How ERCOT works

The Electric Reliability Council of Texas keeps supply and demand balanced across the Texas grid second by second, and runs the wholesale market where generators sell the power that retail providers resell to you.

Keeping the grid balanced

Electricity is consumed at the instant it is produced. ERCOT forecasts demand, instructs generators on how much to produce, and manages the transmission network so the balance holds continuously. When the margin between available generation and expected demand narrows, ERCOT issues conservation appeals and, in severe cases, moves through emergency levels that can end in controlled load shedding.

Why the Texas grid stands alone

ERCOT is one of three interconnections in the continental United States and is essentially contained within Texas, with only limited direct-current ties to its neighbours. Historically that kept it outside most federal jurisdiction over interstate transmission, which is the origin of the arrangement.

The trade-off is real. Because those ties are limited, Texas can import comparatively little power when it runs short — which is precisely the situation in which importing would help most.

How the wholesale market prices power

Generators offer power, ERCOT dispatches the cheapest available to meet demand, and the price is set by the most expensive unit required. That price is calculated at locations across the grid every five minutes.

Location matters because of congestion. When transmission capacity between regions is constrained, cheap generation in one place cannot reach demand in another, so the two settle at different prices at the same moment. That is why a windy afternoon in west Texas and a still evening in Houston are, for pricing purposes, different markets.

How that reaches your bill

You do not buy at wholesale prices unless you are on an index product. What wholesale does is set the cost base your retail provider is buying against.

When you sign a fixed contract, the supplier buys forward to cover your expected volume at prices available that day. Your rate reflects that purchase, plus a risk premium for the possibility that your usage differs from the forecast, plus margin. That is why the day you sign matters and why the same account priced two weeks apart can come back materially different.

The generation mix, and why it moves prices

ERCOT runs a large and growing share of wind and solar alongside natural gas, coal and nuclear. Wind and solar have near-zero fuel cost, so when they are producing heavily they push wholesale prices down. When they are not, gas plants set the price and the market follows gas.

In practice this makes Texas wholesale prices more variable than they used to be, with cheap periods that are very cheap and tight periods that are very expensive. For a business, that is an argument for being deliberate about which structure you contract on rather than for having a view about generation policy.

What a business should take from this

• ERCOT is not who you buy from, and no supplier gets preferential treatment from it.
• The timing of when you sign is a real variable, not a formality.
• Location affects price, so intra-Texas comparisons need care.
• Index exposure means direct exposure to a market that can move without limit.
• Outages are a CenterPoint matter; grid emergencies are an ERCOT matter; neither is your retail provider's.