Unstorable, and everything follows from that
Electricity cannot be meaningfully stored at grid scale with current technology — batteries help at the margin and pumped hydro helps a little more, but the overwhelming majority must be generated at the moment it is used.
This single physical fact produces the strangest price behaviour of any commodity. Supply and demand must balance continuously, so the price does whatever is necessary to make that happen, including going negative.
Negative prices are normal now
When wind output is high and demand is low, there is more generation than the system needs. Some generators cannot easily switch off, and subsidy structures can make it rational to keep generating even while paying to offload the output. So the price goes below zero and generators pay consumers to take power.
GB has seen an increasing number of negative price periods as wind capacity has grown. It is not a market failure; it is the market correctly signalling that at that moment, electricity is a liability rather than an asset.
Marginal pricing
In the GB wholesale market, all generators dispatched in a settlement period are paid the price set by the most expensive plant needed — usually a gas turbine. So even in hours when most power comes from wind and nuclear with near-zero marginal cost, the price reflects gas.
This is why electricity bills followed gas prices upwards in 2022 despite a large renewable share, and it is the subject of the ongoing Review of Electricity Market Arrangements, which has considered locational marginal pricing — different prices in different parts of the country reflecting actual grid constraints.
The balancing mechanism
Beyond the wholesale market sits the balancing mechanism, where the system operator buys and sells power in near-real-time to keep frequency at 50Hz. Prices here can spike to extraordinary levels for brief periods when the system is tight. Constraint payments — paying Scottish wind farms to switch off because the grid cannot carry the power south, while paying gas plants in England to switch on — run to hundreds of millions of pounds a year and are a direct consequence of a national price for a physically constrained network.
Retail
For households, Ofgem's price cap limits unit rates and standing charges for default tariffs. Time-of-use tariffs pass wholesale variation through to consumers, and some now offer free or negative-priced periods — effectively retailing the wholesale market's strangest moments.
How you would actually trade it
Wholesale participation requires licensing, credit and balancing responsibility. This is not a retail market.
The practical consumer-side equivalents are meaningful, though: a fixed tariff is a hedge, a time-of-use tariff is exposure to wholesale variability, and export tariffs for solar generation make a household a small participant on the supply side.
Investor exposure comes through generators, utilities and renewable infrastructure funds — the latter typically listed, income-focused, and repriced sharply by interest rate movements.
What goes wrong
- Extreme price spikes and negative prices within the same week.
- Volume risk for generators — a wind farm sells what the wind provides, not what it contracted.
- Regulatory redesign through REMA could change revenue fundamentally for existing assets.
- Curtailment. Grid constraints mean generation that cannot be delivered.
- Cannibalisation. As more wind is built, wind output correlates, and the price achieved during windy periods falls.
This entry describes how a market works. It is not a recommendation, a price forecast, or advice about whether this belongs anywhere near your money. How entries are written.