Why TOU Rates Aren't Enough for EV Charging

Time-of-use (TOU) rates were supposed to solve the EV charging peak problem. Shift load to cheaper hours, flatten the curve, everyone wins. In practice, utilities and researchers are finding something different: TOU rates alone often create secondary peaks — and those new spikes still stress the distribution grid and commercial bills.

That is why utilities are expanding active managed charging: direct, real-time control of when and how hard chargers draw power, instead of relying only on price signals. Baltimore Gas and Electric’s scale-up and recent work from SEPA and EPRI put numbers and language around a shift commercial sites should understand.

Why TOU rates create secondary peaks

TOU rates work by making peak hours expensive and off-peak hours cheap. Drivers and operators respond by scheduling sessions for the cheap window. When thousands of EVs (or dozens of commercial ports) all become eligible to charge at the same “off-peak” start time, a new spike forms at the edge of the cheap period.

Industry analysis has labeled this the snapback peak (or secondary peak). A Utility Dive deep dive summarizing SEPA and EPRI findings put it plainly: time-of-use rates are “creating secondary peaks that cause distribution system congestion,” and “active managed charging” by utilities and third parties “will be needed to unlock EVs’ full potential and decrease distribution system impacts.”

The mechanism is simple:

• Everyone waits for the off-peak window.
• At the window open, many sessions start at once.
• The local transformer, feeder, or commercial service sees a sharp coincident load.
• For a commercial site on a demand charge, that coincidence can set the monthly peak even if the energy was “cheap.”

TOU optimizes energy price. It does not automatically optimize coincident demand. Those are different problems — and EV charging is unusually good at creating the second one. See our guides on what demand charges are and what load management for EV charging actually does.

BGE’s scale-up: from pilot to 30,000 EVs

Baltimore Gas and Electric has become a reference case for moving beyond passive TOU. After a TOU-based pilot, BGE expanded into an active Smart Charge Management program with a third-party aggregator, with plans reported to serve up to 30,000 EV owners by 2027.

The design logic matches the research: rate design alone was not enough to protect the distribution system as EV load grew. Active control — throttling or sequencing charge sessions against grid and program constraints — scales in a way pure price signals do not.

For commercial hosts, the parallel is direct. A dealership, fleet depot, or multifamily property does not need 30,000 vehicles to feel the same physics. A handful of DC fast chargers or a bank of Level 2 ports can set a costly 15-minute peak when they fire together. Active management is the same idea at site scale.

Active managed charging vs. passive TOU

These approaches are often blurred in marketing. The operational difference is clear:

Passive managed charging usually means schedules or TOU-aware timers: charge overnight, avoid 4–9 p.m., and hope coincidence stays low. Active managed charging measures total site (or feeder) demand and adjusts charger power continuously so a threshold is not crossed. Sessions still complete; the power is shaped instead of all drawn at once.

That distinction is why utilities are adding active programs on top of TOU — and why commercial energy management platforms treat demand ceilings as a first-class constraint, not a side effect of a rate schedule. For the seasonal version of this risk, see why summer is peak demand-charge season.

What this means for commercial EV sites

Utility programs are often framed around residential EV owners. The same physics hit commercial sites harder on a per-meter basis:

• Higher power density — DC fast chargers draw 50–150+ kW each; a few concurrent sessions dwarf a typical building baseline.
• Demand charges — Many commercial tariffs bill on the single highest 15-minute interval. One unmanaged spike prices the whole month.
• Ratchets and seasonal rates — Summer peaks and ratchet clauses can lock elevated demand into many following months.
• Rate redesign, not elimination — As we covered in demand charges are being restructured, not removed, subscription and capacity models still penalize peak kW.

Active load management at the site — network-agnostic software that reads building load and shapes charger output — is the commercial equivalent of the programs utilities are scaling for homes. It does not depend on the utility offering a special EV rate. It works against whatever tariff is already on the meter.

What operators should do now

1. Do not treat TOU enrollment as the whole strategy. It helps energy cost. It does not guarantee a low demand charge.
2. Know your demand exposure. Pull interval data or run a planning estimate before adding ports — especially DC fast. Start with our demand charge impact estimator.
3. Design active management in before go-live. Retrofitting after the first shocking bill is more expensive and politically harder inside the organization.
4. Ask whether the control is facility-level. Charger-only schedules are not the same as shaping against total building demand.

EVready’s Energy Guardian platform is built for that layer: rate-aware, network-agnostic control that holds commercial peaks down without cutting charger availability. Pair it with a Playbook assessment so tariff, incentives, and load design are set before hardware is ordered.

Common Questions

Why aren’t time-of-use rates enough for EV charging?

TOU rates shift charging into cheaper hours, but many vehicles and ports become eligible at the same moment when the cheap window opens. That creates secondary (snapback) peaks on the distribution system and at commercial services. Active managed charging limits coincident draw in real time, which price signals alone do not do.

What is active managed charging?

Active managed charging is automated control of charger power based on measured conditions — site demand, grid constraints, or program limits — rather than relying only on a static schedule or TOU price. Chargers stay available; output is shaped so a peak threshold is not exceeded.

How is BGE’s program different from a standard TOU rate?

BGE moved from a passive TOU-oriented pilot to an active Smart Charge Management program that can control charging behavior at scale (reported target on the order of 30,000 EV owners). The active layer addresses distribution impacts that rate design alone did not fully solve.

Does active managed charging help with commercial demand charges?

Yes. Demand charges are billed on peak kW. Active management that holds total facility demand under a ceiling is specifically designed to prevent EV chargers from setting that peak. Sites typically see material reductions in EV-related demand charges without turning drivers away. See Berger Chevrolet and Apple Ford Lincoln for measured examples.

Is load management the same as smart charging?

Smart charging is a broad term for networked chargers that can adjust power or schedule. Load management is the practice of coordinating chargers against a facility (or feeder) limit. All facility-level load management is a form of smart charging; not every smart charger performs true facility-level load management. Details in our load management explainer.

Do I still need active management if my utility has an EV-specific rate?

Often yes. EV rates may reduce or restructure demand charges, but many still include capacity subscriptions, overage penalties, or residual demand components. Active management keeps you inside the cheap band of whatever structure you are on — and protects you if the tariff changes. See how demand charges are being restructured in 2026.