Capacity Charges on Commercial Electric Bills: What They Are and How to Reduce Them

Open any Illinois commercial electricity bill and you'll likely find a line item labeled "capacity charge," "PJM capacity," or "capacity cost recovery"—and if your facility has significant demand, that line item may represent 15-25% of your total electricity cost. For many businesses, it's thousands of dollars every month for something that feels abstract and difficult to control.

It's not abstract. And it's not uncontrollable.

Capacity charges are one of the most misunderstood—and most addressable—components of commercial electricity bills in deregulated markets. Understanding exactly what they are, how they're calculated, and which strategies your competitors are already using to minimize them is worth real money: $15,000 to $150,000+ annually for mid-to-large Illinois commercial facilities.

This guide gives you that understanding completely. We'll explain the mechanics behind capacity charges, walk through the exact calculation method that determines your annual cost, describe the proven reduction strategies Illinois businesses are implementing right now, and outline practical next steps you can take to start reducing this line item immediately.

What Are Capacity Charges on a Commercial Electric Bill and Why Are They Costing You So Much?

The Fundamental Problem Capacity Markets Solve

Electricity grids must maintain enough generating capacity to serve peak demand reliably—even if that peak occurs only a few hours per year during extreme weather events. Building and maintaining that backup generation capacity isn't free, and someone has to pay for it.

The regional grid operators—primarily PJM Interconnection for most of Illinois—address this through a capacity market: an auction where generators and demand response resources compete to sell commitments that generation will be available during high-stress periods. The buyers in this auction are utilities and load-serving entities serving commercial and residential customers.

The costs those buyers pay in the capacity auction are then passed through to end-use customers—including Illinois commercial businesses—as capacity charges on electricity bills.

What Are Capacity Charges, Technically?

Capacity charges recover the cost of ensuring adequate electric generation capacity exists to serve peak demand. You are, in effect, paying a reservation fee for the right to draw on the grid during its most stressed moments—whether you actually draw on it then or not.

Key characteristics of capacity charges:

Based on demand, not consumption: Capacity charges are calculated based on your facility's peak demand (kW), not total energy consumption (kWh)
Set annually through PJM auctions: The per-unit cost is determined by PJM's Base Residual Auction approximately 3 years before the applicable delivery year
Difficult to predict: Because auction prices vary significantly year over year, capacity charge costs can change substantially between contract periods
Allocated through the PLC mechanism: Your specific capacity charge is determined by your facility's contribution to PJM's highest-demand hours—your Peak Load Contribution (PLC)

Why Capacity Charges Are So Significant

For Illinois commercial customers, capacity charges typically represent:

10-20% of total electricity costs for offices and retail
15-25% of total electricity costs for manufacturers and industrial users
Up to 30% for facilities with high demand relative to consumption

As a concrete example: a commercial facility with 800 kW of summer peak demand, paying a capacity rate of $9.50/kW/month, pays $7,600/month—or $91,200/year—in capacity charges alone.

The trend is worsening. As detailed in our 2026/2027 PJM capacity auction analysis, the most recent auction cleared at $329.17/MW-day — a 22% increase driven by generator retirements and accelerating data center demand. Illinois commercial buyers with pass-through capacity contracts saw substantial cost increases that many were unprepared for.

How Capacity Charges Are Calculated: The Peak Demand Window That Determines Your Annual Cost

The PLC: Peak Load Contribution

The critical concept that determines your individual capacity charge is your Peak Load Contribution (PLC)—your facility's measured demand during a specific set of high-load hours in the prior year that PJM uses to allocate capacity costs.

In the ComEd service territory (PJM), your PLC is based on your demand during the 5 coincident peak (5CP) hours—the 5 one-hour periods of highest system-wide PJM load in the prior summer (June through September). Your capacity charge for the upcoming year is calculated as:

Your Capacity Cost = PLC (kW) × Capacity Rate ($/kW/month) × 12 months

Where:

PLC is your measured demand during PJM's 5 highest-load hours from the prior summer
Capacity rate is the monthly per-kW rate flowing from PJM's annual BRA auction result

Walking Through the Math

Example: Illinois Manufacturing Facility, 500 kW average demand

PJM's 5 coincident peak hours occurred in late July and early August of the prior summer. Your facility was running at full production during those hours, with a measured demand of:

Hour 1: 485 kW
Hour 2: 510 kW
Hour 3: 498 kW
Hour 4: 502 kW
Hour 5: 475 kW

Average PLC: 494 kW

With a capacity rate of $9.50/kW/month flowing from PJM's BRA:

Monthly capacity charge: 494 kW × $9.50 = $4,693/month Annual capacity charge: $4,693 × 12 = $56,316/year

Now here's the key insight: if that facility had reduced its demand to 300 kW during just those 5 hours—through load shifting, HVAC reduction, or demand response—the calculation would change dramatically:

Revised PLC: 300 kW Revised annual capacity charge: 300 × $9.50 × 12 = $34,200/year Annual savings: $22,116/year

The entire year's savings are determined by what you were doing during approximately 5 hours of the prior summer.

