Underneath every monthly bill is a five-minute auction running across the state of Texas. Here’s how it works, and why it matters even if you never look at a wholesale price chart.
Most of us look at the electric bill, sigh, and pay it. The number on the bottom feels arbitrary — sometimes higher, sometimes lower, often without a clear reason. But there’s actually a fairly orderly process behind that number, and once you understand it, the bill makes a lot more sense.
Every five minutes of every day, ERCOT runs an auction. Generators across Texas — gas plants, wind farms, solar fields, and increasingly, big batteries — submit offers to produce power. ERCOT looks at how much electricity is being used at that moment, how much is available, and where transmission lines are getting crowded. Then a computer figures out the cheapest combination of generators that can keep the lights on, and that combination sets the wholesale price for the next five minutes.
When everything is running smoothly, that price stays in a normal range — somewhere in the ballpark of $20 to $40 per megawatt-hour. When things get tight — a hot afternoon, a cold front, a power plant unexpectedly going offline — the price can jump dramatically, sometimes into the thousands. Those moments are rare, but they’re a major reason your monthly rate is what it is.
The Three Layers of Your Bill
The energy charge. This is the cost of the electricity itself, plus your retail provider’s margin. When you see a plan advertised at, say, 12 cents per kilowatt-hour, this is mostly what they’re talking about.
The delivery charge. This is what your wires company — Oncor in most of East Texas, with CenterPoint, AEP, and TNMP serving other regions — charges to physically move electricity from the power plants to your house. These charges are regulated, identical across all retail providers in your area, and not negotiable. They typically make up a substantial portion of your bill.
Fees, taxes, and small print. This includes ERCOT administrative fees, state and local taxes, and various line items that vary by provider. For most residential customers it’s a small percentage. For businesses with high demand, the demand charges hidden in this layer can rival or exceed the energy charge.
When you negotiate an electric plan, the only thing you’re really negotiating is the energy charge. Delivery is fixed. The rest is mostly determined by who you choose and what fine print you accept.
Why Bills Swing Even on a Fixed Rate
If you’re on a fixed-rate plan, you’d think your bill should be predictable. The kilowatt-hours you use, multiplied by the rate. Simple math. But anyone who’s actually paid attention knows that bills can swing by quite a bit even when the rate hasn’t changed. Two reasons:
The big one is usage. A typical East Texas home can use three or four times as much electricity in August as in April. Air conditioning is the heaviest electrical load in most homes, and a hot summer pushes those numbers higher than people expect. When the bill seems unreasonable, the first thing to check is your actual kilowatt-hours compared to last year’s same month.
The other is plan structure. Some plans have minimum-usage fees that kick in below a certain threshold. Others have tiered rates where the price per kilowatt-hour goes up after you cross a certain level of use. A plan that looks great in summer can look terrible in spring and fall when you’re not using much. The opposite is also true.
What to Do With This Information
Three things every household should make a habit of:
- Look at your bill once a quarter, not just when something looks wrong. Compare your kilowatt-hours to the same month last year. If usage is up, that’s an operational issue — maybe a setting on the thermostat, maybe something in the house running that shouldn’t be.
- Know your contract end date. Most fixed-rate plans roll into a much higher month-to-month rate if you don’t renew. Calendar the end date and start shopping at least a month before.
- Don’t shop on rate alone. Two plans with identical headline rates can produce wildly different bills depending on minimum-usage fees, tiered pricing, and contract length. Read the Electricity Facts Label — it’s a one-page document required for every plan.
For small business owners, the same principles apply, with one extra wrinkle: your bill includes a demand charge based on the highest 15-minute period of usage during the billing period. A single afternoon when every piece of equipment runs at once can drive your demand charges up for the entire month. That’s worth knowing about, and there are ways to manage it.
We’ll come back to demand and how to manage it later in this series. For now, the simple takeaway is that the price you pay for electricity isn’t random — it follows rules, and once you understand them, you can put them to work for you.
— Lee Miller
Lee Miller publishes Texas Forest Country Living and is co-founder of Amerigy Energy, a Texas-based electricity brokerage.