Though green energy is cheaper to generate, on the market it's sold at the same, higher price of gas and other fossil fuels. That's down to the way the market's set up. It's similar to how houses are sold based on the price of neighbouring homes, rather than what it costs to build.
It's mainly set up this way because the grid always has to be balanced: the UK's energy needs (or 'demand') matched perfectly with an equal amount of power supply. The grid calls on all different types of power, from gas to renewables, to help with its crucial balancing job.
It wouldn't be entirely fair to pay some energy generators less for their power when they're fulfilling the same important function. This means that the highest price ends up setting the market price. When gas prices are high, all electricity prices are too.
We’re pushing for a system in which more and more of the electrons are green ones – because the more green power in the grid, the less we need to rely on expensive, dirty gas imports to meet our energy needs at all.