The Timing Challenge

The challenge—and the opportunity—is that PJM's 5 peak hours are not announced in advance. They occur organically when system-wide load peaks, typically on the hottest summer afternoons (usually 2-7 PM on weekdays in July and August). You must either:

Reduce demand proactively on high-probability peak days throughout the summer
Respond to real-time peak alerts from your utility, supplier, or energy advisor
Participate in demand response programs that manage this automatically

Proven Strategies Illinois Businesses Are Using to Dramatically Lower Their Capacity Charges

Strategy 1: Real-Time Peak Alerting and Demand Curtailment

The most direct capacity charge reduction strategy is receiving alerts on days likely to produce PJM's coincident peaks and proactively curtailing demand during afternoon peak windows.

Services exist—including those offered through energy advisors, utilities, and curtailment service providers—that send real-time alerts when grid conditions suggest a potential coincident peak is occurring. Businesses that consistently curtail demand during these approximately 5 summer afternoons can dramatically reduce their PLC.

Real-world result: An Aurora, IL distribution company with 650 kW peak demand enrolled in a real-time peak alerting program. Over two consecutive summers, they reduced their demand by 200 kW during all 5 coincident peak hours through HVAC pre-cooling, pausing non-essential equipment, and rescheduling high-draw processes. Result: $28,000/year in reduced capacity charges.

Strategy 2: PJM Demand Response Participation

As detailed in our demand response programs guide, PJM's Capacity Performance program allows commercial customers to formally commit load curtailment capability in exchange for annual capacity payments.

The elegant synergy: PJM demand response participation simultaneously:

Reduces your PLC (you're curtailing during peak hours)
Generates capacity revenue (you receive payment for committed curtailment)

A facility that commits 400 kW of curtailment capability and earns $60/kW/year in demand response payments receives $24,000/year in revenue while reducing its annual capacity charges by a similar amount—a double savings mechanism.

Strategy 3: Battery Storage for Peak Demand Management

Commercial battery storage systems can automatically discharge during PJM's coincident peak hours, reducing your measured demand without any operational disruption. Well-designed battery systems use predictive algorithms to identify high-probability peak hours and autonomously manage discharge.

For a 500 kW facility with a 250 kW / 500 kWh battery system:

Scenario	Peak Demand	Annual Capacity Cost
Without battery	500 kW	$57,000
With battery (250 kW shaving)	250 kW	$28,500
Annual savings	—	$28,500

Battery storage revenue from demand charge reduction and capacity charge management—combined with demand response revenue—often drives battery payback periods of 3-5 years for Illinois commercial facilities, with the benefits continuing for the system's 10-15 year operational life.

Strategy 4: HVAC Pre-Cooling and Load Scheduling

Pre-cooling is one of the most cost-effective peak demand reduction tactics available to commercial buildings. The strategy:

Pre-cool the building 2-3 hours before the anticipated peak window, drawing HVAC load when system demand is lower
Set HVAC to coast during the 2-4 hour peak window, allowing temperatures to drift within acceptable comfort range
Resume normal operation after the peak window closes

For a 100,000-square-foot office building with 500 kW of HVAC load, effective pre-cooling can reduce building demand by 150-250 kW during peak windows—representing $17,000-$28,500/year in annual capacity charge savings at $9.50/kW/month.

Implementation cost: Reprogramming existing building controls (typically $2,000-$8,000). Payback period: Less than 12 months.

Strategy 5: On-Site Generation During Peak Hours

Facilities with on-site generation—natural gas generators, solar combined with battery storage—can dispatch generation during peak windows, reducing demand drawn from the grid and therefore reducing PLC.

Solar-plus-storage is particularly effective: the battery stores solar production during midday, then discharges during the afternoon peak window (2-6 PM) when PJM peaks are most likely—simultaneously maximizing solar value and minimizing PLC.

Strategy 6: Contract Structure Optimization

If operational demand management isn't feasible for your facility, your contract structure becomes your primary protection:

All-inclusive fixed-rate contracts include capacity charges in the quoted rate—your supplier bears the risk of capacity price escalation. When PJM capacity prices increased sharply for 2025/2026, businesses with all-in fixed rates were completely insulated.

Pass-through capacity contracts expose you directly to PJM auction outcomes. When capacity prices escalate, your costs escalate proportionally. These contracts are generally preferable when capacity prices are declining or expected to decline.

