What Is a Capacity Charge and How Does It Affect Your Energy Bill?

A capacity charge is a fee added to your commercial electric bill that pays for the power plants the grid keeps on standby for its highest-demand hours. It has nothing to do with the commodity rate you locked in, and for many businesses, it's one of the largest line items on the bill. 

If you’re buying energy in a deregulated market, understanding capacity costs is essential to controlling risk and building accurate budgets. Here’s what you need to know.

What Are Capacity Charges?

Capacity costs are fees you pay to ensure the electric grid has enough power plants available to meet demand, especially on the hottest or coldest days of the year.

Capacity charges are often one of the largest line items on a commercial bill. Unlike your energy rate, they’re driven by how the grid plans for your future demand, not just what you use today.

Grid operators like PJM Interconnection (PJM), Independent System Operator-New England (ISO-NE) and New York Independent System Operator (NYISO) run capacity auctions where power plants get paid to stay ready. The total cost of that readiness is then passed through to customers based on their contribution to the system’s peak demand.

In simple terms, if your business uses more energy during the grid’s peak hour, you pay more capacity costs.

What's the Difference Between a Capacity Cost and a Capacity Tag?

Capacity auctions determine the price for each area being served. Prior to each auction, grid operators will provide estimates for each region's peak electricity usage. The auction exists to ensure that there is enough capacity to accommodate the estimated peak usage. 

The capacity charges on your bill are made up of two parts, the capacity cost and the capacity tag. But what is a capacity cost vs. a capacity tag? 

The capacity cost is the price set per kilowatt hour (kWh) by the grid operator. The capacity tag, also called your peak load contribution (PLC), is the total kWh used by your building on the peak hours of the peak days. 

Capacity tags are determined on an annual basis. At the end of each summer, the regional transmission organization (RTO) is required to identify the highest peak load hours that occurred during a specific period. The utility then measures each customer's usage during those hours to calculate that customer's peak load contribution.

Why Do Capacity Charges Matter for Your Business?

Capacity isn't a small line item. It's often one of the top three drivers of cost for commercial buyers.

Capacity auctions, which occur a few times a year, determine capacity prices one to three years before the delivery year. That means decisions happening today affect what you’ll pay far into the future, even if the market looks calm right now.

For example, the July 2025 PJM capacity auction cleared 22% higher than the previous year, meaning many businesses will see significant increases on their bills in the 2026/2027 delivery year.

How Can You Reduce Your Capacity Charge?

Because your capacity charge is set by your usage during a handful of peak grid hours each year, cutting usage in those specific hours lowers what you pay for the entire following year.

Three common strategies businesses use to reduce their capacity charges are:

• Peak shaving: reducing load during forecasted peak hours by curtailing non-essential equipment or drawing from on-site storage.

• Load shifting: moving flexible operations, like charging, pumping, or batch processing, to off-peak hours.

• Timing around the coincident peak: using grid peak forecasts to know which hours actually drive your capacity tag, so you act only when it counts.

Implementing one, or all, of these strategies can help reduce your capacity charges overall. Peak hours, however, are only confirmed after the fact, so a reliable forecast is just as important in reducing capacity charges.

How Should You Manage Your Capacity Charges?

Ignoring capacity leads to surprises. Managing it well leads to savings and stability.

Effective capacity management starts with knowing your building's coincident peak hours before they happen, not after the utility bill arrives. Facilities that track grid peak forecasts can adjust operations in the hours that actually set next year's capacity tag, rather than reacting to a bill they can't change. Pairing that forecast with an ongoing energy management strategy turns capacity from a once-a-year surprise into a cost that's monitored and planned for like any other capital expense.

Key Takeaway

A capacity charge is what a business pays for the grid to keep enough power plants ready for its highest-demand hours, calculated from the capacity cost (the per-kWh price) multiplied by the capacity tag (how much energy the building used during the year's peak hours). Because the capacity tag is set once a year based on those peak hours, tracking peak forecasts and shifting load away from them is the most direct way to lower next year's charge.