We got one about a year ago, didnt notice much difference, but had solar switched on at the same time, so that could have cancelled out any increase, i really dont know. not that our solar has produced much till this summer anyway. From talking to friends and family, it depends how you use it. When we had one installed at work our bills halved, simply because at that time operation hours were 5am till 2.30pm so for the most part work was done during off peak and shoulder periods, and only half hour in the peak time. Now we have staff there till 6pm they have gone up, as well as increases. But most people say if you do as much as you can in off peak and shoulder times, you can actually make a huge saving. I try to cook all meals and get the washing etc done in the morning during shoulder time, then just re-heat dinner when its peak time, so im using more power in the cheaper times. i wait till late at night to turn the dishwasher on and save as much washing etc as i can for weekends when its shoulder all day.