Work with your advisor to model both structures at current capacity pricing levels and forward capacity price expectations before choosing.

Start Reducing Your Commercial Electric Bill Today: Next Steps for Illinois Business Owners

Immediate Actions (This Week)

Identify your capacity charge on your current electric bill—look for "PJM capacity," "capacity cost," or "capacity charge." Calculate it as a percentage of your total bill.
Note your peak demand from recent bills—the highest monthly demand reading in kWh or kW.
Determine your contract structure—call your supplier or check your contract to find out whether capacity is all-in or passed through.

Short-Term Actions (Next 30-60 Days)

Request your interval data from your utility (ComEd or Ameren Illinois). This 15-minute demand data is required for PLC analysis and demand response program qualification.
Consult with a commercial energy advisor who can calculate your current PLC, estimate your capacity charge exposure under current and projected PJM pricing, and identify the highest-impact reduction strategies for your facility.
Evaluate demand response eligibility—if your facility has 50+ kW of controllable load, demand response participation may be immediately available.

Before Your Next Contract Renewal

Capacity charges must factor prominently into your supply contract negotiations. The questions to ask every supplier quoting your business:

"What PJM delivery year capacity price is reflected in this rate?"
"Is capacity included all-in or passed through?"
"If passed through, what is the pass-through calculation method?"
"What happens to my rate if PJM capacity prices increase 30% after I sign?"

Conclusion: Capacity Charges Are Reducible—But Only If You Act Strategically

Capacity charges are not a fixed cost of doing business in Illinois. They are a highly variable expense with multiple levers for reduction—from simple HVAC scheduling adjustments to structured demand response participation to battery storage investment. The businesses achieving the lowest effective electricity costs in Illinois are, almost without exception, actively managing their capacity charge exposure.

The window for reducing your current year's capacity charges through operational changes is the upcoming summer—specifically, the 5 peak afternoon hours that will set your PLC for the following year. Acting before that summer arrives—with a peak alerting service, a pre-cooling strategy, or a demand response enrollment in place—is the only way to influence those charges.

At Commercial Energy Advisors, we provide Illinois commercial customers with complete capacity charge analysis, PLC benchmarking, demand response program access, and contract structure guidance—all at no cost to our clients.

Call 833-264-7776 or request your free capacity charge analysis to find out exactly how much you're paying and what you could realistically reduce.

Frequently Asked Questions

What are capacity charges on a commercial electric bill?

Capacity charges are fees that recover the cost of ensuring adequate generation capacity exists to meet peak electricity demand. In Illinois, they flow from PJM Interconnection's annual capacity auction, where generators bid to have capacity available during high-stress grid periods. Commercial customers pay capacity charges based on their Peak Load Contribution (PLC)—their demand during PJM's highest-load hours.

How are capacity charges calculated for Illinois businesses?

Your capacity charge equals your Peak Load Contribution (PLC)—your average demand during PJM's 5 coincident peak hours from the prior summer—multiplied by the monthly capacity rate from PJM's Base Residual Auction, times 12. Reducing your demand during those 5 specific summer peak hours directly reduces your annual capacity cost.

What percentage of my commercial electric bill are capacity charges?

For most Illinois commercial businesses, capacity charges represent 10-25% of total electricity costs. Facilities with high peak demand relative to consumption (manufacturers, facilities with electric heat) tend to see the highest capacity charge percentages. Reviewing your bill or asking your supplier to itemize charges will reveal your exact percentage.

How can I reduce capacity charges on my commercial electric bill?

The most effective strategies include: reducing demand during PJM's 5 coincident peak hours through HVAC pre-cooling and load scheduling; participating in PJM demand response programs; installing battery storage for peak demand management; and optimizing your supply contract structure (all-in vs. pass-through).

What is a Peak Load Contribution (PLC) and why does it matter?

Your PLC is your facility's measured demand during PJM's 5 highest system-load hours in the prior summer. It's the foundation for calculating your annual capacity charge. A lower PLC means lower capacity charges for the entire following year—which is why managing your demand during those specific 5 hours is so financially valuable.

Are capacity charges the same as demand charges?

No—they're related but different. Demand charges are utility tariff charges based on your highest 15-minute or 30-minute demand in a billing month, applied every month. Capacity charges are based on your coincident peak contribution during PJM's system-wide peak hours, applied annually. Both are demand-based charges, and reducing peak demand generally reduces both, but they're calculated differently.

Will capacity charges keep increasing for Illinois businesses?

Based on PJM market trends, capacity charges are expected to remain elevated through 2027 due to generator retirements, increasing peak demand from electrification, and interconnection backlogs limiting new supply entry. Illinois businesses with proactive capacity management strategies will be better positioned than those relying solely on contract structures.

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