The price of power
The wholesale price of Christchurch’s electricity, read at the Islington node: ISL2201, the grid exit point in the city’s south-east the power comes through. Not what a household pays; what the market says a megawatt-hour is worth, half an hour at a time.
Couldn’t reach the wholesale price record.
The record as JSON · EMI, the source itself
The week
Half-hour by half-hour, the spike in the early evening is the shape of the country’s demand.
The week’s numbers
The year
The year’s numbers
The same week, a year ago
The comparison’s numbers
The lakes
The water behind the price: hydro storage as a share of the 20-year mean.
The forecast
The forecast’s numbers
The scorecard
Does this change my bill?
Not directly, and for most households not at all. This is the wholesale price, what your power company pays generators for each half-hour at the node. A household bill is the wholesale energy plus everything around it: the national grid, the local lines, your meter, the retailer’s costs, levies and GST.
The energy part is the largest single slice of an average bill, under two-fifths on published industry estimates, but the whole stack sits between this number and what you pay. When wholesale prices spike, a fixed-rate plan absorbs it into the average your retailer already priced in; when they crash, the same plan keeps the change.
Most New Zealand plans charge a fixed cents-per-kWh rate, which smooths this line into a seasonal average rather than passing each half-hour through. A few retailers do sell spot-price plans, on those, this number is your price, and the evening spike is real money. If your bill never names a trading period, you’re on the first kind.
Questions, answered briefly
The wholesale (spot) price at ISL2201, the pricing node at the Islington grid exit point, where Christchurch’s electricity leaves the national grid for the local network. It’s what retailers pay generators, not what a household is charged.
Demand peaks when everyone cooks, heats and showers at once, and the market meets it with whatever generation is left, the most expensive unit dispatched sets the price. Overnight the opposite happens: demand falls, wind and must-run plant stay on, and the wholesale price can drop to zero or below.
Yes, it happens, usually overnight. A generator that can’t cheaply switch off pays the market to stay running rather than stop. It doesn’t mean anyone is paid to use power; it’s the market clearing surplus it can’t store.
EMI, the Electricity Authority’s market information service, shared under CC BY. The public files run a day or two behind the market; a keyed feed reads the real-time price.
The record behind this: prices and forecasts from EMI, the market information service provided by the Electricity Authority (New Zealand), used under CC BY: "EMI: provided by the Electricity Authority (New Zealand)". The spot price is read at ISL2201, Islington. The public files run a day or two behind the market; the real-time feed needs an API key, so what you see here is the latest published period unless the page says otherwise. Forecasts are the pricing manager’s own schedules, the market’s guess, not a promise. The same record is public JSON and this page as markdown is /power.md.