Britain Sometimes Has Too Much Electricity. So Why Are Bills Still So High?
At certain times, Britain has more electricity than the system can comfortably use. Wind farms may be paid to reduce output - a practice called curtailment. Wholesale prices can fall towards zero, or below it. Yet the average business does not receive an invitation to run the factory for free.
That's not evidence that somebody has forgotten how electricity bills work. It's evidence that electricity has to be delivered in the right place, at precisely the right time - and the wholesale price is only ever one part of what ends up on an invoice.
Electricity is not one national bucket
The wholesale market prices electricity nationally, but the physical network that actually delivers it has real, physical limits. Generation can be plentiful in one part of the country and constrained from reaching demand in another, simply because the wires connecting them can only carry so much.
Why generation gets curtailed
When there's more renewable generation available than the network can move to where it's needed, or than the system can safely absorb, something has to give. Wind farms get instructed to reduce output - curtailment - and the cost of doing that, plus whatever's needed to keep the system balanced second by second, is a real and growing cost. It has run into the billions of pounds annually in recent years, recovered ultimately through network and balancing charges rather than showing up as a headline on the wholesale price.
Why a negative wholesale price doesn't mean a negative bill
Even on a day when the wholesale price genuinely goes negative, a business's bill is built from far more than the wholesale rate: network charges, balancing costs, policy costs, taxes, losses, and whatever hedging or contract structure the supplier has in place. A striking wholesale number on a sunny, windy Sunday doesn't cancel out the rest of the bill - it's one input among several, and usually not the largest one on a fixed contract.
Where flexible businesses may benefit
Sites with genuine operational flexibility - shifting pumping or refrigeration loads, controlling EV charging, charging a battery, using thermal storage, or running a process with real timing flexibility - are the ones actually positioned to benefit when the system has a surplus. The opportunity isn't in the headline wholesale number; it's in being able to move demand towards the moments when the system genuinely wants more of it.
Why location matters
An identical battery, an identical flexible load, can have meaningfully different value on two different sites, because the local network, the connection, the export limits and the flexibility opportunities available at each site are different. "The market went negative" is a national statement. Whether a specific site can actually capture that value is a local one.
The emerging market for increasing demand
System operators are increasingly exploring ways to reward sites for genuinely increasing demand at constrained times and locations, rather than only paying generators to reduce output. It's an evolving area, not yet a mature, universally available product - but the direction is a real one worth watching.
Sources and further reading
Britain doesn't simply need more electricity. Increasingly, it needs generation and demand to line up in the right places at the right times - which is a more complicated problem, but also a more interesting commercial one for any site with genuine flexibility. If that sounds like your site, get in touch.