In the UK, one company gives different buy and sell prices every half hour based on live market rates. [1] You can see that the 'buy back' rate is only about half of the sell rate most of the time.

This is still pretty distorted, because many taxes and distribution fees charged on electricity sold are not refunded on electricity bought back.

[1]: https://www.energy-stats.uk/octopus-agile-outgoing-export-lo...