This is a tricky one as it depends so much on how you use your newly converted cooker. If you choose to run the ovens and hotplates 24hrs a day all year round (fully in 'traditional' Aga range cooker mode) then you'll still save money over an oil or gas Aga range cooker also running all the time but its probably only a 10% saving. Not spectacular.
Where things really change though is when you start using the flexibility that 'Electrikit' gives you. For instance it's inconceivable that you'd leave the hotplates on all the time. For background warmth you need only the ovens and with a 10min warm up time you may as well leave the hotplates off till you need them. This alone is an enormous saving even with ovens left on permanently.
But remember the ovens are flexible too! In the summer, when you don't need any background heat in the kitchen, you could turn on when you need them. In the autumn you may wish to run them on low and turn up when you need them. In the winter by all means leave those ovens on so they are always ready for action and drying all those soggy clothes!
All of this combined means very big savings on running a traditional cooker. Every conversion customer gets an in depth guide to getting the most out of their new electric cooker; there is lots you can do!
As for actual, real world costs? We reckon most users will find it costs, at current £ per kwh, between £3-500 a year to run a converted 'Electrikit' system for use with Aga range cookers. On top of this there is no servicing required. This is £5.75-£9.60 per week.
If you have a gas Aga range cooker, depending on if it heats your water, it is probably costing you £20-30 a week to run (much more on LPG) and oil £26-40. I'll leave you to consider the money you could save over the many years one owns a range cooker!
Find out more on our 'Aga range cooker electric conversions homepage'