CPS Energy Peak Capacity Charge Explained

If you live in San Antonio, you’ve probably noticed your CPS Energy bill climbing in the summer — sometimes by $40, $60, or more — even though you haven’t changed your habits. The biggest reason isn’t just running the AC more. It’s a line item most people never look at: the Peak Capacity Charge.

This surcharge adds 2.15¢ per kWh to every kilowatt-hour above 600 during summer. For a household using 1,500 kWh in August — common in San Antonio — that’s an extra $19.35 on top of your normal energy charges.

How CPS Energy’s Rate Structure Works

CPS Energy residential rates have four components. The first three apply year-round; the fourth is the seasonal surcharge:

The all-in rate works out to roughly 13¢/kWh year-round. In summer, once you cross 600 kWh, the marginal rate jumps to about 15.15¢/kWh.

The Surcharge Math at Every Usage Level

The charge only applies to usage above 600 kWh. At 600 kWh exactly, you pay nothing extra. At 601 kWh, you pay 2.15¢ on that single extra kilowatt-hour.

At the San Antonio average of 1,080 kWh, you’re paying ~$10/month in surcharges — about $41 over the four-month summer. At 2,000 kWh, that jumps to $120 for the season.

What an August Bill Actually Looks Like

Here’s the breakdown for 1,200 kWh — a typical August month for a 1,800-sq-ft home with central AC on San Antonio’s north side:

Without the surcharge, that bill would be $165.50. The surcharge is about 7% of the total. In winter, the same 1,200 kWh costs roughly $165 — no surcharge, no higher tier. The rate structure is flat year-round except for this one seasonal add-on.

Why CPS Energy Has This Charge

Summer demand is expensive to serve. When San Antonio hits 100°F+ (15–25 days per year), hundreds of thousands of AC units run simultaneously. CPS Energy keeps peaker plants on standby that only fire up during extreme heat — expensive to maintain year-round for 50–80 days of use.

Peak demand hit 5,900 MW in 2025 vs. roughly 3,000 MW in a typical winter month. CPS Energy has 10,300 MW of total capacity. The surcharge pushes summer peak costs to the customers who drive them, rather than spreading them across every bill equally.

How to Reduce the Surcharge

The only way to fully avoid it is staying at or below 600 kWh in summer. That’s roughly what a well-insulated 900-sq-ft apartment uses. For most San Antonio homes, the goal is to reduce it rather than eliminate it.

1. Set the thermostat to 78°F.

   AC is 60–70% of your summer bill. Every degree below 78°F adds 3–5% to cooling costs. Running at 72°F can add 300–500 kWh/month — all surcharged. Pair 78°F with ceiling fans (15 kWh/month each) for comfort.

2. Pre-cool before afternoon peak.

   Drop to 74–75°F in late morning, then raise to 79–80°F from 2–7 PM. Your home coasts on stored coolness while the AC cycles less during the hottest, least efficient hours.

3. Seal leaks and add insulation.

   CPS Energy offers a free Home Energy Checkup. In older SA homes, leaky ducts waste 20–30% of cooled air. Sealing ducts + R-38 attic insulation can cut 200–400 kWh/month.

4. Run appliances at night.

   Dryers, ovens, and dishwashers generate heat. Running them in the afternoon makes AC work harder. CPS doesn’t have time-of-use pricing, but shifting appliances to evening reduces indoor heat load.

5. Consider solar.

   San Antonio gets 5.3 peak sun hours/day. A 6–8 kW system offsets 800–1,100 kWh/month in summer, potentially dropping you below 600 kWh. CPS offers net metering. Payback: ~8–10 years. See SA solar estimates →

Budget Billing: Smoothing, Not Saving

Budget Billing does not reduce your bill. It averages your annual cost into equal monthly payments — so instead of $90 in March and $230 in August, you pay ~$155 every month. You still pay the same total, including all four months of surcharges.

It’s a cash-flow tool for people who need predictable payments. It removes the shock of an August bill, but it doesn’t reduce usage or your rate. Enroll at 210-353-2222 or through your CPS Energy online account.

How San Antonio Compares to Deregulated Cities

In Houston, Dallas, and Fort Worth, residents shop from dozens of providers. The cheapest fixed-rate plans drop below 9–10¢/kWh with no usage surcharge. CPS Energy’s ~13¢ all-in is in the same ballpark as what most deregulated customers actually pay once you account for people on default or premium plans.

The structural difference: deregulated plans don’t have a Peak Capacity Charge. San Antonio can’t be comparison-shopped because CPS Energy is a monopoly. Live near SA in a deregulated area? New Braunfels, Schertz, and Seguin can shop for plans without a summer surcharge.

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