In The Law of Averages I took a look at how pretty much everywhere in the world is reported at some time or another to be heating faster than the average (which is a clever trick). This time I want to take a look at how averages play out when it comes to wholesale pricing of UK electricity.

In the context of electricity, I first encountered how the use of averages can be misleading in relation to heat pumps. I wrote about it in A Heated Debate. In essence, my point was that it’s common to find it being said that heat pumps are 3-4 more times efficient than gas boilers (with a gas boiler co-efficient of performance – or COP – of around 0.9 compared to a heat pump’s average COP, often said to be 3-4). The problem with the reference to the average is that it distracts from the reality that heat pumps are most efficient in the shoulder seasons of spring and autumn and least efficient in winter when the need is greatest. Given that in the UK electricity prices tend to be around 4 times higher than gas boilers, a heat pump COP 4 times higher than the COP of a gas boiler might make it a marginal decision as to which is the better choice for any particular individual (leaving aside the usually significantly higher costs of installation). However, the fact that demand for energy is highest when the heat pump’s COP is lowest, clearly shifts the economic case away from heat pumps and gas boilers. The Wiessman website makes this perfectly clear:

Your heat pump may not work as efficiently when the outdoor temperature falls to below -5 ℃. When the temperature outside is around 7 ℃, the average heat pump should have a CoP of around 4.5, however this figure can drop to 2.3 when the temperature outside decreases to -7 ℃. This shows how much the cold weather can affect the efficiency of the appliance.

In other words, while average numbers can have their uses, they can also be extremely misleading when it comes to seeing the bigger picture.

From time to time I take a look at excellent websites such as iamkate to keep an eye on average electricity prices in the UK, as well as to see how the UK’s electricity is being generated. Even in summer, electricity generation is all over the place. Sometimes (in the middle of the day, in summer, if it’s sunny and windy) renewables can be generating a significant proportion of our electricity, with gas generation and reliance on imports via the interconnectors sinking to virtually nothing. On rare occasions, I even notice the UK being a net exporter of electricity. Usually, however, we are a significant net importer (as I write, on a windy evening – with wind generating 24.1% – we are still importing a net 4.3%, and gas is generating 46.9%. The following – even windier – morning sees the UK still relying on gas for 28.7% of its electricity and on imports for a net 9.7%). Sometimes we are heavily reliant on gas, sometimes we aren’t. It has to ramp up and down inversely to the way the vagaries of renewables ramp up and down. It occurs to me that managing the national grid must be an extremely challenging and onerous task.

That, however, is a digression. The main curiosity I have noticed is with regard to wholesale electricity prices, which regularly seem to be higher than £100 per MWh, but which are often lower than that and on rare occasions are even negative. This results in an average price which bears no relation to the highs and lows, other than being what it says it is – an average: much lower than the highs and much higher than the lows and the occasionally negative prices.

We all know that UK electricity prices are amongst the highest in the industrialised world. Renewables enthusiasts argue that renewables are cheap and that allowing gas to set the price is the problem. I struggle with that for lots of reasons. First, I have seen the price being negative, even when gas is still being used to generate electricity. Secondly, although correlation is not causation, as Jit has demonstrated globally it is the case that the more renewables there are on a system, the higher are the prices. Thirdly, as I have shown the claim that renewables are cheap stands up only if you add significant made-up carbon costs onto gas and if you ignore the whole-system costs that are specifically and solely attributable to renewables.

How does all this play out in the context of average prices? Purely by chance, as I write, iamkate tells me that the current price of electricity in the UK is £122.94 per MWh; over the past day it has averaged £109.28 per MWh; over the past week it has averaged £84.25 per MWh; over the last year it has averaged £81.41 per MWh; and over “all time” (which seems to be since the website started monitoring the price in 2012) it has averaged £69.30 per MWh. At face value those figures might suggest a concerning upward trend (as we add more renewables to the system). And concerns in that regard might not be misplaced. However, it’s the impact of averages that I want to explore.

