It is exactly why the market is the best approach for electricity. Everyone is incentivized to produce electricity as cheap as they can. Otherwise it doesn’t pay off to produce cheaper because one gets punished by having to sell for less anyway.

Can you give an example of a better method?

The one that I can think of is the government sets the amount of electricity produced, and then it’s rationed. But I doubt the UK would be happy with rationed electricity where your power shuts off the second it’s over. That would be essentially mandatory blackouts all the time.

Not to mention the cost would be held by the government, so you end up paying it in taxes anyway.