What Is a Demand Charge? (And Do California Residential Customers Pay One?)
Demand charges are why a commercial electric bill can be double what the kWh total suggests. Here's what they are, who pays them, and how to reduce them.
The Simple Definition
A demand charge bills you based on the highest electrical load (kW) you drew during the billing period; typically measured as a rolling 15-minute peak. It's separate from your per-kWh energy charge. You pay both: energy charges for how much total electricity you used, and demand charges for how big your biggest moment was.
Analogy: energy charges are like paying for gallons of water used; demand charges are like paying extra because you opened every faucet in the house at once for 15 minutes.
Who Actually Pays Demand Charges?
- Commercial customers — virtually every commercial rate schedule in California (PG&E, SCE, SDG&E, LADWP, SMUD) includes demand charges, typically $15–$30/kW of monthly peak demand.
- Industrial customers — always, at higher per-kW rates.
- Some residential customers — PG&E, SCE, and SDG&E have piloted or offered residential demand-charge rate plans, but they are opt-in and not the default. Most California residential customers do not pay demand charges directly.
- EV high-power charging — commercial DCFC sites pay demand charges that often exceed the energy charges themselves.
Why Utilities Bill This Way
The grid is sized to handle everyone's peak demand simultaneously. If every business runs AC, pumps, and lighting at 3 PM on a hot day, the utility needs enough capacity to handle that simultaneous load. Demand charges recover the cost of having grid capacity standing by for your biggest moment, regardless of whether you used much total energy.
How Solar and Battery Reduce Demand Charges
- Solar lowers energy charges but often doesn't eliminate demand charges. Your peak demand often happens on cloudy days or at dusk when solar isn't producing.
- Batteries are specifically effective against demand charges. A battery can discharge during your peak-load window, clipping your billing peak even if solar isn't producing.
- Smart energy management (Span panel, Generac Ecobee-style controls) that throttles loads automatically when approaching a demand threshold is an emerging category for commercial customers.
If You Run a Business in California
Battery storage for demand-charge management has some of the strongest commercial ROI of any California energy investment. Paired with SGIP (the Self-Generation Incentive Program) and the federal 30% ITC, the payback period for a commercial battery sized to clip peak demand often runs 4–6 years.
See our Commercial SGIP Battery Storage Guide for details.