Last week, the UK reached its highest temperature on record — 40 degrees Celsius, or more than 104 degrees Fahrenheit. On July 20th, as the record-breaking “Red Extreme” heatwave continued to linger, a Bloomberg op-ed reports officials made the decision to pay a record price of £9,724.54 (about $11,685) per megawatt to ensure electricity for South London residents — about 5,000 percent higher than its usual average price of £178 per megawatt hour.

To avoid an energy short squeeze in 2021, the UK paid about £1,600 (more than $1,900) per megawatt to import energy.

But this time, BBC reported, the combination of the heatwave, a storm in Belgium affecting solar power output, and maintenance on overhead all played a part, forcing the National Grid’s Electricity System Operator (ESO) to make the higher-than-usual purchase to avoid blackouts. A spokesperson from the National Grid ESO said a specific circuit was needed to get the energy to the right place.

The power purchased at that rate was only enough to supply about eight households for a year, Bloomberg says, keeping the system stable over the course of an hour, and additional power was purchased at lower rates.

The Bloomberg op-ed argues that power from elsewhere in the country or even turning to offshore wind farms in Scotland should have been a solution. But failures to invest in grid upgrades and resistance to installing more above-ground equipment may have left the system vulnerable. The worry is that next time, even high prices may not be enough, and as an inevitable side effect of a warming planet, residents could face blackouts in the future.