What I heard is the reason the 500 comes into play is what I said before about overhead costs and it only gets used 2 percent of the time because coal covers the bulk and it takes a lot to start up and shut down in cost and time so that is not viable in terms of flexible coal power stations shutting down and ramping up regularly. Solar is cheaper but that only works in the day when it can generate and the battery effectiveness is limited. It is only when there is a power supply shortage and prices start to sky rocket that the gas operations start to kick in and take 10 minutes or so so they are far quicker than coal in terms of time flexibility as said in previous posts.
So if one takes total costs over the time it is anticipated to be used thats where the 500 or so comes from in price/cost per usage
Ideally the best way to use/consume electricity is through the day because the battery/storage ability is limited even for use at night and solar is generated in the day where the solar generation uptake is increasing and is the cheapest form of generation.
It might mean, tariffs get re-structured based on smart meters of where there is a lot more now to promote more activity/consumption during the day because the generation/cost of supply is cheaper. So electricity usage through the day becomes cheaper for some than in the night based on comparative generation and supply costs. Remember if you using during the day off your own solar generation at home technically you would not have a need to incur transmission/distribution costs for these time intervals
At the moment you can pay for batteries to store the power domestically but they only last ten years so its debatable how effective they are
