Sizing Equation

A solar system sized to offset a building's existing electricity consumption will not automatically accommodate EV charging loads. Level 2 commercial chargers draw meaningful power, and a group of chargers operating simultaneously can add substantially to a building's peak demand. If the solar system was not sized with that load in mind, the property owner ends up with a system that covers less of their total consumption than projected — and potentially higher demand charge exposure than before the chargers were installed.

The right approach is to model the EV charging load alongside the building's existing load profile before finalizing system size. That requires actual interval data from your utility bills and a realistic estimate of charging demand based on the number of vehicles, charging patterns, and whether charging is managed or unmanaged. An installer who sizes a solar system without this analysis is working from incomplete information.

SDG&E Demand Charges and the Role of Battery Storage

SDG&E commercial rate schedules include demand charges based on peak 15-minute interval consumption. EV chargers — particularly DC fast chargers — can create sharp demand spikes that drive up the demand charge component of the bill even when total energy consumption is modest. Solar production does not reliably coincide with EV charging demand, especially for properties where vehicles charge in the evening or early morning.

Battery storage can address this by absorbing the demand spike — the battery charges during solar production hours and discharges when EV chargers are active, flattening the demand curve. Whether this configuration pencils out depends on the specific rate schedule, the charging pattern, and the cost of the storage system. It is not a universal answer, but for properties with predictable EV charging loads it is worth modeling explicitly.

NEM 3.0 and Self-Consumption Strategy

Under NEM 3.0, the compensation rate for solar energy exported to the SDG&E grid is significantly lower than under prior policy. This makes self-consumption — using solar production on-site rather than exporting it — the primary driver of project economics. EV charging, when it occurs during solar production hours, is one of the most effective ways to increase self-consumption. A vehicle charging in a parking lot during midday is directly consuming solar energy that would otherwise be exported at a low rate.

This is a genuine advantage for commercial properties with daytime EV charging demand — but it depends on the charging pattern actually aligning with solar production. If most charging happens overnight, the self-consumption benefit disappears. Any financial model that assumes high self-consumption from EV charging should be verified against actual or projected charging schedules.

Questions to Ask Before Committing

Before signing a contract for a combined solar and EV charging project in California, several questions are worth asking independently:

• Is the solar system sized to cover both the existing building load and the projected EV charging load — and is that sizing based on actual interval data?
• Does the financial model account for demand charge impacts from EV chargers, and has battery storage been evaluated as a mitigation strategy?
• Are the projected self-consumption rates based on actual charging schedules, or on optimistic assumptions about daytime charging?
• Which incentives are included in the financial model, and have their current availability and eligibility requirements been verified?

Solar Power San Diego reviews commercial solar and EV charging proposals for California property owners as an independent advisor — with no installer commissions and no financial interest in which project moves forward. We examine the assumptions in proposals, identify where the analysis is incomplete, and give property owners a clear picture of what the project actually involves before they sign.