I agree that a lot more of the costs should be taken off the per kWh component, though I’d probably put some of it on taxes rather than on the line rental to avoid the change being regressive. Though, some distribution charges do depend on when you use power, so I do want some component to be on the volume you use at peak times.

Having said that, I think you are being overly optimistic on how low wholesale electricity prices will be. I don’t believe that wholesale prices ranging from 2–6p/kWh are enough to ensure sufficient generation. I expect that we’ll see 10% of the time at over 10p, and maybe even 1% of the time above 20p. This doesn’t invalidate your argument, but does need to be taken into account.