Why Texas Commercial Electricity Gets Expensive in Summer (Structurally, Not Mysteriously)

Say a Houston warehouse runs 42,000 kWh/month. Example numbers to show the math, not a live quote. On a 9¢/kWh fixed supply contract, that usage costs roughly $3,780 in energy charges. On a variable index contract that spikes to 18¢/kWh during a July heat wave, the same usage costs $7,560 for that single month, before demand charges are even added. That's a $3,780 swing on one month's bill, and it isn't random. It's how the ERCOT market is built to behave every summer.

ERCOT runs the Texas grid as an energy-only market. There's no separate capacity payment guaranteeing generators get paid whether or not they're needed. Instead, prices rise when reserves get tight, and reserves get tight almost exclusively in summer, when every business and household in the state is running air conditioning at the same time. That statewide AC load drives ERCOT's peak demand each year.

When reserve margins shrink during a summer afternoon, ERCOT's pricing mechanisms allow wholesale prices to climb sharply, sometimes for just an hour or two, sometimes for a stretch of days during a heat event. That's scarcity pricing. It isn't a glitch and it isn't mysterious. It's the market doing exactly what an energy-only design is supposed to do: pay generators more to keep running when the system needs them most. The problem is that any contract structure tied to real-time or day-ahead wholesale prices feels that spike directly.

An index contract prices your energy off the ERCOT wholesale market on a rolling basis, sometimes hourly, sometimes monthly. In the shoulder seasons, that structure often looks attractive because wholesale prices sit low when demand is mild. Summer flips that entirely. The same index that saved you money in April can double or triple your energy line item in August, and there's no ceiling written into most index agreements.

Fixed-rate contracts don't eliminate ERCOT's summer volatility, they just move the risk onto your supplier for the length of the term. That's the entire value of a fixed contract for a business with predictable, HVAC-driven load: an office, a retail store, a restaurant kitchen running the same equipment day in and day out. We recommend fixed contracts for the vast majority of commercial accounts under about 100,000 kWh/month specifically because summer scarcity pricing is a known, recurring feature of ERCOT, not a rare event worth gambling on.

For larger accounts with interval data recorder (IDR) meters, ERCOT layers on another summer mechanic entirely: the four coincident peaks, or 4CP. ERCOT identifies the four 15-minute intervals, one in each of June, July, August, and September, when statewide demand hits its highest point. Your account's usage during those exact intervals determines your share of transmission cost allocation for the following year. Miss those intervals with high demand and you're locked into a higher transmission cost bucket for twelve months, regardless of what you do the rest of the year.

• 4CP only applies to interval-metered (IDR) accounts, typically larger commercial and industrial operations, not standard small business meters.
• The four peak intervals are never announced in advance. ERCOT identifies them after the fact based on actual grid-wide demand.
• Reducing load during predictable high-risk afternoon windows in June through September lowers your 4CP exposure even without knowing the exact peak hour.
• 4CP cost allocation shows up on your bill the following year as part of transmission and distribution charges, not as a separate summer line item.
• A broker or energy manager tracking your interval data can flag high-usage patterns worth addressing before peak season, not after the invoice arrives.

Separate from the energy rate itself, most commercial bills carry a demand charge based on the single highest 15-minute kW interval of the billing cycle. For example, say demand charges make up 30 to 40 percent of the monthly bill for an energy-intensive account on CenterPoint's grid. Summer is when demand charges spike hardest, because HVAC systems pull their maximum draw on the hottest afternoons, exactly when everyone else's AC is doing the same thing across the grid.

• Your contract renews or expires between May and September without a locked renewal already in place.
• You're on a variable or index-priced supply agreement with no rate cap.
• You don't know whether your account is interval-metered (IDR) or a standard meter, which determines whether 4CP applies to you.
• You've never had a broker review your demand profile to see how much of your bill is energy versus demand charges.
• You operate in a deregulated TDU territory (Oncor, CenterPoint, AEP Texas, or TNMP) but haven't compared your rate against the current competitive market in over a year.

None of this requires predicting what ERCOT prices will do this summer, and we won't pretend to know that. What's predictable is the structure itself: statewide AC load drives scarcity pricing, scarcity pricing punishes index and holdover contracts, and 4CP quietly resets transmission costs for larger accounts every year. A business that understands the mechanics can negotiate around them. A business that doesn't finds out the hard way on an August invoice.