Happily, there is a website that allows us to interrogate the prices on a half-hourly basis. We can also use it to explore the figures in many other different ways. Strangely, perhaps, this tells us that the third lowest average weekly price so far this year was week 1, when the average price was £73.90 per MWh (the lowest and second lowest were weeks 8 and 9 – late February, going into early March – at £71,59 and £72.12 respectively). Weeks 19-22 inclusive, however (weeks when renewables – solar, certainly – should be doing well) all saw average weekly prices over £100 per MWh. The last week for which figures are available (week 25) shows an average price of £104.44 per MWh.

It’s also possible to explore price trends by day, and even to explore the half-hourly prices. Taking the last week as an example, we see the following (prices are highest, lowest, and average, per MWh):

11^th June 2026: £128.99; £90.56; £107.74.

12^th June 2026: £112.69; £26.13; £77.76.

13^th June 2026: £102.46; £-29.99; £26.00.

14^th June 2026: £123.16; £40.21; £79.80.

15^th June 2026: £140.00; £86.09; £106.50.

16^th June 2026: £141.01; £86.03; £108.77.

17^th June 2026: £141.00; £73.61; £104.79.

With the partial exception of 13^th June, I find those numbers to be alarming. When domestic demand should be low (during a week close to the summer solstice) and when “cheap” renewables (espcially solar) should be performing extremely well, prices are relentlessly high.

But it gets worse, and this is the problem with averages. If we look at each of those dates in turn, we find that the times of greatest domestic demand (breakfast time and evenings) are also the times of highest prices, and the times of lowest domestic and possibly lowest overall demand are often the times that see the lowest prices. Taking those same seven days, I set out below the times when the highest and lowest prices were set:

11^th June 2026: 7-7.30pm; 3.30-4pm.

12^th June 2026: 7.30-8am; 3-3.30pm.

13^th June 2026: 9-9.30pm; 12.30-2pm.

14^th June 2026: 10-10.30pm; 3.30-4am.

15^th June 2026: 8-8.30pm; 4-4.30am.

16^th June 2026: 7.30-8.30pm; 1-1.30pm.

17^th June 2026: 8.30-9pm; 2.30-3pm.

Defenders of the system might argue that I am simply stating the obvious – it’s a basic law of economics that as demand increases so does the price, and as demand falls, again, so does the price. However, markets usually respond to increasing demand by increasing supply, with the result that the market (and hence the price) returns to equilibrium.

This is not the case with the UK electricity generating market, where renewables enjoy favoured status on the Grid, and guaranteed (generally) high long-term prices under Contracts for Difference. Worse still, renewable energy cannot respond to increasing demand. It supplies what it supplies, and that’s that (unless the generators are paid to constrain supply because they’re generating more than the Grid can cope with). Solar, especially, is a massive failure in terms of meeting our requirements at times of peak demand. Both over the year as a whole and in respect of peaks of daily demand, solar is hopeless, and can only be of much use (beyond small-scale domestic) if and when large-scale and cheap battery storage is in place. It provides very little electricity in winter, and it provides little or nothing (depending on the time of year) at the times of daily peaks – breakfast time and in the evening.

Thus, at the very times when the law of supply and demand puts pressure on prices, the UK electricity generation system is unable to respond, other than by asking gas to ramp up and by taking electricity from the European mainland via the interconnectors. This inevitably has the result of raising prices at times of peak demand by more than would be the case in a “normal” market.

Just as EV mandates seem designed to cause maximum harm to UK car manufacturers, the way the UK electricity generation system operates seems designed to maximise costs to the consumer. And the problem with relying on average figures is that they obscure the worst aspects of the system. They hide the fact that the time when we use most electricity is the very time when we pay the highest prices for it. Claims of low prices, on the rare occasions when renewables are working hard for us, are meaningless if those times coincide – as they often seem to do – with low demand. It’s the worst of all possible worlds, and reliance on average prices handily obscures that fact for those who have sent us down this road and who want us to accelerate the journey.